ULTRASOUND IN ULTRASOUND IN

OBSTETRICS & GYNECOLOGYOBSTETRICS & GYNECOLOGY

Hidayat Wijayanegara

Department of Obstetric & Gynecology School Medicine Padjadjaran University /

Hasan Sadikin Hospital Bandung

Ultrasound examination : Reveals vital information Fetal anatomy Fetal environment Growth Well being

No biological hazard

The first obstetrical application of USG

imaging : Ian Donald (1958)

Sound waves of frequencies higher than

the hearing limit of the human ear are

called ultrasonic waves

The limit is by convention 20 KHz

Medical practice frequencies between

1-10 MHz are commonly used

Ultrasound

Technology :

Sound waves reflecting back from Sound waves reflecting back from

the fetus or image structure the fetus or image structure

displayed on the ultrasound screendisplayed on the ultrasound screen

Alternating current is applied to a Alternating current is applied to a

transducer made of piezoelectric transducer made of piezoelectric

material material intermittent high intermittent high

frequency sound waves exceeding frequency sound waves exceeding

20,000 cps are generated 20,000 cps are generated

The transducer emits a pulse of sound waves The transducer emits a pulse of sound waves that passes through the layer of soft tissuethat passes through the layer of soft tissue

Interface between structures of Interface between structures of

different tissue densities different tissue densities

Some of the energy is reflected back Some of the energy is reflected back to the transducer to the transducer

A small electrical voltage A small electrical voltage

Display on a screen Display on a screen

Bone is dense (echogenic) Bone is dense (echogenic) white on the white on the screenscreen

Fluid (anechoic) Fluid (anechoic) black black Soft tissues Soft tissues varying shade of gray varying shade of gray

1.Operator control1.Operator control 6. Visual 6. Visual informationinformation

2.Transducer drive2.Transducer drive 5. Electric 5. Electric informationinformation

3.Ultrasound pulses 3.Ultrasound pulses 4. Acoustic 4. Acoustic informationinformation

The diagnostic ultrasound visualization The diagnostic ultrasound visualization methodmethod

OperatorOperator

InstrumentInstrument

TransducerTransducer

Tissue interactionTissue interaction

TransabdominalTransabdominal Scanning : Scanning :

Performed with 3.5 – 7 MHzPerformed with 3.5 – 7 MHz

Safety : no confirmed biological Safety : no confirmed biological

effects in mammalian tissue have effects in mammalian tissue have

been demonstrated in the been demonstrated in the

frequency range of medical frequency range of medical

ultrasound (AIUM, 1991)ultrasound (AIUM, 1991)

Choice of equipment :

Transabdominal scanningTransabdominal scanning

Transvaginal scanningTransvaginal scanning

Doppler and color flow imagingDoppler and color flow imaging

3D3D

2D

Biophysical mechanism :

Are not fully understood

The effects of ultrasound on various biological entities may be due to one or a combination of any of the following :

1. Heating effects

2. Cavitational effects

3. Mechanical effects

Are associated only with high Are associated only with high average intensities and not average intensities and not found in diagnostic equipmentfound in diagnostic equipment

Preparation of the patient

Ultrasound beam cannot penetrate gasUltrasound beam cannot penetrate gas The interface created by gas The interface created by gas the sound the sound

beam totally reflectedbeam totally reflected Water Water excellent transmission medium excellent transmission medium The distension of bladder The distension of bladder displaces displaces

intestinal loop intestinal loop acoustic windowacoustic window to the to the pelvic structure pelvic structure

Patient should be scanned with a full Patient should be scanned with a full bladder bladder

The full bladder technique offer :The full bladder technique offer :

1. It displaces the fetal head upwards1. It displaces the fetal head upwards

2. It allow visualization of the cervix2. It allow visualization of the cervix

Coupling agents

A gel or an oil A gel or an oil eliminates the air eliminates the air interface between the transducer interface between the transducer and the patient’s skinand the patient’s skin

Scanning technique The patient is on your rightThe patient is on your right The machine is on your leftThe machine is on your left Work in dim lighting to help Work in dim lighting to help

reflection on the screen reflection on the screen

Indications for ultrasound examination

Gynecology : - Uterus, Ovaries, AdnexaGynecology : - Uterus, Ovaries, Adnexa

- - Abnormal bleeding, pelvic pain & Abnormal bleeding, pelvic pain & discomfortdiscomfort

- IUCD location and complications- IUCD location and complications

- Pelvic mass reveals mass or - Pelvic mass reveals mass or enlargement of pelvic organ enlargement of pelvic organ

- Evaluation of masses palpable - Evaluation of masses palpable

- Ovulation induction therapy - Ovulation induction therapy

- Guidance for abscess drainage- Guidance for abscess drainage

Uses of ultrasound in gynecology

1. Determine the size and location of lesions2. Characteristics of the lesion: cystic, complex

or solid3. Determine if mass is uterine or extrauterine4. Evaluate the extent of pelvic inflammatory

disease or endometriosis and follow-up5. Follow the course of a simple cyst: regression,

etc.6. Locate the position of an intrauterine device7. Detection of ascites8. Radiation therapy planning

Obstetrics :

Routine obstetrical ultrasound scan: 18-20 weeks

1st Trimester : Confirm pregnancy, viability, gestational age Rule out :

Ectopic pregnancyGestational trophoblastic diseaseForeign bodies

Large for dates – fibroid, uterine malformation, multiple gestation

Small for dates – missed abortion, blighted ova

Ovaries, rule out adnexal lesions, uterine position, rule out uterine anomalies

Undetermined etiology of vaginal bleeding

Suspected complications, i.e subchorionic hematome

22ndnd and 3 and 3rdrd trimester : trimester :

Confirm viability, gestational age, fetal number

Evaluated fetal growth, anatomy, lie, position, follow up anomaly

Evaluate placenta, AFV, cord

Biophysical profile for fetal well being

Vaginal bleeding

Components of basic ultrasound examination according to Trimester pregnancy

1st trimester Gestational sac

location

Embryo identification

Crown rump length (CRL)

Fetal heart rate motion

Fetal number

Uterus & adnexal evaluation

2nd and 3rd trimester

Fetal number Presentation Fetal heart motion Placental location Amniotic fluid volume Gestational age Survey of fetal

anatomy Evaluation for

maternal pelvic mass

Ultrasonic Landmark Occurence

(weeks of gestation)

Gestational sac 5 – 6 weeks

Fetal embryonic pale 6 – 7 weeks

Detection of fetal life 7 – 8 weeks

Placenta 8 – 10 weeks

Loss of gestational sac 11 – 13 weeks

Fetal head 11 – 14 weeks

(Biparietal diameter)

Evaluation of ultrasound to determine gestational age

Crown Rump Length (CRL)

Biparietal diameter (BPD)

Femur Length (FL)

Head Circumference (HC)

Abdominal Circumference (AC)

Accuracy of ultrasound measurement for different gestational groups

Ultrasound parameter Accuracy

Gestational sac diameter + 7 days Crown Rump Length + 3-5 days BPD second trimester + 1 to 1.5

weeks BPD third trimester + 2 to 4

weeks FL second trimester + 1 to 1.5

weeks FL third trimester + 3 to 3.5

weeks Multiple parameter (2nd trimester) + 1.5

weeks Multiple parameter (3rd trimester) + 2.5

weeks

Summary

1. Physics of ultrasound

The ultrasound used in clinical practice is limited to frequencies in the range of 1-10 cycles per second (1-10 MHz)

In Obstetrics : 3.5 MHz and 5 MHz

2.UltrasoundIs produced when transmitted pulses of sound from the transducer cross body structures and reflect energy back to the transducer from the interfaces of organs

3. Ultrasound in Obstetrics Confirmation of an intrauterine

pregnancies

Exclusion of an ectopic pregnancies

Assessment of an intrauterine pregnancies

Determination of gestational age :

Are uncertain of the date of conception

Resolving discrepancies between gestational age and uterine size :

Large for dates

Small for dates

Investigation of uterine bleeding Visualization for high risk procedures

Amniocentesis Chorionic villous sampling Cordocentesis

Evaluation of fetal well-being Distinguish congenital malformation Biophysical profile

Doppler flow velocimetry IUGR 60-80% of the time in cases where the

umbilical artery waveforms are abnormal due to uteroplacental insufficiency