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NORMAN BLUMENTHAL
FRANZCOG
BLACKTOWN HOSPITAL
MID TRIMESTER ASSESSMENT MID TRIMESTER ASSESSMENT
VIRAL INFECTIONS VIRAL INFECTIONS
Question 1Question 1
What percentage of pregnancies are complicated by serious (major) birth defects?
Serious Birth DefectsSerious Birth Defects
complicate & threaten the lives of 3-5% of newborn infants
account for 20% of neonatal deaths account for 30% of serious morbidity
in infancy and childhood
Ultimate aims of prenatal Ultimate aims of prenatal diagnosisdiagnosis
provide accurate diagnoses and informative prognoses to the mother and her family
with a low or no risk of miscarriage as early as possible in the pregnancy to allow informed decisions about the
pregnancy
Aims of prenatal diagnosisAims of prenatal diagnosis
To provide the options of pregnancy termination in-utero treatment arrangements for the best method of delivery
and optimal peri-natal care
Question 2Question 2
What is the best available serum screening test for neural tube defects and when it is done?
Increased risk of a fetus Increased risk of a fetus with a NTD with a NTD
Family history of NTD in mother’s or father’s close relatives
Pregnant women with IDDM Pregnant women on anti-convulsant
medication
Current recommendations for Current recommendations for Folate (folic acid) Folate (folic acid)
Daily folate intake of 5mg for all women who may become pregnant( 1 mth before)
Tablets available over the counter– $2.50-$5.20 for 90 tablets
Dietary folate– 2 servings of orange, banana, strawberries– 5 servings of asparagus, beans, beetroot, brussel sprouts, broccoli,
cabbage, cauliflower, leeks, parsnips, peas, potato, spinach – 7 servings of wheat germ, wheat bran, wholegrain bread, pasta,
cereals
The Triple ScreenThe Triple Screen
Analytes: estriol, AFP, beta-HCG Serum collected at 15-17 weeks gestation Assayed in centralised laboratories Risk of Down syndrome assessed by collating
serum results with patient’s age and previous history If risk >1:250 at term - recommend amniocentesis
The Triple ScreenThe Triple Screen
Advantages: Little skill required to collect blood Assayed in centralised laboratories
- good QA performed at 15-17 weeks gestation
– subsequent karyotyping by amniocentesis
The Triple ScreenThe Triple Screen
Disdvantages: Requires pre-test and post-test counselling Results highly dependent on gestational age
– thus need a dating ultrasound beforehand Not reliable in twin pregnancies Opportunities for karyotyping only at 16 wk
– thus if TOP required - cervagem IOL Not as enjoyable for the patient as NTS
Does screening do more harm than good?Does screening do more harm than good?
– Screening raises parents Screening raises parents expectations expectations of of medicine, and their expectations of a medicine, and their expectations of a
perfect babyperfect baby
– False positives cause False positives cause anxietyanxiety and occasional and occasional miscarriagesmiscarriages of normal fetuses of normal fetuses
– False negatives leave parents with an False negatives leave parents with an unwanted unwanted Down syndromeDown syndrome child to bring up. child to bring up.
They often feel misled, betrayed by their They often feel misled, betrayed by their ““statistics-quoting doctor”, and quite statistics-quoting doctor”, and quite litigiouslitigious
– Some patients become unreassurable, and Some patients become unreassurable, and have have an unnecessary procedurean unnecessary procedure
Congenital defects: types and frequencyCongenital defects: types and frequency
Type % of births % all birth defects Structural Malformations 3.0% 60%
Monogenic defects 1.4% 28%
Chromosomal disorders 0.6% 12% Total 5.0% 100%
Ref: Prenat Neonat Med 1999;4:157-164
Fetal LegFetal LegFracture in Osteogenesis ImperfectaFracture in Osteogenesis Imperfecta
TRV Fetal HandTRV Fetal HandPolydactylyPolydactyly
TRV Fetal AbdomenTRV Fetal AbdomenDuodenal Atresia (Double-Duodenal Atresia (Double-
Bubble sign)Bubble sign)
Fetal Feet: Fetal Feet: Bilateral Club FootBilateral Club Foot
Question 3Question 3
The 18-week morphology scan is good and accurate in the assessment of Downs Syndrome (T/F)?
Ultrasonic features of Ultrasonic features of Trisomy 21Trisomy 21 at the at the 18 week anomaly scan18 week anomaly scan
thickened nuchal fold >6mm
short femurs: actual:expected FL <0.91
short humeri renal pelvic dilatation ventriculomegaly sandal gap toe
single umbilical artery widened pelvic angle echogenic bowel hypoplasia/clinodactyly of
middle phalanx of 5th finger
presence of a simian crease
echogenic focus LV
Comparison of screening parameters at 18 week Comparison of screening parameters at 18 week anomaly scananomaly scan
Ultrasound screening for aneuploidy is not a useful primary tool in the diagnosis of Down syndrome in the second trimester
Because– the findings are subtle– they require much expertise and time for
detection
Ref: D’Alton ME, Craigo S, Bianchi D. Prenatal diagnosis. Curr Probl Obstet Gynecol Fertil 1994;17(2):41-80
Accuracy of Midtrimester US screening for Accuracy of Midtrimester US screening for detectable major fetal malformationsdetectable major fetal malformations
Tertiary Non-tertiary Routine scans <24 wk 2679 (36%) 4648 (64%)Abn. fetuses detected 19/54 (35%) 8/64 (13%)Anomalies detected
CNS 67% 40%GU 50% 35%Craniofacial 50% 0%Cardiac 18% 0%GI 50% 0%Skeletal 25% 0%
Ref: Crane JP, LeFevre ML, Winborn RC et al A randomized trial of prenatal ultrrasonographic screening: impact on the detection, management and outcome of anomalous fetuses. Am J Obstet Gynecol 1994;171:392-399
Infections pose a problem forInfections pose a problem for
– mother
– baby
– both
Some infections
– antepartum
– intrapartum
– postpartum
Question 4Question 4
Genital Herpes: a. Herpes is more likely to result in
transmission of the virus to the neonate if it is recurrent as opposed to a primary attack.
b. Obvious herpetic lesions on the vulva in labour, is an indication for Caesarean section.
Herpes SimplexHerpes Simplex
Recurrent painful genital ulcers HSV 1 & 2 Transmitted to infant at time of delivery More common in primary infection(50%) < 5% with recurrent episodes
Neonatal Herpes - acquired perinatally – 95% of cases – localised - eyes, skin, mouth, CNS– disseminated - increased mortality
Congenital Herpes - acquired transplacentally– 5% of all cases– skin vesicles, chorioretinits– micro/hydrocephaly, micropthalmia
TreatmentTreatment
Antiviral e.g. Acyclovir/famcyclovir Caesarean if lesions present Recurrent attacks now debatable
CMVCMV
50% of Austr. population immune(IgG pos)• 2% of births
• Acquired by primary or recurrent infections
• Primary infection occurs in 4% of pregn
Maternal InfectionMaternal Infection
Asymptomatic Mononucleosis like symptoms
– fever, fatigue, myalgia, pharyngitis,
diarrhoea, lymphadenopathy.
Diagnosed by culture or antibody detection
FoetalFoetal
Transplacental transmission Primary infection
– 40% risk of infection
– 10% symptomatic at birth
– 10% symptomatic later
Suspicion based on U/S– IUGR, micro/hydrocephaly, periventricular
– calcifications, ascites, effusions, oligo/polyhydramnios
Recurrent InfectionRecurrent Infection
Less insiduous to neonate
- usually asymptomatic at birth
-10% hearing loss in future
Diagnosis
- 4 x rise in antibody titre IgG, IgM
Foetus
- amniotic fluid PCR
- umbilical cord sampling
Varicella ZosterVaricella Zoster
Maternal infection– may cause severe, possibly fatal chickenpox
– of all adult chickenpox - 2% in pregnancy
– 25% of all chickenpox deaths
– more severe - encephalitis, myocarditis, pneumonitis
Prevention– zoster immune globulin in 72 hrs
– acyclovir if not given ZIG
Congenital malformationsCongenital malformations
Highest risk of foetal damage 13-20 weeks Skin scarring in dermatomal distribution Limb hypoplasia Eye defects - micropthalmia, cataracts Neurological abnormalities
Noenatal ChickenpoxNoenatal Chickenpox
Occurring within 7 days prior to delivery Transplacental transmission if large amount
of virus with no maternal protective antibodies yet present
30% infant mortality Give ZIG to neonate within 72h of birth
ToxoplasmosisToxoplasmosis
Protozoan parasite Cat host - passed in cat faeces but must mature in soil
prior to becoming infective
Undercooked meat, soil, animal contact Prevalence varies -
France, S. America 80%
Australia 30-40% sero +ve
Congenital InfectionCongenital Infection Follows primary maternal infection Chances of transmission
1st trimester - 25%
2nd trimester - 54%
3rd trimester - 65% Magnitude of foetal damage greatest in
early pregnancy - Neurological abnormalities, chorioretinitus,
jaundice, rash
DiagnosisDiagnosis
Difficult - maternal infection asymptomatic Demonstrate seroconversion Amniocentesis or foetal blood sample
ManagementManagement
Serial IgG and IgM If seroconversion
- monitor foetus by serial ultrasound
- hydrops foetalis, IUGR
Question 5Question 5
Which of the following statements regarding Rubella and pregnancy are correct?
a. Congenital Rubella Syndrome may occur in patients who are known to be immune to Rubella.
b. Rubella infection after 16 weeks of pregnancy results in foetal damage in about 30% of cases.