DEPARTMENT OF MEDICAL RADIOGRAPHY AND RADIOLOGICAL
A THESIS SUBMITTED T
RADIOLOGICAL SCIENCES, FACULTY OF HEALTH
UNIVERSITY OF NIGERIA ENUGU CAMPUS
1
NWOBI, CHIGOZIE IVORPG/M.Sc/03/37246
SONOGRAPHIC ASSESSMENT OF FOETAL THORACIC CIRCUMFERENCE AS A PREDICTOR OF GESTATIONAL
AGE IN MAIDUGURI, NORTH EAST NIGERIA
DEPARTMENT OF MEDICAL RADIOGRAPHY AND RADIOLOGICAL SCIENCES, UNIVERSITY OF NIGERIA, NSUKKA
A THESIS SUBMITTED TO THE DEPARTMENT OF MEDICAL RADIOGRAPHY AND
RADIOLOGICAL SCIENCES, FACULTY OF HEALTH SCIENCES AND TECHNOLOGY
UNIVERSITY OF NIGERIA ENUGU CAMPUS
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SONOGRAPHIC ASSESSMENT OF FOETAL THORACIC CIRCUMFERENCE AS A PREDICTOR OF GESTATIONAL
AGE IN MAIDUGURI, NORTH EAST NIGERIA
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SONOGRAPHIC ASSESSMENT OF FOETAL THORACIC CIRCUMFERENCE AS A PREDICTOR OF GESTATIONAL
AGE IN MAIDUGURI, NORTH EAST NIGERIA
BY
NWOBI, CHIGOZIE IVOR PG/M.Sc/03/37246
DEPARTMENT OF MEDICAL RADIOGRAPHY AND RADIOLOGICAL SCIENCES
FACULTY OF HEALTH SCIENCES AND TECHNOLOGY COLLEGE MEDICINE
UNIVERSITY OF NIGERIA ENUGU CAMPUS
FEBRUARY, 2012.
3
TITLE PAGE
SONOGRAPHIC ASSESSMENT OF FOETAL THORACIC CIRCUMFERENCE AS A PREDICTOR OF GESTATIONAL
AGE IN MAIDUGURI, NORTH EAST NIGERIA
BY
Nwobi, Chigozie Ivor PG/M.Sc/03/37246
A Dissertation Submitted to the Department of Medical Radiography and Radiological Sciences, Faculty of Health Sciences and Technology, College Medicine, University of Nigeria, Enugu Campus
IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF MASTER OF SCIENCE (M.Sc) DEGREE IN
MEDICAL IMAGING
SPECIALTY: MEDICAL IMAGING
SUPERVISOR: PROF. K. K. AGWU
FEBRUARY, 2012.
4
APPROVAL PAGE
Name: NWOBI, CHIGOZIE IVOR
Reg. No. PG/M.Sc/03/37246
Degree: M.Sc
Specialty: Medical Imaging (Medical Ultrasound)
Title of Dissertation: Sonographic Assessment of Foetal Thoracic
Circumference as a Predictor of Gestational
Age in Maidurguri, North East, Nigeria
Examination Committee
…………………. ………………………. Dr. C. U. Eze Prof. K. K. Agwu Head of Department Supervisor
……….…………….. Dr. T. T. Marchie External Examiner
Date of Approval …………..
5
DEDICATION
To my parents; Chief J. U. Nwobi and Late Augustina Nwobi of blessed
memory. My Aunty, Miss Margaret Nweze, for their love and support.
6
ACKNOWLEDGEMENT
I am grateful to Almighty God for his love and guidance for granting me
grace to successfully complete this study. The success of this study was
made possible by many people who were involved in supervision,
support, provision of material resources, advice and encouragement. My
gratitude goes to my supervisor, Prof. K. K. Agwu for his constructive
criticism, motivation and support. I appreciate Dr. Ahidjo Ahmed
(Former Head, Radiology Department, University of Maiduguri Teaching
Hospital UMTH, Consultant Radiologist) and Prof. Audu Bala (former
Deputy CMAC, UMTH and consultant Obstetrics and Gyaenacologist)
for their permission and provision of subjects for data collection and for
also sharing their experiences and expertise in the study. The staff of
radiology and O&G departments are appreciated for their collaboration
and provision of enabling environment for the study.
Special thanks to Prof. Tahir A., Chief Medical Director, University of
Maiduguri Teaching Hospital, for his encouragement and support to
seeing the completion of this work.
Dr. Eze C.U., Head of department of Medical Radiography and
Radiological Sciences, Dr. Okeji Mark, Dr. Ogbu S.O.I, Mr. Ochie Kalu,
Mr. Nwadike and Mrs. Angel Mary provided advice and contributions to
the dissertation, for which I am grateful.
7
I acknowledge Mrs. Idigo F.U. and Dr. Okaro, former heads of
department, for the guidance and assistance in making the work possible.
Finally, I want to acknowledge, My late elder brother,Simon Nwobi, my
brothers and sisters, colleagues, friends and relations for their moral
support and love during the period of the study.
8
ABSTRACT
The purpose of this research was to establish a nomogram of thoracic
circumference as a predictor of GA. The foetus of 907 singleton pregnant
woman referred to the Radiology Department of UMTH and obtained through
consecutive enlistment were scanned for the purpose of establishing a
nomogram of thoracic circumference (TC) as a predictor of gestation age. Only
apparently healthy subjects were enlisted and those between gestational age of
15 weeks-41 weeks were included. A cross sectional prospective research
design was adopted for this study using a convenient sampling technique.
Ethical approval was also obtained from the ethical committee of the hospital
and informed consent was obtained from each participant before data collection
commenced. The sonographic examinations were performed using a two-
dimensional, high resolution, real time ultrasound, ALOKA Prosound 3500
manufactured in Japan in 2005, and equipped with a 3.5MHz curvilinear,
transabdominal transducer. The TC was measured and in accordance with the
recommendations of American College of Radiology (ACR). Regression
analysis was applied to establish the relationship between TC and GA and the
coefficient by Pearson’s moment correlation. The BPD, HC, AC and FL were
also measured and the accuracy of TC in predicting GA compared with these
biometric parameters. Geometric mean was used to determine fetal growth rate.
Student t test (two tails) was used to determine if there was statistical
difference between TC of Caucasian and that of Nigerian population. The TC
values ranged from 9.159cm to 32.168cm for the 15-41 weeks of gestation. The
growth rate at the second trimester was 0.8169/week and third trimester
0.8217/week. The coefficient of the relationship between TC and GA was
0.974 and the regression analysis yielded the equation y = 4.65 + 1.13TC. The
accuracy of TC in predicting GA is 97.40% while those of BPD, HC, AC
and FL accuracy were 98.24%, 98.06%, 97.12%, and 98.62% respectively.
There was no statistically significant difference between TC and other
established biometric parameters in predicting GA. The accuracy of TC to
predict GA was highest at the second trimester.
9
TABLE OF CONTENTS
Title Page i
Approval Page ii
Dedication iii
Acknowledgement iv
Abstract vi
Table of Contents vii
List of Tables x
List of Figures xi
List of Appendices xiii
List of Abbreviations xiv
CHAPTER ONE: INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the Problems 4
1.3 Objectives of the Study 5
1.4 Significance of the Study 6
1.5 Scope of the Study 6
1.6 Limitations of the Study 7
1.7 Literature Review 7
1.8 Operational Definition of Terms 11
10
CHAPTER TWO: THEORETICAL BACKGROUND
2.1 Embryology of Foetal Chest Development 15
2.2 Anatomy 17
2.3 Hereditary Defect of Foetal Chest 18
2.4 Sonographic Assessment of Thoracic Circumference as
Prediction of Gestation Age 21
2.5 Sonographic Assessment of other Parameters to Determine
Gestation Age 24
2.6 Other Imaging Modalities used for Fetal Dating 32
2.7 Clinical Methods of Estimating Gestational Age 33
CHAPTER THREE: RESEARCH METHODS
3.1 Introduction 36
3.2 Research Design 36
3.3 Setting of Study 36
3.4 Study Population 37
3.5 Determination of Sample Size and Sampling Technique 38
36 Sources of Data 38
37 Ethical Consideration 39
3.8 Recruitment of Subject, Inclusion/Exclusion Criteria 39
3.9 Method of Data Collection 40
3.10 Dating Model 47
11
3.11 Method of Data Analysis 48
CHAPTER FOUR: PRESENTATION OF RESULTS AND
DISCUSSION
4.1 Introduction 49
4.2 Results 49
4.3 Inferential Analysis 56
4.4 Feta Thoracic Circumference Growth Rate 56
4.5 Prediction of GA from TC 56
4.6 Discussion 63
CHAPTER FIVE: SUMMARY AND CONCLUSIONS,
5.0 Summary of Major Findings 66
5.1 Conclusions 67
5.2 Recommendations Based on Finding 67
5.3 Study’s Contributions to Knowledge 68
5.4 Areas of Further Studies 68
References 69
Appendices 75
12
LIST OF TABLES
Table 1: Age Variability in Weeks 32
Table 2: Distribution of the participants according to tribe 50
Table 3: Mean values of TC matched against GA 53
Table 4: Comparism between 50th percentile TC in Nigerians
(derived nomogram) and the caucasians 55
Table 5: Predic5ted GA from equation 75th Percentile in Nigerians
GA = 4.65 + 1.13 TC 57
Table 6: Regression model for TC against BPD, FL, HC. 62
Table 7: Gestational age groups and their coefficient of determination 62
Table 8: Mean values of BPD, FL, HC and TC with GA 78
Table 9: Comparison of mean values of TC and HC against GA 79
13
LIST OF FIGURES
Fig 1: IUGR Pictural diagram 14
Fig 2: Foetal chest sonogram 17
Fig 3: Foetal ribs and spines sonogram 17
Fig 4: Four Chamber sonogram with colour Doppler 22
Fig 5: Four heart chamber view and chest circumference of foetus 22
Fig 6: Foetal skull with Biparietal diameter 25
Fig 7: Foetal Derived Head Circumference Sonogram 27
Fig 8: Correct Femur Length outline Sonogram 30
Fig. 9a: Incorrect the femur (f) length sonogram should not be measured
unless it is perpendicular to the transducer 30
Fig.9b: Incorrect bowed femur length sonogram 31
Fig 10:Sonographic appearance of derived thoracic circumference 41
Fig 11: Imaging of the Four Heart Chamber View 43
Fig 12: Illustration of the levels the four heart chamber 44
Fig 13: Illustration of the two perpendicular diameter used to drive
the Thoracic Circumference 45
Fig 14: Sonographic appearance of thoracic circumference with the
four chamber view of the foetal heart 45
Fig 15: Age distribution of the participants 51
Fig 16: Gestational age distribution of the foetus 52
Fig 17: Scatter diagram of mean TC against weeks of gestation 54
14
Fig 18: Scatter diagram of TC against BPD 58
Fig 19: Scatter diagram of TC against HC 59
Fig 20: Scatter diagram of TC against AC 60
Fig 21: Scatter diagram of TC against FL 61
Fig. 22: Sonogram of foetal thoracic circumference 80
15
LIST OF APPENDICES
Appendix i: Ethical clearance UMTH 73
Appendix ii: Participant consent form 74
Appendix iii: Table 8: mean values of BPD, FL, HC and TC
With GA. 76
Appendix iv: Table 9: comparison of mean values of TC and HC
against GA 78
Appendix v: Fig 22. Sonogram of foetal thoracic circumference
source manjucakesh 79
Appendix vi: Data capture sheet 80
Appendix vii: Raw date sheet 82
16
LIST OF ABBREVIATIONS
AA - Aorta
AC - Abdominal Circumference
ACR - American College of Radiology
AGA - Average Gestational Age
ASD - Atrial Septal Defect
BPD - Biparietal Diameter
CRL - Crown Rump Length
DA - Dutus Arteriosus
D1 - One Diameter
FE - Foetal Ear
FCC - Foetal Chest Circumference
FHS - Foetal Heart Structure
FL - Femur Length
GA - Gestational Age
HC - Head Circumference
HL - Humeral Length
IUGR - Intra Uterine Growth Restriction
LA - Left Atrial
LMP - Last Menstrual Period
MPA - Main Pulmonary Artery
MHz - Megahertz
17
OOD - Outer Orbital Diameter
RA - Right Atrial
TC - Thoracic Circumference
UMTH - University of Maiduguri Teaching Hospital
VSD - Ventricular Septal defect
YSD - York sac Diameter
18
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
The introduction of sonography by Donald and colleagues in 1958 is now
regarded as one of the major milestones of modern medicine (Johnson,
2005). For the first time it became possible to obtain information about
the foetus and its environment directly with a non-invasive diagnostic
procedure considered safe even when used repeatedly. In Nigeria there is
unprecedented growth in the application of ultrasound in general and in
obstetrics in particular due to its diagnostic/evaluation yield to physicians
and fetal gender determination (Johnson, 2005; Eze et al., 2010).
Ultrasound is useful in terms of accurate assessment of gestational age,
detection of abnormalities, evaluation of foetal growth and well being,
and guiding obstetricians and gynaecologist with in-utero diagnosis and
treatment (Johnson, 2005).
Diagnostic ultrasound plays key role in providing solution to obstetric
problems. In the developed world such as Japan and Great Britain,
ultrasound is also a screening test and the “routine-scan” is seen as part of
obstetrics care, capable of providing important information for improving
pregnancy management (Johnson, 2005). Accurate knowledge of
gestational age is prerequisite for best obstetric care, including evaluation
19
of fetal growth and management of preterm and post term pregnancies as
stated by Pekka and Vilho 2001 and Ola-oja,2005 . Every 30 seconds a
baby dies of preterm birth (Berghella, 2010). Over 1 million babies die in
the world every year due to problems related to being born too soon
(Requejo and Meriald, 2010). Failure to obtain accurate gestational age
can result to poor maternal and foetal outcomes (Konje et al, 2002) .
The estimation of GA is one the commonest indications for obstetrics
ultrasound investigation (Eze et al. 2010).Currently, real time scanners
which produce dynamic images of the moving fetus can be depicted on a
monitor screen. Very high frequency sound waves of between 3.5 to 7
megahertz (MHz) are generally used for this purpose. Repetitive arrays of
ultrasound beams scan the foetus in thin slices and are displayed on the
monitor screen. Movements such as foetal heartbeat and malformations in
the foetus can be assessed and measurements can be made accurately on
the images displayed on the screen. Such measurements form the corner
stone in the assessment of gestational age, size and growth in the foetus
(Johnson, 2005).
However, before the advent of ultrasound, assessment of foetal age was
purely by clinical evaluation and dependent on last menstrual period
(LMP) given by the patient and/or physical examination of the fundal
height of the pregnant women and Delee’s or quickening test. These
20
methods sometimes are inaccurate and unreliable due to the various
reasons (Agwu et al., 2008, Mongelli and Gardosi,2008). These includes
presence of Uterine leiomyoma coexisting with pregnancy resulting in
wrong fundal height measurement particularly when the date of the LMP
is not accurately known, as it is generally the case (Campbell et al.,
1985;Apfel and Green, 1999; Chuldleigh and Thilaganathan,2004; Agwu
et al. 2008). However, even when certain LMP is known it has been
shown that ultrasound is more accurate (predictive error 7.4-7.7 day) than
LMP (10 day) between estimated day of delivery and actual day of
delivery at 11-16weeks of gestation. Ultrasound is superior to LMP by at
least 1.7 day according to Pekka et al, 2001; Agwu et al,2008 ; Mongelli
and Gardosi, 2008)
With the introduction of ultrasound over five decades ago, the
assessment of foetal age has been improved, through the use of these
parameters; Yolk Sac Diameter (YSD), Crown Rump Length (CRL),
Biperiatal Diameter (BPD), Femur length(FL), Abdominal
Circumference (AC), Head Circumference (HC) are currently in use,
others are Humeral Length (HL),Outer Orbital Diameter(OOD), Foetal
Heart Structure (FHS), Foetal Ear (FE), whose accuracies are dependent
on trimesters and ease of obtaining measurement depending on the foetal
position (Pekka & Vilho, 2001;Ola-oja,2005). Foetal thoracic
21
circumference is rarely used as a predictor of gestational age and/or foetal
abnormalities in Nigeria, this may be due to lack of knowledge of fetal
thoracic measurements and also absence of standardised technique to
obtain such. Available foetal thoracic measurements for the estimating of
gestational age are one derived from Caucasian and United State of
America(USA) mix population which may be different from local place
understudy due to racial differences in FL as shown in other studies (De
La Verga,2008; Moongelli and Gardosi, 2008).Further limitation of the
previous study were; poor resolution of ultrasound machine used with
attendant challenges in foetal thoracometry, scanty description of
technique and small sample size.TC has advantage of easy of
measurement because it is not dependent on foetal lie, presentation, and
anatomical shape/size of foetal body as it affect other parameters such as
BPD,HC and FL.
This study was aimed to establish a nomogram by producing prospective
second and third trimesters foetal thoracic circumference dating
parameter and growth chart using modern real-time ultrasound equipment
in a Nigerian population.
1.2 Statement of the Problems
1. The accuracy of most biometric parameters in predicting
gestational age (GA) varies as pregnancy progresses, thus there is a
22
continuous search for other parameters in for a multiple
assessment in order to improve accuracy of GA
prediction(Ogunsina et. al, 2001).
2. The relationship between thoracic circumference and gestational
age in Nigeria foetus have not been investigated.
3. Present nomogram of thoracic circumference used in predicting
GA is based on Caucasian studies which may be inaccurate due to
possible racial difference, thus the need to derive a nomogram for
the Nigerian location.
4. The accuracy of the thoracic circumference in predicting GA has
not been compared with other biometric parameters like BPD, HC,
AC, FL in Nigeria population.
1.3 Objectives of the Study
The general objective of the study was to assess foetal thoracic
circumference as a predictor of gestational age.
Specific Objective
1. To measure the foetal thoracic circumference from 15weeks to 41
weeks with GA
2. To determine relationship between thoracic circumference and
gestational age.
23
3. To develop nomogram of the TC for the population under study
and compare the finding with Caucasian values
4. To determine foetal growth rate
5. To establish relationships and accuracies of prediction of GA
between TC and BPD, FL, HC
1.4 Significance of Study
1. The result of this study will be of immense help to the
sonographers, radiologists and obstetrician and gynecologists in
multiparameter prediction of GA. By providing a nomogram for
better estimation of gestational age for local populations studied
2. The result will be used as a predictor of gestational age of a fetal
thoracic sparing Intrauterine growth restriction (IUGR).
3. A standardized foetal thoracic circumference measurements
technique which will enable another biometric parameter for
gestation age estimation to be introduced.
1.5 Scope of the Study
The subjects were drawn from Nigerian populations and apparently
normal pregnant women whose obstetrics scan were done in Radiology
department, University of Maiduguri Teaching Hospital. The inclusion
criteria were all singleton foetuses with no abnormality visualized and
pregnant Nigerian women with no prolonged illness from their mid-
24
trimester (15-41weeks) at UMTH, northeast of Nigeria. The study
covered a period 39 months between August 2007 to October 2010.
1.6 Limitation of the Study
1. The study was cross-sectional and did not involve follow up of
cases.
2. The ultrasound equipment was not regularly re-calibrated after
break down, for accuracy of measurement. However, the machine
has installed software for quality assurance and re-calibrate
programmes and performs it regularly
3. A detail menstrual history was not taken, most women were not
certain of their Last menstrual period due to very high illiteracy
level and religious bias
4. The women were not scanned for sole purpose of dating
5. Composite dating model (BPD+FL+HC) was used instead of LMP
or Ovulation date or Conception date (Mclennan and schluter,
2008).
1.7 Literature Review
The estimation of gestational age (GA) is one of the commonest
indications for obstetrics ultrasound investigation (Rumark, et al., 2005).
In obstetrics ultrasonography, accurate prediction of GA is essential for
the proper management of the patient.
25
The most accurate way to calculate the gestational age is by knowing the
date of conception. However, most patients are unaware of the date of
conception. The earliest clinical measurement of GA is based on the
mother’s last menstrual period LMP (Apel and Green, 1999; Konjel et al.
2002). The first day of the last menstrual period (LMP) is used to
calculate the expected date of delivery (EDD). The LMP is unreliable (de
la Verga, 2002; Chuldleigh and Thilaganathan, 2004) due to the
following circumstances:
• When the date of the LMP is not accurately known especially
among illiterate women.
• When the menstrual cycle is not 28days long
• When the menstrual cycle is irregular
• When the patient has bled in early pregnancy.
Furthermore, about 40% of all pregnancies are not sure of their LMP (de
la Verga, 1999; Konjel et al. 2002), thus the need to have an accurate GA
of the foetal cannot be overemphasized. Studies comparing
ultrasonography estimation of the GA during the first trimester and
prediction of GA by means of LMP have shown sonography to be more
accurate than the later (Krishnendu, 1998, Pekka, 2001; de la Verga,
2002).
26
Ultrasound is a readily available, non-invasive and safe means of
evaluating foetal health, determination of gestational age, and assessing
the intrauterine environment. Several ultrasound parameters have been
used to estimate gestational age. The most commonly used parameters
are: in first trimester are Gestational sac diameter (GSD), Crown Rump
Length (CRL), while second and third triemester are the Biparietal
Diameter (BPD), Femur Length (FL), Head circumference (HC), and
Abdominal Circumference (AC), others are Humeral Length (HL), Outer
Orbital Diameter (OOD), Fetal Heart Structure, Fetal Ear, Fetal Thoracic
Circumference (TC), Fetal Thoracic Length (TL), Fetal Cerebelum (FC),
and Inner Orbital Diameter (IOD), Fetal Kidney Length (Davidson et
al,1981; Mayden et al., 1982; Mercer 1987; De la Verga ,2000; Nahid
et al, 2007; Yusuf et al., 2007; Mongelli and Gardosi 2008).
Measurement of a wide variety of parameters have been devised to
establish gestational age. The CRL GA estimation is between + 5 to ± 7
days accurate and the GSD is accurate in GA estimation by ±17 days
(Kurtz et al, 1999). However, as pregnancy advances to the second and
third trimester, the accuracy of estimating the GA by CRL and GSD
reduces (Krishnendu, 1998) thus the use of other biometric parameters
like AC, HC, BPD, FL and TC.
27
Ultrsononic assessment of gestational age by Horace Thompson in
Denver was the first to described in 1965 the measurement of the thoracic
circumference as a method for studying foetal growth. The measurement
had an accuracy of within 3cm in 90% of the patient (Woo, 2001). It was
reintroduces by Manfred Hangman in Bonn. TC was correlated with birth
weight of the foetus later when gray scale obstetric scans was developed
(Woo, 2001). Gamett and robinson in Sydney reported on measurement
of the foetal trunk area as a means to access foetal size in 1975. However,
the above lacked well defined landmark for consistency in measurement.
In 1976, the Hansmann group described further landmark for the
measurement of the thoracic circumference as a similar plane as that used
for the abdominal circumference. Circumference measurements of the
foetal trunk is considered superior to diameter measurements of the
former is less affected by the change in shape of the foetal body (Woo,
2001) . Fetal thoracic circumference as predictor of GA a new nomogram
was established by Chitkara et al ( 1987) in subject population of 570
normal women between 16 and 40 weeks gestation. A linear growth
pattern of thoracic parameters throughout gestation was noted.
In 100 normal pregnancy 13 to 41 weeks’ gestation foetal chest
circumference (FCC) versus gestational age and femur length were
constructed and a nomogram establish with FCC. Fetal chest
28
circumference measurement was useful in the antenatal prediction of
lettal or clinical severity pulmonary hypoplesia (Fong et al., 1988).
However, ultrasound machine used at that time cannot match the current
state- of- art ultrasound machines (2005) with higher resolution to assess
the foetal TC.
1.8 Operational Definition of Terms
Assisted Reproductive Technologies (ART) terminology (Zegers-
Hoschschid et al, 2006)
Clinical pregnancy: Evidence of conception from time of fertilization to
the end of the embryonic state 8 weeks after fertilization (Zegers-
Hoschschid et al, 2006)
Embryo: Product of conception from time of fertilization to the end of
the embryonic state 8 weeks after fertilization (Zegers-Hoschschid et al,
2006)
Gestational age: Age of an embryo or foetus calculated by adding
14days (2weeks) to the number of completed weeks since fertilization
(Zegers-Hoschschid et al, 2006).
29
Fertilization: The penetration of the ovum by the spermatozoa and
fusion of genetic materials resulting in the development of a zygote
(Zegers-Hoschschid et al, 2006)
Foetus: The product of conception starting from completion of
embryonic development (at 8 completed weeks after fertilization) until
birth or abortion (Zegers-Hoschschid et al, 2006)
Full term: A birth that takes place at 37 or more completed weeks of
gestational age. This includes both live births and stillbirths (Zegers-
Hoschschid et al, 2006)
Gestational sac: A fluid-filled structure containing an embryo that
develops early in pregnancy usually within the uterus (Zegers-Hoschschid
et al, 2006).
Pulmonary hypoplasia: is incomplete development of the lungs,
resulting in an abnormally low number or size of bronchopulmonary
segments or alveoli (Sanders &Winter, 2004)
Delee’s test: The first time the fetal heart can be heard with the foetal
stethoscope, usually at about 16 week’s gestation (Sanders &Winter,
2004).
Quickenine baby move 16 to 18 weeks (Sanders & Winter, 2004).
30
Quickening: The time when the mother first feels the baby move 16 to
18 weeks (Sanders & Winter, 2004).
Composite (average) gestational age: The mean of more than one
parameter used in estimating gestational age (BPD +HC+FL/3)
(Subbarao et al, 2003).
Intrauterine growth restriction: Previously known as intrauterine
growth retardation or IUGR, is a weight for a specific age below the 10th
percentile
31
Fig 1: IUGR Pictural diagram,
Source AIUM: American Institute of Ultrasound in Medicine, 2006),
ACR: The American College of Radiology, ACOG: The American
College of Obstetricians and Gynecologists.
32
CHAPTER TWO
THEORITICAL BACKGROUND
2.0 Embryology of Foetal Chest Development and Anatomy
2.1 Foetal Thoracic Wall
Vertebral column: the vertebral column is derived from the scleretomes
of somites. Each scleretome is divided into three parts; cranial, middle
and caudal. A vertebra is formed by the fussion of the caudal part of one
scleretome and the cranial part of the next sclerotome. It is therefore,
intersegmental in position (Singh and Pal, 2001).
Ribs: the ribs are derived from the sclerotomic mesenchyme that forms
the vertebral arches. These extensions are present not only in the thoracic
region but also in the cervical, lumbar and sacral regions. They lie ventral
to the mesenchymal basis of the transverse processes with which they are
continuous. In the thoracic region, the entire extension (called the
primitive costal arch) undergoes chondrification to form the ribs (Singh
and Pal, 2001).
Sternum: the sternum is formed by the fusion of two sternal bars or
plates that develop on either side of the midline. The fusion of the two
sternal bars first occurs at the cranial end (Manubrium) and proceeds
caudally. The Manubrium and the body of the sternum are ossified
33
separately. The Xiphoid process ossifies only late in life (Singh and Pal ,
2001).
The diaphragm: the diaphragm is a partition that separates the thoracic
and abdominal cavities. The pericardial and pleural are above it, whereas
the peritoneal cavity is caudal to it. The development of the diaphragm is
therefore, intimately related to the development of these cavities. (Singh
and Pal, 2001).
According to Moore and Persaud (2003), the diaphragm develops from
four structures; Septum transversum, Pleuroperitoneal membranes, Dorsal
mesentery of oesophagus, Muscular in growth from lateral body walls.
The transversum is established in the 4th week. The diaphragm descends
to the thoracic level in the 6th week and parts of it reach the lumbar region
by the 3rd month.
The heart: the development according to Singh and Pal (2001) is, the
heart develops from the splanchnopleuric mesoderm related to that part of
the intra-embryonic coelom that forms the pericardial cavity. This
mesoderm is the cardiogenic area.
The heart is the most susceptible to teratogens between 3 and 6 weeks. It
can be affected up to 8th weeks. Clusters of blood and vessels forming
cells (angioblastic islands) appear in the 3rd week. At the end of this week
34
(18th day) the cardiogenic area, heart tubes and pericardium have formed.
At the end of the 22nd day, the head fold is established: the heart and
pericardium now lie ventral to the foregut. At this stage, the heart tube
shows its main subdivisions. The heart begins to beat in the 4th week.
Septa in the heart form between the end of the 4th week and the beginning
of the 7th week. The spiral septum is formed in the 5th week. Aortic arches
are established during the 4th to 5th weeks. Veins also begin to be formed
at the same time (Moore and Persaud, 2003).
2.2 Anatomy
According to Moore and Dalley (1999), the thorax (chest) is the superior
part of the trunk between the neck and the abdomen. It is formed by the
12 pairs of ribs, sternum (breast bone) costal cartilages and 12 thoracic
vertebrae. These bony and cartilaginous structures form the thoracic cage
(rib cage) which surrounds the thoracic cavity and supports the pectoral
(shoulder) girdle.
35
2.3.0 Hereditary Defect of Fetal Chest
2.3.1 Dextrocardia
The heart lies on the right side of the thorax instead of the left. It is
caused because the heart loops to the left instead of the right. It may
coincide with situs inversus, a complete reversal of asymmetry in all
organs.
2.3.2 Atrial Septal Defect (ASD)
In this acyanotic heart defect, an opening between the right and left atria
allow blood to flow from the left to the right, resulting in ineffective
pumping of the heart, thus increasing the risk of heart failure.
There are 3 types
Fig. 2: Foetal chest Sonogram courtesy of Dr. Prem Chand, Pakistan
Fig. 3: foetal ribs and spine sonogram courtesy of Dr. PK Srivastava,India, and Dr. Ravi
36
a. The most superior portion is the sinus venosus portion of the
septum. Defect in this portion are associated with partial
anomalous pulmonary venous return
b. The midportion (area of the fossa ovalis) of the septum is the
secundum portion. This is the most common area for the defect to
occur. Because the foraman ovale is patent in fetal life, it is
difficult to diagnose a defect in this portion prenatally
c. The most inferior portion is the osteum premium portion. A defect
in this portion is associated with atrioventricular septal defect.
2.3.3 Ventricular septal defect(VSD)
In a VSD, the most common acyanotic heart disorder an opening in the
septum between the ventricles allow blood to shunt between the left and
right ventricles. This results in ineffective pumping of the heart and
increases the risk of heart failure.
Morphologically, the ventricular septum is divided into 2 segments: the
membranous which is the small thin portion inferior to the aortic root and
the muscular portion is divided into 3 portions:
a. The inlet portion which is at the level of the atrioventricular valves
b. The outlet or infundibular portion which is the anterior portion at
the level of the semilunar valves
37
c. Muscular septum which extends from the membranous portion of
the apex
There can be more than one ventricular septal defect in the same or
different portions of the septum. They are often associated with other
types of congenital heart disease.
A combination of four cardiac defects: ventricular septal defect, right
ventricular outflow tract obstruction (pulmonary stenosis), right
ventricular hypertrophy and dextroposition of the aorta, with overriding
of the VSD. Blood shunts from the right to the left through the VSD,
allowing unoxygenated blood to mix with oxygenated blood resulting in
cyanosis.
2.3.4 Trunkus arteriosus
This consists of the following
a) Outlet VSD
b) Single semilunar valve
c) Common arterial root that overrides the ventricular septum
The ventricular root usually originates from the 2 ventricles equally. It
can originate more from one ventricle than the other. The truncal valve
(semilunar valve) may have one to six leaflets. It can have normal flow
regurgitation or stenosis.
38
There are 3 types of truncus arteriosus. In all 3 types, the pulmonary
artery comes off the aorta. It can be the main pulmonary artery or one or
both branches of the pulmonary artery. The position of their origin
determines the type
2.4.0 Sonographic Assessment of Thoracic Circumference as
Prediction of Gestational Age
2.4.1 Thoracic Circumference
However, foetal thorax would be a better part of the foetal trunk to be
localized. In 1973, it was described the uses of the thoracic circumference
in the assignment of foetal growth but the landmark for the measurement
was not consistent. Garrett and Robinson (1971) in Sidney had also
reported on the measurement of foetal trunk area as a means to assess
foetal size. They had also reported in grey scale obstetric at the
International Biomedical Engineering meeting in Melbourne in the same
year. The method did not catch on until the appearance of Grey scaling in
other machines (Glasgow, Denver) and in particular Octoson in 1975. In
1976, the Hansmann group (Kugener et al., 1976) described landmark for
the measurement of the thoracic circumference. It was a similar plane as
that used for the abdominal circumference.
39
Thoracic dimensions can be assessed by measuring the thoracic
circumference at the level of the four heart chamber view of the heart
(Dugoff et al,. 1996). A study by Chitkara et al, 1987 made use of this
land mark to produce normal values of the thoracic circumference in the
prediction of gestational age.
Fig 4: Four-chamber sonograms colour Doppler. During diastole,
flow is visualized entering from both the right and left atria (RA, LA)
into the right and left ventricles (RV, LV) and the flows are
separated by the interatrial and interventricular septum.
Source: De Vore, 2009
Fig 5: Four heart chamber view and chest circumference of foetus
40
2.4.2 Examination of the foetal heart
The standard views to be obtained when scanning the heart are:
Four chamber view
The four heart chamber view is obtained by taking a longitudinal section
of the fetal thorax and then angling the transducer in such a way to fill till
the four chambers are seen (Kuldeep and Narenda,2002;).In this view, the
following are seen.
1. The prominent Eustachian valve within the right atrium and the
valve of the foramen ovale flapping within the left atrium.
2. The atrioventricular valves are seen with tricuspid valve lying
closer to the cardiac apex than the mitral valve
3. The right ventricle is situated beneath the anterior chest wall. The
moderator band is in the right ventricle and the walls are
trabeculated. The left ventricle walls are much smoother
4. The atrioventricular valve opens during diastole
The basic cardiac examination includes a 4-chamber view of the fetal
heart. If technically feasible, an extended basic cardiac examination can
also be attempted to evaluate both outflow tract. When the ultrasound
beam is directed perpendicular to the chest of the foetus and angling the
transducer in such a way that four chambers of the heart are identified.
These chambers consist of the right and left atrial and ventricular
41
chambers, with their respective valves that connect the atrial and
ventricular chambers.
2.5. 0 Sonographic Assessment of other Parameters used to
Determine the Gestational Age
There are numerous parameters established that can be used to determine
foetal growth. The parameters used in determining gestational age are;
crown-rump length, head circumference, abdominal circumference,
biparietal diameter, occipito-frontal diameter and femur length. Others
are; foetal neck circumference, foetal kidney length, foetal humerus,
foetal liver and axial transverse diameter of the fetal foramen magnum.
Some of these parameters not only determine foetal growth but weight as
well.
2.5.1 The Crown Rump Length (CRL)
The original definition of the CRL was by Mall in 1967. The CRL is the
sitting height, midbrain to the lowest point of breech. For ultrasound, the
CRL is defined as the longest length excluding the limbs and yolk sac
(Westerway et al., 2002). In dating examination performed in the first
trimester, the CRL is the optimal method of establishing fetal age
(Sanders et al., 1998). CRL is the measurement of choice less than 12
weeks and CRL measuring discrepancies are more from 12 weeks
gestation (Westerway et al., 2002)
42
2.5.2 Biparietal Diameter (BPD)
The BPD remains the standard against which other parameters of
gestational age are compared. The BPD is measured from the outer
surface of the anterior parietal bone to the inner surface of the posterior
parietal bone (Shepard and fill 1982; Hadlock et al., 1982 and Beigi and
Zarrinkoub, 2000).The anatomical landmark used to ensure accuracy and
reproducibility of the measurement include: midline falx, the thalami
symmetrically positioned on either side of the falx and visualization of
the septum pellucidum at one of the fronto-occipital distance. The
variability of BPD in predicting menstrual age after 28 weeks is too great
to be reliable (Sabbagha et al., 2003).This is the most reliable method of
estimating gestational age between the 12th and the 26th weeks. After that,
its accuracy can be lessened by pathological disorders and biological
variations that affect fetal growth.
Fig. 6: Foetal skull with Biparietal diameter sonogram (calipers) at
25 menstrual weeks. T, thalami; CSP, cavum septum pellucidum.
43
The BPD is the distance between the parietal eminences on either side of
the skull and is, therefore, the widest diameter of the diameter of the skull
from side to side using scans at different angles, the transverse section
will be recognized when the shape of the fetal is ovoid and the midline
echo from the falx cerebri is interrupted by the cavum septi pellocidi and
the thalami. When this plane is found, the gain on the ultrasound unit
should be reduced and measurement made from the outer table of the
proximal skull (the part nearest to the transducer) to the inner table of the
distal skull (the part farthest away from the transducer). The soft tissues
over the skull are not included. This is the “leading edge-to-edge”
technique (Ugwu et. al, 2007). This parameter has a variability ranging
from 1.5 to 2.7weeks depending on the period gestation (Subbarao et al.,
2003). The BPD (fig 6)was measured by from the outer edge of the skull
for the edge near to the transducer and then the inner edge of the skull
vault(Altman et al., 1997).
2.5.3 Head Circumference (HC)
It is the length of the outer perimeter of the cranium. It is measured using
the same landmark with the BPD (Hill et. al, 1991) The HC is more
accurate than the BPD in predicting gestational age (Benson and
Doubilet, 1991).This is more accurate predictor of gestational age when
the skull shape is normal (Subbarao et. al, 2003). If the cephalic index is
44
within the normal range, the BPD is acceptable as an estimate of
gestational age. If the cephalic index is outside this range (less 70 or
greater than 86), the measured BPD should not be used to determine the
gestational age .Instead the head circumference can be used(Ugwu et. al,
2007). On some ultrasound machines, this may be measured directly, it
can also be calculated(Ugwu et al., 2007). The head circumference(HC)
was measured by tradeball on the outer skull vault.
Fig.7: Head circumference sonogram
Measurements to obtain the cephalic index: outer-to-outer distance at the
level of the biparietal diameter (B) divided by occipital-frontal diameter
(o) multiplied by 100.
Head circumference = (BPD + Fronto-occipital diameter) ×1.57
Cephalic index = BPD × 100 Fronto-occipital diameter
45
A study conducted by Ugwu et al. (2007) on the Ibo tribe of Nigeria
revealed the Foetal Cephalic Index as 85.92±4.88.
2.5.4 Abdominal circumference (AC)
It is the length of the outer perimeter of the abdomen taken on axial plane
at the level of the umbilical vein-ductus venosus complex (Hadlock et al.,
1982). The variability in predicting menstrual age values associated with
a given abdominal circumference measurement is broader than that
observed with the foetal BPD (Hadlock et al., 1982). AC is less accurate
than BPD in establishing gestational age (Subbarao et al, 2003). AC is
used to detect intrauterine growth disturbances, the measurement must be
taken at the level of the fetal liver which is very sensitive to deficient
nutrition. It is most important that the scan shows a cross-section of the
foetus that is as round as possible. Make sure that the correct level is
being measured; look for the umbilical part of the left portal vein. The
measurement must be made on a trans-axial plane, where the umbilical
portion of the left portal vein enters and is entirely within the liver. The
liver should be short, not elongated. If it is also too long, the axis is too
oblique. When you have a scan at the correct level, measure the antero-
posterior (AP) and transverse diameters. A medium gain setting should be
used and measurement must be from the outer edge of the foetal abdomen
46
on one side to the outer edge on the other side. Calculate the abdominal
circumference by using the formula below.
AC = (Antero-posterior diameter + transverse diameter) × 1.57
If the abdominal circumference is less than the fifth percentile, it is small
and if greater than 95th percentile, it is large((Ugwu et al., 2007).
2.5.5 Femur length
The femur length is measured from the major trochanter to the lateral
condyle along the axis of the central shaft exclusive of epiphyses. The
long shaft of the femur is placed exactly perpendicular to the ultrasound
beam (Beigi et al., 2000). Overall, it is mostly used in the third trimester
because the BPD becomes less accurate/ reliable owing to the
engagement of the fetal head in the mother’s pelvis. This measurement is
as reliable as BPD in the determination of gestational age and it can be
used from 12 weeks to term. It is however necessary that measurement is
done when the two ends of the femur are obtained clearly and the outline
of the bone is straight (Dugoff et al., 1996). Find a projection that shows
a transverse section of one of the long bones, and then scan at 900 to this
to obtain a longitudinal section (Ugwu et. al, 2007).
47
Fig 8. Correct femur length outline sonogram
The markers outline the distal femoral epiphysis. FL, femur length
Fig. 9a: Incorrect the femur (f) length sonogram should not be
measured unless it is perpendicular to the transducer.
48
Fig.9b: Incorrect bowed femur length sonogram
The markers outline the appropriate length of the femur. (A) Curved
medial (M) border (arrows). (B) Straight lateral (L) border (arrows).
2.5.7 Other parameters
2.5. 7.1 Fetal kidney length
This is measured from the outer border of the upper pole to the outer
border of the lower pole of the kidney. Kidney length is a more accurate
method of determining the gestational age than fetal biometric indices,
BPD, HC, AC and FL between 24 and 38 weeks gestation (Konje et al.,
2002).
2.5.7.2 Humerus length
Other parameters such as Humerus length (HL) (Mastrobattista et al.,
2004), fetal spine length (Ulm et al., 1999), Thoracic length and
circumference (Chikara et al., 1987), neck circumference (Sherer et al.,
2007).
49
2.5.7.3 Average Gestational Age
This refers to the mean of more than one parameter used in estimating
gestational age. Each parameter used has a certain degree of variability
but a combination of more than one parameter reduces the variability in
weeks. The table below by Subbarao et al.(2003) illustrates the below
Table 1: Age Variability in Weeks
PARAMETERS 6-14 12-18 24-30 36-42
CRL ±0.4 - - -
BPD - ±1.2 ±2.2 ±3.2
FL - ±1.6 ±2.8 ±4.0
HC - ±1.2 ±2.1 ±2.3
AC - ±1.7 ±2.2 ±3.0
BPD,HC,AC,FL - ±1.1 ±1.8 ±2.3
2.6.0 Other Radiological Methods of Fetal Dating (Other Imaging
Modalities used for Foetal Dating)
2.6.1 Plain film
Here radiographic projections such as PA 200 cephalad in early
pregnancy centered to the tip of the coccyx. In advanced pregnancy, PA
and AP, centered respectively to the L4 and midpoint between the iliac
crests. The PA oblique could also be used.
50
2.6.2 Amniography or fetography
Here the amniotic fluid surrounding the fetus is replaced by a contrast
agent and radiographs taken. These are all obsolete and have been
superseded by ultrasound
2.6.3 Magnetic Resonance Imaging (MRI)
MRI is used as an additional investigation, mostly to detect foetal
anomalies.
2.7.0 Clinical methods of Estimating Gestational Age (Non-
Radiological Methods) According to Moongelli and Gardosi,
2008
2.7.1. Naegle’s Rule, Parikh’s Formular and the Obstetric Wheel
(Menstrual History)This is the most common method of pregnancy
dating. The expected date of delivery (EDD) is calculated by Naegele's
Rule is a standard way of calculating the due date for a pregnancy. The
rule estimates the expected date of delivery (EDD) by adding one year,
subtracting three months, and adding seven days to the first day of a
woman's last menstrual period (LMP).
Example:
LMP = 8 May 2009
+1 year = 8 May 2010
-3 months = 8 February 2010
+7 days = 15 February 2010
51
The result is approximately 280 days (40 weeks) . This method assumes
the patient has a 28 days menstrual cycle with fertilization occurring the
14th day, and many others are not certain of their last period. In addition,
early pregnancy bleeding or recent use of contraceptives may lead to an
incorrect assumption of the date of ovulation. Naegele's Rule assumes an
average cycle length of 28 days, which is not true for everyone.
However, Parikh's Formula is a calculation method that considers
considers cycle duration EDD is calculated using Parikh's Formula by
adding 9 months to LMP, subtracting 21 days, then adding duration of
previous cycles (Parikh , 2007). The obstetric wheels consist of an outer
wheel that has markings for the calendar and an inner, sliding wheel with
weeks and days of gestation.
2.7.2 Other Non-Radiological Methods (Blood, Pelvic and/or
Abdominal Palpation)
1. Methods such as measurement of the fundal height, measurement
of maternal abdominal circumference.
2. Date of pregnancy test: Determination of the blood HCG (human
chorionic gonadotrophin) concentration (in early pregnancy) have
all been replaced by ultrasound owing to lack of accuracy and
reliability.
52
3. Perception of foetal movement by the patient is called quickening,
is a relatively late sign of pregnancy occurring at 19-21 and 17-19
Weeks’ gestation in nulliparous and multiparous women
respectively.
4. Pregnancy following assisted reproduction technique, the GA of
pregnancies resulting from in vitro fertilization can be precisely
calculated from the time embryo implantation
53
CHAPTER THREE
RESEARCH METHODS
3.1 Introduction
3.2 Research Design
The research was a prospective cross sectional study. The human subjects
chosen for the study were consented pregnant women from 2nd and 3rd
trimesters referred for obstetric scan from the clinic at University of
Maiduguri Teaching Hospital (UMTH) who met the inclusion criteria.
3.3 Setting of Study
The study was conducted at University of Maiduguri Teaching Hospital,
Borno State, North eastern Nigeria. University of Maiduguri Teaching
Hospital (UMTH) in 1974 the defunct North East government conceived
the construction of a specialist Hospital in Maiduguri Nigeria, the state
capital. The federal military government later took over and completed
the project. The first patient was admitted on 18th February, 1982. The
hospital covers a landmark of about 64,773 hectare. The hospital was
designated a centre of excellence in immunology and infectious diseases
by the federal government of Nigeria. It is 540 bedded hospital.
The UMTH main functions are Provision of quality tertiary health care
services, Provision of training of medical and other health professionals
and Research. The hospital serves the North East sub-region of the
54
country, comprising (Adamawa, Bauchi, Borno, Gombe, Taraba and
Yobe) and entire nation as well as a sizable number of people in
neighboring countries, Cameroon, Chad and Niger Republics.
Radiology department facilities
The department has different imaging modalities and therapeutic units
such as MRI, CT-Scan, Mammography, C-Arm, fluoroscopy,
conventional x-ray and interventional angiography, ultrasound unit which
are all Vamed projects (2005). Furthermore, it is regional
ultrasonography training centre for West Africa in collaboration with
Jefferson ultrasound research and education institute (JUREI),
Philadelphia, U.S.A.
3.4 Study Population
A sonographic assessment of uncomplicated singleton pregnancies from
15-41 weeks’ gestation was done. The period of gestation from which
measurements were obtained were divided in to 27 weeks. Maiduguri
consist of many tribes ,however 28 tribes participated in the study
including three major tribes Igbo, Hausa and Yoruba.The major tribe is
Kanuri .Two major religion are predominant Christians and Muslims in
this region. The social life of the people are characterized by early
marriage by the female from 15 years old and polygamy is a common
practice.
55
3.5 Determination of Sampling Size and Sampling Technique
Sample size, n = Z2P (1-P) / d2 Taylor’s formula
n = minimum sample size
Z = 1.96 standard normal deviation usually set at 95%
confidence level
P = estimated population. Since this proportion is not
known for the target population, a value of 50% (0.5)
is assigned to obtain maximum value for P
d = absolute precision required on either size of the
proportion 5% (0.05)
n = (1.96)2 x 0.5 (1 – 0.5) = 384 (0.05)2
Hence a sample size of 907 participants were chosen for the study which
was greater than calculated minimum sample of 384. This allows for
reduction of sampling error. The sampling technique used was convenient
sampling, this entails any eligible pregnant women referred for fetal
dating ultrasound scan that met the inclusion criteria was included for the
study.
3.6 Sources of Data
The data was a primary sources. These are measurement of Nigeria
populations of derived foetal thoracic circumference, the biparietal
diameter (BPD), femur length (FL), abdominal circumference (AC) and
56
head circumference (HC) of foetus of 907 pregnant women other sources
of data and information which are secondary are from books and journals
of Caucasians such as TC for comparative analysis.
3.7 Ethical Consideration
The ethical committee provided clearance for this study (approval
number ADM/TH/75/VOL.II and date 08/08/2007) and all women
provided written consent to participate.
3.8 Recruitment of Subjects
The subjects were pregnant Nigerian women from their mid trimester of
pregnancy (15 weeks to 41 weeks) who were referred for ultrasound
investigation.
Inclusion criteria
• Pregnant women at their mid-trimester (15weeks -41 weeks )
• No history of prolonged maternal illness
• No vaginal bleeding
• Singleton pregnancy
• No other abnormality visualized on either maternal or fetal parts
ultrasonically.
57
Exclusion criteria
• Women who take drugs and substance abuse – smoking, alcohol,
anti-hypertensives, fertility drugs.
• Women with uterine and placental anomalies and abnormalities –
Bicornuate uterus, uterine myomas, septate uterus.
• Fetal infection.
• Maternal conditions: Diseases – diabetes and Hypertension
women.
3.9 Method of Data Collection
The age, tribe and parity of the women were also recorded on data
capture sheet. The data was collected by taking measurements of two
fetal thoracic diameters at right angle to each other and later thoracic
circumference derived with a formulae(TC=��{ (D12+D2
2)/2}). Those
measurements were taken at the level of the four heart chamber view and
during diastole. Apart from fetal thoracic diameters, the BPD, HC, AC
and FL were also measured.
58
Fig. 10: Sonographic appearance of derived thoracic circumference
3.9.1 Instrumentation
Measurement were obtained with a modern real-time ultrasound
(ALOKA prosound 3500, produced in Japan) two-dimensional real-time
gray scale ultrasound machine with good resolution equipment. The
equipment less than 30 months old from date of manufacturing (2005)
was used, with a 3.5MHz transabdominal curvi-linear transducer. The
electronic calipers calibrated for an assumed ultrasound velocity of
1540m/s in soft tissue. The equipment has a calibration which reading of
the GA as measurements were made and give a composite (average) GA.
3.9.2 Patient Preparation
1. Full urinary bladder was achieved by giving 1 litre of water
ingested within 15 to 20 minutes time period to the subject.
D1
D2
59
2. If for any reason the patient cannot have fluids, sterile water were
used to fill the bladder through a Foley’s catheter by obstetrician or
Radiologist.
3. The patient were positioned supine with 3.5MHz transducer.
4. The patient breathing technique were normal respiration.
3.9.3 Scanning Protocols
The procedure was explained to each patient and the subject was asked
to take a litre of water in order to achieve a full bladder. Once a patient
has full bladder, the examination was commenced with transabdominal
scan. A research assistant (experienced 19 years, registered AIUM
sonographer) was used. Technique adopted was
the STANDARD ultrasound examination of the foetus of these three
organizations (AIUM–ACR-ACOG, 2007). The fetus were scanned at
various tomographic planes for best technique to demonstrate the thoracic
circumference of the foetal chest dimensions, after applying Ultrasound
gel on the abdomen. The foetuses were scanned in both longitudinal and
transverse axis using transabdominal probe at plane to identify the lie
and presentation of the foetus. The foetal well being accessed by
examining the fetal heart and other indicators.
60
3.9.4 Scanning Technique to Demonstrate Fetal Thoracic
Circumference
The patient lies either supine (in early pregnancy) or in Foyler position
i.e. 55o caudad angulation on the examination couch. A general survey
(sweep) using a 3.5MHz transducer was initially performed to ensure
that the foetus, the placenta and the uterus were normal. The foetal four
heart chamber view was used as landmark for measurement of the fetal
thoracic circumference according to De Vore, 2009. The four chambers
were identified when the ultrasound beam was directed at right angle to
the foetal chest (Chitkara et. al. 1987; De Vore, 2009).
Fig. 11: Imaging the four-chamber view is accomplished by directing the ultrasound beam perpendicular to the fetal chest. At this level, the four-chamber view is identified. This view contains the right atrium (RA), left atrium (LA), right ventricle (RV) and left ventricle (LV). Source: De Vore, 2009
To obtain the four chamber view of the fetal heart, the long axis of the
spine was identified. Then the transducer rotated 900 at the level of the
61
foetal thorax. Or from the abdominal circumference, the transducer was
gradually angled cephalad. Sliding up towards the head until the required
four heart chamber view was obtained (Chikara al. 1987,Sanders et al.,
1998). In the four chamber view one sees the prominent Eustachian valve
within the right atrium and the valve of the foramen ovale flapping within
the left atrium (Kuldeep et al ., 2002). The atrioventricual valves are seen
with the tricuspid valve lying closer to the cardiac apex than the mitral
valve (Kuldeep et al., 2002).
The image was frozen during diastole i.e. when both the tricuspid and
mitral valves are open. The data were obtained by measuring two foetal
thoracic diameters at right angle to each other than thoracic
circumference was derived.
Fig. 12: This illustrates the level that the four-chamber view is imaged (green). The main pulmonary artery (MPA), ductus arteriosus (DA), and the aorta (AA) are not imaged at the level of the four-chamber view. SVC=superior vena cava, RV=right ventricle, RA=right atrium, LV=left ventricle, LA=left atrium Source: De Vore, 2009
62
One diameter (D1) was taken along the ventricular septum. The other (D2)
was taken along the line joining the mitral and tricuspid valves. Both are
taken from outer to outer fetal thoracic surfaces in such a way that they
are at right angle to each other as illustrated in the diagram below.
Fig.13: Illustration of two diameters used to drive the thoracic circumference
Fig. 14: Sonographic appearance of thoracic circumference with the
four-chamber view of the fetal heart
Thus from D1 and D2The foetal thoracic circumference was derived using
this formular.
TC=��{ (D12+D2
2)/2}
D1
D2
Heart
Fetal thoracic circumference
D1
D2
Thoracic circumference
63
It was assumed that the thoracic at the four heart chamber view is either
circular or oval in shape as the foetal head at the standard landmark for
BPD’s measurement. These formular applied to the calculation of the
head circumference were also applied to the foetal thoracic
circumference.
Other parameters measured
The BPD the proximal edge to the proximal edge of the deep border
(outer-inner) (Altman et al., 1997; Ugwu et. al, 2007) at the standard
landmark as described in chapter two.
The head circumference (HC) was measured by tradeball on the outer
skull vault (Ugwu et. al, 2007).
Abdominal circumference (AC) it is the length of the outer perimeter of
the abdomen taken on axial plane at the level of the umbilical vein-ductus
venosus complex (Hadlock et al., 1982).
The femur length was measured from the major trochanter to the lateral
femoral condyle along then longest axis of the central shaft exclusive of
the epiphyses as described by (Beigi et al., 2000)
The following information items were collected from each of obstetric
case scanned in data capture sheet.
64
1. Patient age, tribe, parity
2. Biparietal diameter (BPD)
3. Derived Fetal thoracic circumference (TC)
4. Fetal head circumference (HC)
5. Fetal femur length (FL)
6. Abdominal circumference (AC)
7. Average gestational age (AGA)
The measurement were taken from the 15th -41 weeks’ of GA .
3.10. Dating Model
Due to some factors such as faulty memory, bleeding in early pregnancy
and the use of contraceptives the LMP as a gold standard has several
potential of inaccuracy (Campbell et al., 1985; Apfel and Green, 1999;
Chuldleigh and Thilaganathan,2004;Agwu et al. 2008). Also with the
illiteracy of many women in the locality of the study, which the majority
doesn’t know their LMP. For these reasons the LMP was not used. Rather
the measurements were correlated to the composite (average) gestational
age obtained from the BPD, HC, AC and FL. This is because the
combination of more than one parameter increases the reliability,
sensitivity and accuracy of foetal biometry (Mercer et al., 1987; Ogunsina
et. al., 2001; Subbarao et al., 2003)
65
3.11 Method of Data Analysis
The analysis of the data involved the use of test statistics. The package
SPSS version 17.0, was used in the analysis. All comparative tests were
performed at 5% significant level. The analyses were done using both
descriptive and inferential statistics. Descriptive statistics used include
frequency, standard deviation, percentage, means, range geometric mean,
tables and charts were used to describe the data Inferential statistics used
include Student ‘t’ test was used to test the average means values and
Pearson correlation coefficient was used to show relationships between the
TC and BPD, HC,AC, FL and weeks of gestation. Geometric mean was used to
calculate the growth rate.
66
CHAPTER FOUR
PRESENTATION OF RESULTS AND DISCUSSION
4.0 Introduction
The results obtained from the measurements were analysed and
presented. The mean of the several biometric parameters were measured
were analysed and presented. The mean measurement were BPD, FL,
HC, AC and TC. The mean values of the measured biometric parameters,
BPD, FL, HC,AC, TC were compared and correlated with each other, to
ascertain their statistically acceptability.
4.2 Results
4. 2.1 Demography
Descriptive analysis of data
A total of 907 singleton women participants were employed in the study. The
TC values ranged from 9.159cm to 32.168cm within 15-41 weeks of as
gestation demonstrated in table 4.Twenty eight different tribes were involved
in the study, the major tribes were Kanuri 299(30.97%), Igbo176
(18.07%),Fulani80(8.82%),Hausa32(3.80%), Marghi 17(1.87%) as
shown table 2. Their age ranged from 15 to 42 (mean age is 32).
67
Table 2: Distribution of the participants according to tribe S/NO. TRIBE FREQUENCY PERCENTAGE
1. Babur 9 0.96 2. Bade 8 0.94
3. Bago 9 0.96
4. Baseyap 9 0.97
5. Bura 13 1.93
6. Chibok 9 0.95
7. Daba 8 0.94
8. Dajju 8 0.94
9. Fulani 80 8.82
10. Hausa 32 3.80
11. Hidi 9 0.96
12. Idoma 21 2.31
13. Igala 8 0.93
14. Igbo 176 18.07
15. Jukun 8 0.94
16. Kanakura 9 0.95
17. Kanuri 299 30.97
18. Kilba 8 0.94
19. Kuteb 6 0.71
20. Mandara 10 0.82
21. Marghi 17 1.87
22. Michika 9 0.97
23. Nakere 8 0.94
24. Shuwa 43 4.12
25. Tiv 10 0.72
26. Waja 8 0.94
27. Yabe 8 0.94
28. Yoruba 65 7.17
Total 907 100 The majority of pregnancies were between 30 and 40 weeks old
(151=46.6%). The distribution of the scanned women according to the
pregnancy age is illustrated in fig 15
68
Fig 15: Age distribution of the participants
This shows that majority of women age group scanned (20-24 age)
Was 88.07%, while the least age group was 40-42 age 6.03%
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69
Fig 16: Gestational age distribution of foetus in weeks
This shows that majority of the group foetal gestational age measured
was 46% (30-40). While the least group of foetal gestational age was
22% (12-20).
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Table 3: Mean values of TC matched against GA
S/N G.A (WEEKS) FREQUENCY TC MEAN VALUES(cm)
S.D.
1 15 16 7.9357 0.243 2 16 13 8.812 0.398 3 17 24 9.795 1.091 4 18 24 12.310 0.785 5 19 14 12.863 0.726 6 20 32 14.054 1.798 7 21 45 15.330 1.455 8 22 62 15.342 1.249 9 23 26 16.857 0.293 10 24 39 18.212 1.942 11 25 59 18.508 0.961 12 26 41 18.589 0.950 13 27 44 20.964 1.190 14 28 22 20.971 1.664 15 29 48 22.327 1.254 16 30 32 23.336 1.080 17 31 22 24.871 2.468 18 32 11 25.771 0.903 19 33 18 25.929 0.000 20 34 52 26.104 0.926 21 35 72 26.891 1.811 22 36 48 26.924 1.006 23 37 65 27.137 2.224 24 38 31 27.160 0.846 25 39 14 27.410 2.179 26 40 16 31.271 0.162 27 41 17 32.381 0.162
The table above showed the measured mean values of TC matched
against GA. The frequency distribution and their standard deviations.
71
Fig17: Scatter diagram of mean TC against weeks of gestation.
The equation of the line of ‘best fit’ is Y=4.65 + 1.13TC .Where Y is the
average gestational age and X is the fetal thoracic circumference There is
a high correlation and statistically significant correlation was observed
between the weeks of gestation and the TC (r2=0.974, P�0.001)
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TABLE 4: Comparism between 50th percentile TC in Nigerians
(derived nomogram) and the caucasians
The above showed the comparism of TC in Nigeria an the Caucasians at
50th percentile
S/N GA (WEEKS)
Number of measurements (Caucasian)
TC (cm)Caucasian 50 percentile
Number of measurements (Nigerian)
TC(cm)Nigerian derived 50 percentile
1 16 06 9.1 13 8.812
2 17 22 10.0 24 9.795
3 18 31 11.0 24 12.310
4 19 21 11.9 14 12.863
5 20 20 12.8 32 14.054
6 21 30 13.7 45 15.330
7 22 18 14.6 62 15.342
8 23 21 15.5 26 16.857
9 24 27 16.4 39 18.212
10 25 20 17.3 59 18.508
11 26 25 18.2 41 18.589
12 27 24 19.1 44 20.964
13 28 24 20.0 22 20.971
14 29 24 21.0 48 22.327
15 30 27 21.9 32 23.336
16 31 24 22.8 22 24.871
17 32 28 23.7 11 25.771
18 33 27 24.6 18 25.929
19 34 25 25.5 52 26.104
20 35 20 26.4 72 26.891
21 36 23 27.3 48 26.924
22 37 22 28.2 65 27.137
23 38 21 29.1 31 27.160
24 39 07 30.0 14 27.410
25 40 06 30.9 16 31.271
73
4.3 Inferential Analysis
4.3.1 Test of Hypothesis
H0: There is no significance difference between the mean thoracic
circumference of Nigerian from that of the Caucasian population.
HI: There is significance difference in the mean thoracic circumference
of the Nigerian from that of the Caucasian population.
Student T Test: Two tail
P=0.716913 > 0.05
Therefore, H0 is accepted and HI is rejected
4.4 Fetal Thoracic Circumference Growth Rate
Geometric mean= 0.3874cm/week. The Growth rate at the second
trimester was 0.8169/week and third trimester 0.8217/week
4.5 Prediction of GA From TC
Predictive equation: y = 4.65 + 1.13(TC)
y = gestational age in weeks
x= thoracic circumference
74
TABLE 5: Predic5ted GA from equation 75th Percentile in Nigerians
GA = 4.65 + 1.13 TC S/N GA (WEEKS) TC
1 15 9.1590
2 16 10.044
3 17 10.929
4 18 11.814
5 19 12.699
6 20 13.584
7 21 14.469
8 22 15.354
9 23 16.239
10 24 17.124
11 25 18.009
12 26 18.894
13 27 19.779
14 28 20.664
15 29 21.549
16 30 22.434
17 31 23.319
18 32 24.204
19 33 25.088
20 34 25.973
21 35 26.858
22 36 27.743
23 37 28.628
24 38 29.513
25 39 30.398
26 40 31.283
27 41 32.168
The above table 4 shows the novel TC nomogram from the Nigerian
population
75
Fig.18: Scatter diagram of TC against BPD. There was a highly positive
correlation and statistically significant correlation is noted between the
TC and BPD (r2=0.9824, P � 0.001).
There is high strong correction between the TC and other biometric
parameters such as BPD, HC, AC and FL.
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Fig.19: Scatter diagram of TC against HC. There was a highly positive
correlation and statistically significant correlation is noted between the
TC and HC (r2=0.9806, P � 0.001)
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Fig.20: Scatter diagram of TC against AC. There was a highly positive
correlation and statistically significant correlation is noted between the
TC and AC (r2=0.9712, P � 0.001).
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Fig. 21: Scatter diagram of TC against FL. There is a highly positive
correlation and statistically significant correlation is noted between the
TC and FL (r2=0.9862, P � 0.001)
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TABLE 6: Regression model for TC against BPD, FL, HC.
Using the formula Y = a+bx
S/N Y X A B R
Dependent Variable
Independent Variable
1 TC BPD 1.07 4.08 97.40%
2 TC FL 5.67 4.33 98.62%
3 TC HC 1.64 0.99 98.06%
Table 7: Gestational age groups and their coefficient of
determination
Gestational age group Coefficient of determination
15 – 23 0.8050
24 – 32 0.7832
33 – 41 0.7182
The gestational age group and their respective coefficient of
determination are presented in table above. The foetal GA 15-23 weeks is
more accurate (80.50%) than 24-32 and 33-41 weeks 78.32% and 71.32%
respectively in table 6.
80
4.6 Discussion
The study involved 907 pregnant women between the ages of 15 and 42
years and TC values range from 9.157-32.168cm within 15-41 weeks of
GA. The majority of the participants were women between 20-24 (87%)
years. The minimum age of 15 years shows that girls in the region marry
at a very young age (Fig.16). The minority were 40 years and above, this
because of climacteric period The tribe that dominated the study was the
kANURI (30.97%) because Kanuri is the major tribe in this locality,
followed by the Igbo’s (18.07%) because they are more enlighten and
seek health care. The Table 2 also shows the diverse ethnic groups in the
country even though it was just a few that were represented in the study.
This study showed that there was no significance difference in the TC of
population studied and that of the Caucasian population which is not in
line with the findings of Matrobattista et al (2004).
The study showed that there was a linear relationship between TC and the
weeks of gestation which is in line with the findings of Chitkara et
al(1987). Therefore, the values of the Caucasian population can be used
on locality studied population.
The majority of women scaned were between 30 and 40weeks pregnant
(fig 16). At this period of time, the foetus is well developed and has
already grown to some extend therefore making the accurate dating
81
difficult (Ohagwu et. al., 2009). According to Agwu et al. (2008),
optimal information is obtained when the scan is carried out between the
14th and the 18th week of gestation. Also, the second trimester pregnancy
scan is best performed at 18-20 weeks of pregnancy mainly to look for
congenital malformation, when the foetus is large enough for an accurate
survey of foetal anatomy, multiple pregnancies can be firmly diagnosed
and dates and growth can also be assessed(Ola-oja, 2005).
The data presented in Table 4 shows the normal values of the foetal
thoracic circumference which can be used to determine the gestational
age. The data analysis also shows that there is a strong correlation (r2=
0.974) between the fetal thoracic circumference and the gestational age .
This agrees with finding Chitkara et al.,(1987). They found that there was
a close correlation (r2 =0.94) between the fetal thoracic circumference and
the gestational age in normally growing fetuses. This therefore means
that the fetal thoracic circumference can be used reliably as a predictor of
the gestational age in the 2nd and 3rd trimester. Though several parameters
are used to determine the gestational age, fetal thoracic circumference can
be used when it is difficult to get the accurate view for the measurement
of other parameters. Also this can be added to them so as to have many
parameters used to determine the gestational age as it is important to find
new parameters to measure foetal growth that correlate with fetal age.
82
The fetal thoracic circumference grows linearly with the gestational age.
This is expressed by the line of best fit obtained using the method of least
square. This equation(Y= 4.65 + 1.13TC) can easily be used to determine
the gestational age. This was used in prediction of the gestational age
were table 4 of foetal thoracic circumference and gestational age is not
available.
The fetal thoracic circumference is more accurate in determining the
gestational age between 15 and 23 weeks of gestation and this accuracy
reduces as the pregnancy progresses. This agrees with finding who found
that the earlier the ultrasound assessment, the more accurate the
prediction of the date of delivery.
The average fetal thoracic circumference growth rate per week was
0.3874cm. This value should be used to assess normal foetal growth thus
any intra-uterine growth retriction (IUGR) and overgrowth can be
diagnosed. Most of the women scaned were between 30 and 40 weeks
pregnant. This the period at which the thoracic circumference is less
accurate (Ola-oja, 2005). This will therefore lead to less precise
gestational age prediction. It is necessary for the women to come for
prenatal ultrasound scan in early pregnancy so that an accurate prediction
of gestational age can be made.
83
CHAPTER FIVE
SUMMARY AND CONCLUSIONS,
5.0 Summary of Major Findings
Majority of the women coming for ultrasound scan were between 20 and
24 years old. Majority of the women scanned were between 30 and 40
weeks of GA, this is the period at which the fetal thoracic circumference
is less accurate in predicting the gestational age.
A nomogram is drawn to determine the gestational age based on the fetal
thoracic circumference. This normative value have no statistical
difference with Caucasian values. The thoracic circumference is more
accurate in determining the gestational age between the 15 and 23 weeks
of gestation and its accuracy decreases as the pregnancy progresses.
There is a strong linear correlation between the TC and the BPD, HC,AC
and FL with these values respectively (r2= 0.9740, P�0.001), (r2= 0.9824,
P�0.001),(r2= 0.9806, P�0.001), (r2= 0.9712, P�0.001), (r2= 0.9862,
P�0.001).
The equation for determining the gestational age based on foetal thoracic
circumference is Y= 4.65 + 1.13TC.
The accuracy of TC in predicting GA is 97.40% while those of BPD, HC,
AC and FL accuracy were 98.24%, 98.06%, 97.12% and 98.62%
respectively. There was no statistically significant differences between
84
TC and others (BPD, HC, AC, FL) established biometric parameters in
predicting GA. The average growth rate is Geometric mean=
0.3874cm/week.
5.1 Conclusion
There is a linear relationship between TC and the gestation age at a
growth rate of 0.3874cm per week. Statistically, there is no significant
difference between the TC of population studied and that of Caucasian
population even though they from different ethnic groups and race.Hence,
Caucasian nomogram can be used as TC dating model with this evidence
based study. The study has derived a nomogram of fetal thoracic
circumference in Nigerian population and shown that the fetal thoracic
circumference is a good predictor of gestational age especially in early
second trimester.
5.2 Recommendation Based on the Finding
The nomogram of thoracic circumference of fetus developed should be
used for more accurate dating of pregnancies sonographical, especially
thoracic sparing IUGR because it is more reliable and accurate in early
second trimester. Thoracic circumference model of dating should be used
due to ease of identifying landmarks for measurement using the four heart
chamber view.
85
5.3 Study’s Contributions to Knowledge
A Sonographic nomogram of fetal chest circumference prediction of GA
has been developed. Fetal chest growth rate of local population studied is
0.3875cm/week. The regression equation is y = 4.65 + 1.13TC, this can
be used to predict the GA when the TC chart is not available.
5.4 Areas of Further Studies
A study to derive normative thoracic ratio from thoracic circumference
and thoracic length and/or thoracic circumference and abdominal
circumference of local population as indicator of abnormal fetal growth
should be studied.
86
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obstetrics and gynaecology. Available at http://www.ob.ultrasoundac_historical.html.
91
Yusuf, N., Moslem, F., Naque, J., (2007).Fetal Kidney length as a predictor of gestational age. Journey of Teachers Association, Rajshahi ; 20:1017-1018
Zegers-Hochschild, F., Nygrenk, G., Adamson, G., et. al., (2006). The
ICMART glossary on ART terminology. Human reproduction Vol. 21, No. 8 pp. 1968-1970
92
APPENDIX I
93
APPENDIX II
PARTICIPANT CONSENT FORM
RESEARCH TITLE: SONOGRAPHIC ASSESSMENT OF FOETAL
THORACIC CIRCUMFERENCE AS A PREDICTOR OF
GESTATIONAL AGE IN A NIGERIAN POPULATION
1. BACKGROUND INFORMATION
This is a request form to consent to be participant in a study titled:
Sonographic Assessment of Foetal Thoracic Circumference as a Predictor
of Gestational Age in a Nigerian Population.
The research finding generated by this study will aid in best estimate of
gestational age (GA) of pregnant women from the second and third
trimester.
The research finding will be valuable to health care practitioner’s in
predicting more accurate GA and Foetus at risk, thus prompt and better
management of women at risk by doctors.
2. VOLUNTARY NATURE OF THE STUDY
The participation is voluntary in nature. You have the right to refuse
participation and/or withdraw at any point during the study. This decision
will not affect your current and future relationship with the hospital.
3. STUDY RISK
There is no evidence that ultrasound scan posses risk to the foetus and/or
the mother. It is a reliable imaging modality for assessing foetal GA.
94
4. COST ADDITION
There is no financial cost to you for consenting to participate in this
study. As a participant, the study will be part of your normal obstetric
scan which you have already paid for prior to the scan.
5. CONFIDENTIALITY
Your identity will not be included and revealed as part of the study
gathering and it is impossible to identify you in any way after gathering
the data. The records are private. All information obtained will be
handled with strick confidentiality.
6. FEEDBACK
My name is Nwobi Chigozie, the researcher, I can be contacted through
the GSM no. 08034545811 or my Supervisor, Prof. K.K. Agwu via
07089585847
7. STATEMENT OF CONSENTS
I agreed that I have read and understood the content of the consent form
(or some one read and explained the study in my local language: Hausa,
Kanuri, e.t.c.). I am aware of the nature and benefit of this study and my
questions have been answered to my satisfaction .Hence, I hereby give
my consent to be a participant to this study.
....................................................... ……………………. Signature of participant/ thumb print Date ....................................................... ……………………. If applicable, Interpreter’s signature Date
....................................................... ……………………. Signature of researcher Date
95
APPENDIX III
Table 8: Mean values of BPD, FL, HC and TC with GA
S/N Number of measurements
(weeks) G.A
BPD (cm)
FL (cm)
HC (cm)
TC (cm)
1 16 15 15.000 1.9500 12.400 7.9357 2 13 16 21.00 2.154 14.28 8.812 3 24 17 17.000 2.3667 14.467 9.795 4 24 18 17.000 2.7583 15.750 12.310 5 14 19 18.000 2.9286 17.457 12.863 6 32 20 18.562 3.4438 17.556 14.054 7 45 21 19.378 3.6422 19.729 15.330 8 62 22 20.823 3.8177 20.956 15.342 9 26 23 24.346 4.331 23.396 16.857 10 39 24 22.872 4.4667 23.787 18.212 11 59 25 23.390 4.6017 24.039 18.508 12 41 26 23.537 4.9000 25.007 18.589 13 44 27 26.091 4.9227 26.595 20.964 14 22 28 27.364 5.2273 27.127 20.971 15 48 29 27.092 5.8158 28.717 22.327 16 32 30 27.231 5.8125 29.181 23.336 17 22 31 28.091 5.9364 30.391 24.871 18 11 32 29.909 6.109 31.173 25.771 19 18 33 30.033 6.2444 31.256 25.929 20 52 34 30.377 6.6058 32.919 26.104 21 72 35 33.053 6.8056 34.326 26.891 22 48 36 33.192 6.948 35.21 26.924 23 65 37 33.215 7.1062 35.943 27.137 24 31 38 33.313 7.2000 35.990 27.160 25 14 39 33.571 7.4000 36.286 27.410 26 16 40 40.000 7.8500 37.200 31.271 27 17 41 41.000 8.0529 38.406 32.381
96
APPENDIX IV
Table 9: Comparison of mean values of TC and HC against GA
S/N G.A (WEEKS) MEAN TC (cm) S.D MEAN H.C S.D. 1 15 7.9357 0.2434 12.400 0.103 2 16 8.812 0.398 14.28 8.66 3 17 9.795 1.091 14.467 0.255 4 18 12.310 0.785 15.750 0.465 5 19 12.863 0.726 17.457 0.051 6 20 14.054 1.798 17.556 0.559 7 21 15.330 1.455 19.729 0.624 8 22 15.342 1.249 20.956 0.497 9 23 16.857 0.293 23.396 4.837 10 24 18.212 1.942 23.787 1.868 11 25 18.508 0.961 24.039 0.533 12 26 18.589 0.950 25.007 0.729 13 27 20.964 1.190 26.595 1.474 14 28 20.971 1.664 27.127 0.554 15 29 22.327 1.254 28.717 0.519 16 30 23.336 1.080 29.181 0.263 17 31 24.871 2.468 30.391 0.252 18 32 25.771 0.903 31.173 1.462 19 33 25.929 0.000 31.256 0.051 20 34 26.104 0.926 32.919 0.510 21 35 26.891 1.811 34.326 1.508 22 36 26.924 1.006 35.21 7.11 23 37 27.137 2.224 35.943 3.386 24 38 27.160 0.846 35.990 0.432 25 39 27.410 2.179 36.286 0.616 26 40 31.271 0.162 37.200 0.103 27 41 32.381 0.162 38.406 0.103
97
APPENDIX V
Fig. 22: Sonogram of foetal thoracic circumference. Source
Manjuganesh
98
AAPPPPEENNDDIIXX VVII
DDAATTAA CCAAPPTTUURREE SSHHEEEETT
S/NO AGE TRIBE PARITY TC D1
TC D2
B̀PD BPD GA
AC FL HC LMP AGA
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
99
22
23
24
25
26
27
28
29
30
31
32
33
34
35
KKEEYY:: TTCC == TThhoorraacciicc cciirrccuummffeerreennccee,, BBPPDD == BBiippaarriieettaall ddiiaammeetteerr,, HHCC == HHeeaadd
cciirrccuummffeerreennccee,, AACC == AAbbddoommiinnaall cciirrccuummffeerreennccee,, FFLL == FFeemmuurr lleennggtthh,, LLMMPP == LLaasstt
mmeennssttrruuaall ppeerriioodd,, AAGGAA == AAvveerraaggee ggeessttaattiioonnaall aaggee..
100
AAPPPPEENNDDIIXX VVIIII
RRAAWW DDAATTAA SSHHEEEETT
S/N
1
AGE
2
TRIBE
3
PARITY
4
BPD
8
BPD
GA
9
AC
10
FL
11
HC
12
LMP
13
Average
GA
14
5
D1
6
D2
7
TC
1 28 1 7.2 6.9 21.4 7.3 24w4d 23.8 5.3 28.1 6/2/8 24wks
2 29 Marghi 3 6.9 6.0 19.6 7.0 26w5d 23.6 5.2 28.5 2w2ds
3 30 Ibo 4 8.3 9.9 27.6 8.6 33w3d 31.3 7.4 34.6 13/12/07 38w6d
4 20 Mandara 4 3.7 3.3 10.6 3.8 17w 11.4 2.5 15.1 17w5d
5 22 Kanuri 1 5.6 6.4 18.2 5.7 22w3d 20.6 4.8 24.3 26w3d
6 18 Labda 1 6.4 5.3 17.7 5.5 21w5d 19.0 4.7 24.0 25w4d
7 30 Ibo 2 4.0 4.3 12.6 4.3 18w1d 14.3 3.1 16.9 19/4/08 19w5d
8 25 Hausa 3 6.8 6.3 19.9 7.2 27w1d 23.1 5.3 28.0 15/2/08 28w4d
9 22 Igala 1 7.4 6.5 13.9 7.1 27w 24.8 5.9 30.1 31w2d
10 21 Hausa 1 5.0 4.6 14.5 5.1 20w5d 16.1 3.5 19.7 21w4d
11 20 Kanuri 0 6.8 6.9 20.8 7.0 26w4d 24.8 5.5 28.9 30w2d
12 40 Kilba 2 11.4 9.8 32.2 9.2 35w4d 39.4 8.2 36.5 11/12/07 Out of r.
13 20 Marghi 0 8.5 10.3 28.5 8.7 33w3d 29.6 7.0 34.9 37w7d
14 18 Kanuri 1 7.2 5.9 19.9 6.7 26w4d 22.3 5.0 25.6 37w2d
15 22 Hausa 0 5.3 5.6 16.5 5.4 23w4d 19.3 4.4 21.8 16/3/08 23w5d
16 32 Kanuri 5 4.9 4.5 14.2 4.9 20w1d 15.9 3.6 19.8 23/4/08 21w4d
17 29 Igbo 2 5.6 5.7 17.1 5.3 21w2d 17.9 3.8 21.2 22w6d
18 24 Fulani 0 6.1 5.7 17.9 6.1 22w4d 19.3 4.8 24.3 07/3/08 26w
19 32
32
Fulani
Fulani
9
9
7.1
7.6
8.2
8.3
23.2
24.1
8.0
7.7
30w
29w
27.3
25.5
6.4
6.1
32.8
31.6
29/12/07
29/12/07
34w1d
32w3d
20 30 Igala 6 4.0 4.7 13.2 4.2 18w 14.6 3.1 17.4 27/4/07 19w5d
21 17 Fulani 0 5.2 4.6 14.8 5.0 20w3d 16.2 4.1 21.1 22w3d
22 20 Fulani 0 5.1 4.7 14.8 5.2 21w0d 15.9 3.6 20.8 20/4/08 21w3d
101
23 25 Igbo 0 8.0 7.9 24.1 9.0 34w3d 32.0 6.6 36.7 27/12/07 36w2d
24 24 Kanuri 0 9.4 8.2 26.7 8.6 32w2d 31.7 7.1 34.8 371d
25 38 Kanuri 8 5.1 5.4 15.9 5.6 22w5d 16.2 3.8 22.0 28/7/08 22w3d
26 27 Shuwa 0 8.0 8.6 25.2 8.5 32wks 28.0 6.7 34.6 2/2/08 36w3d
27 25 Kanuri 0 7.5 9.0 25.0 8.3 31w2d 28.4 6.5 32.8 34w5d
28 29 Kanuri 4 6.2 5.6 17.9 5.8 22w5d 19.5 4.4 22.7 24w4d
29 26 Kanuri 2 8.3 8.0 24.7 9.0 34w2d 27.7 6.8 33.4 24/1/08 35w0d
30 20 Kanuri 0 9.5 9.2 28.4 8.0 29w6d 30.0 7.0 32.6 36w1d
31 38 Shuwa 6 9.4 9.4 28.5 8.7 33w1d 31.0 7.3 34.8 1/1/08 38w5d
32 30 Babur 7 8.3 7.6 24.1 8.5 32w2d 29.1 6.7 33.6 20/12/07 39w0d
33 27 Kilba 0 10 10.6 31.3 8.8 33w4d 31.8 7.3 36.5 24/12/07 35w0d
34 34 Glabda 6 9.8 8.0 27.0 8.6 32w2d 29.8 7.7 35.1 2/2/08 35w2d
35 34 Igbo 2 8.7 8.3 25,8 8.4 31w5d 33.4 7.0 34.4 01/8/08 32w6d
36 46 Mandara 11 9.1 8.2 26.2 7.9 29w5d 29.2 6.3 32.0 01/6/08 16w0d
37 29 Kanuri 5 3.0 3.3 9.5 3.2 15w0d 9.7 2.6 13.0 36w2dt3
38 30 Kanuri 5 8.8 7.4 24.6 8.7 33w1d 27.9 6.9 34.1 23w5d
39 35 Karekere 4 5.4 5.0 15.2 5.7 22w3d 17.6 4.3 21.8 3/3/08 23w5d
40 30 Kanuri 6 7.1 6.6 20.8 6.8 26w 22.0 4.6 29.9 27wks
41 31 Marghi 3 10.8 9.1 30.2 9.2 35w+3 34.3 7.3 37.0 11/1/8 36w+4d
42 38 Marghi 2 9.3 8.0 26.2 9.0 34w+5d 28.5 6.9 34.1 7/2/8 35w+6d
43 28 Kanuri 0 7.6 5.4 19.7 7.0 26w+4d 22.8 6.7 28.4 11/3/8 29w+0d
44 27 Kanuri 0 7.1 5.5 19.1 6.3 24w+3d 20.9 5.1 26.2 31/3/8 26w+5d
S/N
1
AGE
2
TRIBE
3
PARIT
Y
4
BPD
8
BPD
GA
9
AC
10
FL
11
HC
12
LMP
13
Average
GA
14
5
D1
6
D2
7
TC
45 22 Kanuri 2 6.8 6.3 19.9 6.6 25w+3 22.5 5.0 27.6 28w+2d
46 33 Kanuri 6 7.1 6.9 21.2 7.5 28w+1d 23.1 5.8 28.7 29w+4d
47 29 Shuwa 0 6.0 6.3 18.6 6.3 24w+2d 20.5 4.2 24.2 16/4/8 25w+2d
48 23 Kanuri 0 8.6 9.8 27.9 8.9 34weks 31.4 35.6 30/1/8 38weeks
102
49 28 Kanuri 2 8.9 8.4 26.2 8.2 30w+6d 31.3 7.1 37.5 14/4/8 37w+1d
50 36 Igbo 6 8.3 7.9 24.6 8.4 31w+5d 31.3 6.9 33.5 2/2/8 34w+5d
51 20 Kanuri 0 8.9 8.0 25.6 7.9 29w+5d 27.6 6.4 33.4 2/2/8 34w+4d
52 40 Marghi 6 7.0 7.4 21.8 6.7 25w+5d 22.0 4.9 26.6 27w+1d
53 27 Marghi 0 4.6 4.8 14.2 4.7 19w+2d 14.6 3.4 18.2 20w+4d
54 23 Kanuri 0 6.1 7.0 13.1 6.8 26w+0d 21.9 5.2 27.1 7/4/8 27w+5d
55 40 Kanuri 5 7.1 7.1 21.5 7.4 28weks 23.9 5.8 29.6 7/3/8 29w+6d
56 37 Chibok 2 8.1 8.3 24.9 7.7 29weks 26.7 6.2 31.3 3/8 33weeks
57 15 Fulani 0 10.4 9.5 30.2 9.1 35w+0d 33.1 7.8 36.2 35weeks
58 35 Kanuri 7 7.7 6.9 22.1 6.6 25w+2d 22.8 5.6 28.1 13/4/8 29w+3d
59 24 Fulani 4 5.4 5.3 16.2 5.7 22w+2d 18.2 3.8 22.4 22/5/8 23w+3d
60 18 Hausa 0 9.0 10.2 29.1 8.1 30w+4d 29.5 6.9 32.5 35w+5d
61 31 Kanuri 3 5.8 5.4 15.6 5.0 20w+3d 16.6 3.6 20.2 25/5/8 21w+6d
62 19 Kanuri 0 4.9 5.9 17.7 5.7 22w+3d 18.6 4.1 23.1 24w+0d
63 26 Kanuri 2 9.4 10.3 29.9 8.5 32weks 30.3 7.0 34.6 6/2/8 37w+4d
64 25 Fulani 2 4.1 4.1 12.4 3.9 17w+2d 12.7 2.8 15.7 18w+3d
65 21 Fulani 0 9.5 7.8 26.2 8.7 33w+1d 30.4 7.1 34.9 28/1/8 37w+3d
66 19 Shuwa 0 5.3 4.5 14.8 5.1 20w+4d 16.9 3.8 21.4 22w+3d
67 26 Igbo 3 5.8 5.9 17.7 6.2 24w+3d 20.1 4.7 24.1 25w+3d
68 28 Kanuri 2 6.0 5.8 17.9 6.1 23w+4d 20.2 4.9 24.7 26w+4d
69 29 Shuwa 7 9.4 7.7 25.9 7.9 29w+4d 28.7 6.7 32.1 12/2/8 34w+3d
70 20 Hausa 0 9.2 8.4 26.7 8.8 33w+3d 29.2 6.9 35.2 26/3/8 36w+3d
71 20 Chibok 1 8.1 8.5 25.2 8.3 31w+3d 26.9 6.6 32.9 15/2/8 34w+3d
72 26 Shuwa 4 8.9 8.1 25.8 9.0 34w+3d 31.6 7.0 34.7 38w+1d
73 26 Kanuri 2 8.8 9.8 28.2 8.7 33w+1d 31.6 7.4 34.8 39w+2d
74 20 Kanuri 0 5.2 5.2 15.8 4.4 18w+4d 15.9 3.5 17.8 20w+5d
75 25 Kanuri 6 2.7 2.5 7.9 3.2 15week 9.6 1.9 12.5 15w+5d
103
76 27 Hausa 3 6.0 6.0 18.2 5.8 22w+4d 19.2 4.3 23.6 24/5/8 25w+1d
77 23 Babur 0 5.1 4.8 15.0 4.5 18w+5d 16.2 3.8 18.9 21w+2d
78 20 Hausa 4 3.7 3.2 10.4 3.6 16w+3d 11.6 2.3 14.6 17w+2d
79 30 Igbo 1 9.2 8.5 26.9 7.4 28w+1d 26.1 6.0 30.3 18/3/8 31w+0d
80 22 Kanuri 2 5.0 4.4 14.2 5.0 20w+3d 16.6 3.7 20.6 22w+0d
81 20 Kanuri 0 6.4 5.5 18.0 6.3 24w+1d 19.6 4.8 25.1 25w+5d
82 23 Babur 0 9.2 8.5 26.9 9.3 35w+5d 31.8 7.1 36.2 4/3/8 37w+3d
83 36 Fulani 4 3.9 3.9 11.8 4.5 18w4d 13.3 2.8 17.5 5/7/8 19w+3d
84 16 Kanuri 1 5.8 5.3 16.8 5.7 22w+2d 20.2 4.9 23.2 25w+1d
85 25 Kanuri 0 8.0 6.7 22.3 7.0 26w+4d 24.0 5.9 28.9 30w+4d
86 18 Fulani 0 7.7 7.7 23.4 7.8 29w+2d 25.2 5.9 30.7 31w+1d
87 25 Babur 3 6.1 5.5 17.6 5.0 20w+3d 17.9 4.3 21.3 24weks
104
S/N
1
AGE
2
TRIBE
3
PARITY
4
BPD
8
BPD
GA
9
AC
10
FL
11
HC
12
LMP
13
Averag
e
GA
14
5
D1
6
D2
7
TC
88 24 Babur 0 5.0 5.3 15.6 5.3 21w+1d 16.3 3.9 20.5 17/6/8 22w+2d
89 29 Fulani 0 8.4 7.3 23.8 7.5 28w+2d 25.0 5.6 29.3 28/4/8 30w+1d
90 35 Shuwa 4 10.3 10.3 31.3 9.1 35w+1d 33.6 7.7 35.8 20/2/8 35w+1d
91 35 Igbo 5 6.0 5.8 17.9 5.7 22w+2d 19.0 4.6 23.1 24w+4d
92 35 Wuruk 5 7.7 7.2 22.6 7.3 27w+4d 25.5 5.8 29.5 30w+2d
93 25 Igbo 0 4.0 4.5 12.9 4.4 18w+3d 16.5 3.7 19.2 21w+2d
94 31 Bura 3 10.3 10.4 31.4 10.0 41w+3d 38.1 8.1 38.5 10/2/8 41w+3d
95 29 Kanuri 1 7.7 7.8 23.5 7.2 27w+2d 24.8 5.5 28.8 29w+4d
96 35 Hausa 4 4.0 4.0 12.1 4.1 17w+5d 12.4 2.9 16.3 18w+5d
97 28 Marghi 1 8.8 8.3 25.9 8.2 30w+6d 28.6 6.7 32.4 35w+0d
98 30 Kanuri 5 2.4 3.8 9.4 3.7 16weks 11.5 2.0 14.9 16wks
99 17 Bajizim 0 2.6 2.7 8.0 3.7 17w+2d 12.3 2.2 14 17w+1d
100 30 Igbo 3 2.9 3.6 9.8 3.9 18weks 12.1 2.6 14.2 17w+3d
101 30 Hausa 3 3.5 3.9 11.2 4.6 19weks 14 2.9 17 20wks
102 27 Marghi 2 4 5 13.6 5.5 21w+5d 15.9 3.7 20.4 22w+3d
103 18 Kilba 0 3.5 4 11.4 5.7 22w+3d 15.8 3.8 20.7 22w+3
104 25 Kanuri 0 4.7 5.6 14.7 6.2 24weks 17.9 4.2 23 24w+3d
105 20 Igbo 0 5.6 5.0 17.0 6.5 25w+5d 18.4 4.7 24 25w+5
106 20 Bura 0 4.6 6.2 16.4 6.8 26w+6d 17.4 4.8 25 26w+6d
107 30 Fulani 2 5.9 6.3 18.5 7.1 27weks 19.7 4.8 25.9 27w+3d
108 25 Kanuri 2 4.7 6.3 16.7 7.2 27w+3d 20.6 5.2 26.7 28w+1d
109 28 Shuwa 7 6.0 8.3 21.7 7.3 28w+0d 20.7 5.2 26.9 28w+1d
110 20 Kanuri 3 7.4 6.8 21.5 9.2 35w+5d 26.4 6.2 33.4 35w+3d
105
111 20 Kanuri 4 6.9 7.5 21.8 8.4 34w+4d 26.7 7.3 30 37wks
112 18 Hausa 0`̀ 5.0 4.8 15.3 5.3 22w+1 17.1 4.0 22wk+2
d
113 45 Hausa 10 8.8 8.1 26.5 8.8 35w+4 32.5 7.2 36w+4d
114 32 Hausa 5 7.7 7.3 23.55 8.1 32w+4 27.1 7.8 32w+2d
115 18 Hausa 0 4.3 3.8 12.7 3.9 17w+6 13.8 2.4 17w+6d
116 Hausa 1 6.5 6.1 19.7 7.4 29w+5 24.0 5.5 29w+2d
117 20 Hausa 1 7.9 7.2 23.7 7.6 30w+4 24.1 6.3
118 20 Hausa 0 7.1 6.8 22.4 7.1 28w+4 23.8 5.7 28w+6d
119 25 Hausa 3 7.5 7.4 23.3 8.2 33w+0 28.4 6.5 33w+0d
120 20 Hausa 2 7.5 8.2 24.6 8.5 34w+5 30.4 6.5 34w+1d
121 25 Hausa 4 4.4 4.7 14.2 5.0 21w+1 16.3 3.1 20w+4d
122 20 Hausa 0 5.0 4.5 14.9 5.5 22w+6 18.1 4.0 22w+5d
123 20 Hausa 1 8.8 7.1 24.9 8.6 34w+5 29.6 7.0 34w+5d
124 20 Hausa 3 7.4 7.0 22.6 7.9 31w+5 27.4 6.5 32w+1d
125 20 Hausa 2 6.2 6.3 19.6 7.3 29w+3 23.8 5.7 29w+0d
126 22 Hausa 3 5.2 4.6 15.3 4.8 20w+4 19.0 3.5 21w+5d
127 23 Hausa 1 8.2 7.6 24.8 8.2 33w+0 26.9 6.3 32w+1d
128 24 Hausa 2 5.5 4.6 15.8 5.3 22w+1 18.6 4.1 22w+6d
129 26 Hausa 0 7.9 7.2 23.7 8.2 33w+0 27.1 5.8 32w+0d
130 26 Hausa 1 8.5 7.9 30.4 8.8 35w+4 31.0 7.3 36w+0d
The raw data of 130 of 907 participants.
106
SONOGRAPHIC ASSESSMENT OF FOETAL THORACIC CIRCUMFERENCE AS A PREDICTOR OF GESTATIONAL
AGE IN MAIDUGURI, NORTH EAST NIGERIA
BY
NWOBI, CHIGOZIE IVOR PG/M.Sc/03/37246
DEPARTMENT OF MEDICAL RADIOGRAPHY AND RADIOLOGICAL SCIENCES
FACULTY OF HEALTH SCIENCES AND TECHNOLOGY COLLEGE MEDICINE
UNIVERSITY OF NIGERIA ENUGU CAMPUS
FEBRUARY, 2012.