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?

Spina BifidaSpina Bifida

Increased AFP (> 2.5 MoM) correlates with open skin defects

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

The Triple ScreenThe Triple Screen

Disdvantages: detection rate approximately 65%

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

Normal 4 chamber view

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

Placenta praevia

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 IN PREGNANCYINFECTIONS IN PREGNANCY

Infections pose a problem forInfections pose a problem for

– mother

– baby

– both

Some infections

– antepartum

– intrapartum

– postpartum

VIRUSESVIRUSES

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.

RubellaRubella

90% women immune Vaccine live - give postpartum Congenital Rubella Syndrome

- before 16 weeks

- cataracts, glaucoma, deafness, cardiac

- after 16 weeks