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MID TRIMESTER ASSESSMENT VIRAL INFECTIONS

MID TRIMESTER ASSESSMENT VIRAL INFECTIONS. NORMAN BLUMENTHAL FRANZCOG BLACKTOWN HOSPITAL. Question 1 . What percentage of pregnancies are complicated by serious (major) birth defects?. Serious Birth Defects. complicate & threaten the lives of 3-5% of newborn infants

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MID TRIMESTER ASSESSMENT VIRAL INFECTIONS

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  1. MID TRIMESTER ASSESSMENT VIRAL INFECTIONS NORMAN BLUMENTHAL FRANZCOG BLACKTOWN HOSPITAL

  2. Question 1 • What percentage of pregnancies are complicated by serious (major) birth defects?

  3. Serious 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

  4. Ultimate aims of prenatal diagnosis • 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

  5. Aims 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

  6. Question 2 • What is the best available serum screening test for neural tube defects and when it is done?

  7. Spina Bifida • Increased AFP (> 2.5 MoM) • correlates with open skin defects

  8. Increased risk of a fetus 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

  9. Current recommendations for 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

  10. The 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

  11. The 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

  12. The 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

  13. The Triple Screen Disdvantages: • detection rate approximately 65%

  14. Does screening do more harm than good? • Screening raises parents expectations of medicine, and their expectations of a perfect baby • False positives cause anxiety and occasional miscarriages of normal fetuses • False negatives leave parents with an unwanted Down syndrome child to bring up. They often feel misled, betrayed by their “statistics-quoting doctor”, and quite litigious • Some patients become unreassurable, and have an unnecessary procedure

  15. Congenital 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

  16. Normal 4 chamber view

  17. TRV Fetal HandPolydactyly Fetal LegFracture in Osteogenesis Imperfecta Fetal Feet: Bilateral Club Foot TRV Fetal AbdomenDuodenal Atresia (Double-Bubble sign)

  18. Question 3 • The 18-week morphology scan is good and accurate in the assessment of Downs Syndrome (T/F)?

  19. 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 Ultrasonic features of Trisomy 21 at the 18 week anomaly scan

  20. Comparison of screening parameters at 18 week anomaly 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

  21. Accuracy of Midtrimester US screening for detectable 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

  22. INFECTIONS IN PREGNANCY

  23. Infections pose a problem for • mother • baby • both Some infections • antepartum • intrapartum • postpartum

  24. VIRUSES

  25. Question 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.

  26. Herpes 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

  27. 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

  28. Treatment • Antiviral e.g. Acyclovir/famcyclovir • Caesarean if lesions present • Recurrent attacks now debatable

  29. CMV • 50% of Austr. population immune(IgG pos) • 2% of births • Acquired by primary or recurrent infections • Primary infection occurs in 4% of pregn

  30. Maternal Infection • Asymptomatic • Mononucleosis like symptoms • fever, fatigue, myalgia, pharyngitis, diarrhoea, lymphadenopathy. • Diagnosed by culture or antibody detection

  31. Foetal • Transplacental transmission • Primary infection • 40% risk of infection • 10% symptomatic atbirth • 10% symptomatic later • Suspicion based on U/S • IUGR, micro/hydrocephaly, periventricular • calcifications, ascites, effusions, oligo/polyhydramnios

  32. Recurrent 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

  33. Varicella 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

  34. Congenital malformations • Highest risk of foetal damage 13-20 weeks • Skin scarring in dermatomal distribution • Limb hypoplasia • Eye defects - micropthalmia, cataracts • Neurological abnormalities

  35. Noenatal 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

  36. Toxoplasmosis • Protozoan parasite • Cat host - passed in cat faeces but mustmature in soil prior to becoming infective • Undercooked meat, soil, animal contact • Prevalence varies - France, S. America 80% Australia 30-40% sero +ve

  37. Congenital 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

  38. Diagnosis • Difficult - maternal infection asymptomatic • Demonstrate seroconversion • Amniocentesis or foetal blood sample

  39. Management • Serial IgG and IgM • If seroconversion - monitor foetus by serial ultrasound - hydrops foetalis, IUGR

  40. Question 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.

  41. Rubella • 90% women immune • Vaccine live - give postpartum • Congenital Rubella Syndrome - before 16 weeks - cataracts, glaucoma, deafness, cardiac - after 16 weeks

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