Infectious Dx in Pregnancy

Question 1

Describe the preventative measures offered by antenatal screening

Answer 1

Antenatal Screening

• Vac: influenza, pertussis
• Screen: Hep B, HIV, Rubella, Syphilis, Chlamydia, GBS etc.
• Hand hygiene: when gardening, food handling, pets, bathroom, diapers/children
• Dietary advice: listeria (soft cheeses, prepared salads, sandwich meats), toxo (undercooked chicken, kitty liter), salmonella (raw eggs)
• Avoid contact: chickenpox, rubella (rashes)
• Travel risks: Zika, malaria

Primary Prevention = beh modification to prevent infection, vaccination

Secondary prevention =

• screening for subclinical infection (asymptomatic bacteriuria, GBS)
• screen to prevent mother-fetal transmission (HBV)

Tertiary prevention = tx est infections (Abx for sepsis)

Question 2

Understand the impact of maternal infection on the infant

Answer 2

Short-term
- IUGR, miscarriage, FDIU, preterm labour

Long-term

• fetal abnormalities
• chronic: cont neuro deficits (Syphilis)
• carriage: Hep B/C –> HCC; HIV –> AIDS

Question 3

Describe differential diagnoses and appropriate tests to diagnose infection

Answer 3

♣ Antenatal Screening for:

• Hepatitis B virus [HBV]: HBsAg, HBeAg, HBcAg
• HIV: viral RNA, CD4 count
• Rubella: rise in IgG titres, IgM
• Syphilis [Treponema pallidum]
• Chlamydia trachomatis (adolescent/young mothers): urine, bloods
• Group B streptococcus [GBS]: vaginal & anal swab 36w
• Asymptomatic bacteriuria - MSU
• Varicella Zoster Virus (VZV) - VZV Ig
• Hepatitis C Virus [HCV]

♣ Not usually screened:

• CMV: PCR, fluorescence Ab’s, amnio for dx
• Toxo: IgG, IgM avidity
• Parvovirus: test IgG/M if carrier exposure
• HSV: lesions (esp if primary infection or around term)

Ix:

• Seroconversion: IgG, IgM, Avidity of Ab’s
• PCR amniotic fluid for DNA (e.g. CMV) - fetal infect
• Amnio, CVS, fetal blood sampling (fetal infection)
• Serology - HBeAg, HBcAg etc.

Question 4

Describe the principles of management of infections in pregnancy

Answer 4

• referral to high risk / perinatal unit
• Abx: GBS, Listeria, asyx bacteriuria, Syphilis
• CMV = no tx, see counselling around congenital fetal risks, ToP
• Vac & IgG: e.g. Hep B
• elective CS: HIV (reduce vertical trans)
• Rubella: live vax so pre-conception 3m, or post-partum