Infectious Diseases in Pregnancy

Question 1

What are the differences between Primary, Secondary and Tertiary Prevention?

Answer 1

Primary Prevention

• behaviour
• vaccination

Secondary Prevention

• screening for subclinical infection (e.g. Asymptomatic bacteruria, GBS)
• screening to prevent mother to child transmission (HBV)

Tertiary Prevention

• Treatment of established infection (antibiotics for sepsis)

Question 2

What types of infections cause vaginal discharge? What are some non-infectious discharges?

Answer 2

Infectious:

• bacterial vaginosis
  
  • foul fishy smelling
  • greyish white to yellow-white - itching
  • ‘clue cells’
  • treat with metronidazole
• chlamydia trichomatis
  
  • PID with chlamydia - dyspareunia
  • white/grey/yellow/green - frothy, copious, homogenous
  • strawberry cervix
  • treat with tetracyclines
• candidiasis
  
  • low pH thick white
  • thick cottage cheese-like
  • precipitated by antibiotics with diabetes

Non-infectious:

• ovulation
  
  • clear discharge with stretchy quality
• show
  *

Question 3

What are some teratogenic maternal infections?

Answer 3

• TORCH (toxo, rubella, CMV, herpes, HIV)
  
  • toxoplasmosis - maternal flu-like illness, IgM/G avidity tells recentness of infection, treatment with spiramycin.
• Parvovirus
  
  • 8-20weeks
  • hydrops foetalis
• Varicella
  
  • congenital varicella rare - dermatological effect
• CMV
  
  • early = 10% risk
  • late = 60% risk
• Syphilis
• Zika

Question 4

What are some management princoples for infections in pregnancy?

Answer 4

• avoid infection
  
  • vaccines
  • screening
  • antibiotics
  • hand-washing
• diagnose with Ix (serology, tissue PCR)
  
  • screen in early pregnancy for Rubella, Syphilis, HBV, HCV, MSU
    
    • VZV not on RANZCOG
    • HSV on Hx

Question 5

What is the management of a + GBS diagnosis at 36 weeks in pregnancy?

Answer 5

• risk - transmission to fetus from vaginal delivery:
  
  • neonatal sepsis especially with PROM
    
    • pneumonia
    • meningitis
    • sepsis
• Antibiotics ideally <4 hours before delivery.
• Intrapartum antibiotics
  
  • initial loading dose
  • 4 hourly until delivery
• if baby gets infected treat all future pregnancies as GBS+

Question 6

What is the management of herpes simplex in pregnancy?

Answer 6

• can be HSV 1 or 2. (50/50).
• DDx - ensure not other viral/bacterial/anatomical variant.
• confirm diagnosis with PCR/culture from lesions

Treatment:

• symptomatic control:
  
  • analgesia, warm baths
  • acyclovir for 7-14days to reduce duration of viral shedding
• give suppressive therapy from 36 weeks.
• CS delivery if active lesions during labour.

Question 7

What is the management of a 10 week gestation women with known HIV+ status?

Answer 7

Assess HIV disease:

• CD4 count
• risk of disease progression (viral load)
• desire to continue pregnancy?

Counsel about risks:

• materno-foetal transmission (high load/low CD4 count, delivery, breastfeeding)
• no intervention 25-30%

Treatment:

• HIV treatment (controversial) - zidovudine immediately (fetal risks) vs starting at 14 weeks gestation.

Question 8

A primi 8 week gestation schoolteacher tell you one of her students has rubella. What is your management?

Answer 8

• Rubella infection risk:
  
  • symptoms (rash, ever, when exposed (incubation period), vaccinations)
  • investigations - if no rubella serology before pregnancy
    
    • IgG/IgM - weak IgG can still be infected, IgM means recent infection.
• congenital risk:
  
  • risks are higher in the 1st trimester.
    
    • cataracts
    • ear - sensorineual deafness
    • heart - PDA
    • mental retardation
    • IUGR/abortion
• offer a TOP
• give MMR, avoid pregnancy for 28 days.

Question 9

What screening of infection in pregnancy do you do?

Answer 9

• Rubella
  
  • not everyone stays completely immune (only IgG in screening).
  • MMR after pregnancy 28 days can’t get pregnant
• Syphilis
  
  • STD - still in african population, incidence low.
  • pregnancy problems:
    
    • miscarriage/Preterm, stillbirth, hepatomegaly, skin rash/lesions, ascites
  • Nontreponemal test (RPR or VDRL), treponemal test (TPPA or TPHA - what we do here)
  • treat patient/partners with penicillin, determine primary, secondary or tertiary
  • if high risk repeat at 28-32weeks.
• HIV
  
  • all women offer, don’t want it don’t push
  • serology for titre.
  • risk of vertical transmission reduced to 1% from 20% from interventions
    
    • ART,
    • no breastfeeding,
    • CS if >50copies/ml,
    • avoid ROM/fetal scalp
• Hep B
  
  • surface antigen screening if HBsAg + then go to HBeAg/HBV DNA/LFTs
  • IVIG and treat mother, and vaccine
  • chronic (DNA <10^7) don’t treat mother only baby, acute treat mother >10^7 HBV DNA load)
• Hep C
  
  • antibody status - HCAb + then do HCV RNA/LFTs
  • viral load and LFT + - try to expedite delivery (no vaccuum, cuts etc…)
  • HCV RNA -ve then past tx, cleared infection
• Varicella
  
  • not part of routine screening
  • exposure - previous history (no action), no previous/uncertain history:
    
    • check serology urgently
      
      • seropositive - no action,
      • seronegative - assess time of exposure
  • treatment for seronegative:
    
    • <96hrs ZIG VZ immunoglobulin
    • >96 hrs - consider oral acyclovir PEP if at risk
      
      • second half of pregnancy, underlying lung disease or immunocompromised.
      • 800mg 5x a day (high dose) for 7 days
    • <24 hrs from rash oral acyclovir, beyond don’t worry because beyond that point. Risk use IV.
  • fetal varicella syndrome:
    
    • risk is extremely low - eye abnormalities, skin scars, limb changes, premature, early death, mental (ID).
    • fetal abnormality scan 5 weeks after exposure.
• MSU
  
  • asymptomatic bacteruria - 40% cystitis, 30% pyelonephritis
    
    • acute pyelonephritis - right kidney usually (stasis of urine from uterus) - look for endotoxemia.
  • 10^5 or more CFU
  • management - treated to stop premature/IUGR
  • treatment (ampicillin/cephalosporins - NOT trimethoprim (extra folate, not early in pregnancy) or nitrofurantoin (late, can cause hemolytic anaemia)).
• GBS
  
  • 10-30% of women, 70% born of colonised women are colonised themselves. Early onset GBS disease (EOGBS).
  • week 36 if + give chemoprophylaxis of benz pen or previous baby with sepsis or within urine - treat as highly colonised (reduce sepsis).
    
    • screening approach
    • risk factor approach (>18hrs, premature)

Question 10

What vaccinations/steps can you give women to prevent infection?

Answer 10

• prevention during - pertussis and fluvax
• Hep B, Rubella, chicken pox after pregnancy
• handwashing (CMV/toxoplasmosis)
• avoid high risk foods (listeria/toxoplasmosis)
  
  • unpasteurized mild, pate, dips, soft cheeses, precooked seafood chilled, precooked meats, uncooked, preprepared salads

Question 11

Vertical transmission of infections, what do we look for?

Answer 11

• not detrimental to mum but are to the fetus:
  
  • STORCH
    
    • toxoplasmosis
      
      • management plan - routine screening not recommended. Heart ache. Reason!
      • IgG + IgM + - within 3 mths possible recent, look at avidity (can linger).
      • risk depends on timing:
        
        • 1st trimester 5-15% but damage higher, 2nd trimester 40% but middle, 3rd trimester high risk but less damaging
      • treatment antibiotics and fetal diagnosis
        
        • US - calcifications/hydrocephalus, amniocentesis and TOP if abnormal in both amnio/US.
    • Others (parovirus, VZV, adenovirus, Zika)
      
      • parvovirus - slapped cheek. 40% of women
      • fetal loss low, proven infection its 10% (in uterus)
      • serology - confirmed at <20 weeks - US 1-2weeks for 12 weeks.
      • fetal hydrops - fetal anaemia.
      • Easy treatment - intrauterine transfusion.
    • Rubella
    • CMV
      
      • leading cause of congenital infections 0.6-0.7. Primary 30% transmission, non-primary approx 1%.
      • antenatal testing complex. Don’t do it early.
        
        • serology - IgG +/IgM+ -avidity test (long time for residual IgM), low its recent.
      • no treatment so don’t screen!
        
        • do amniocentesis 6 weeks post infection or past 21 weeks gestation (don’t excrete before 21).
        • US/MRI
      • congenital CMV - microcephaly neurological/sensorineural/death/ascites/hydrops/IUGR/calcifications.
    • HSV
      
      • acyclovir during pregnancy
      • 36 weeks onwards prophylactic acyclovir
    • syphilis

Question 12

Infection and premature delivery?

Answer 12

• intraamniotic infection (GBS, ureplasma/myoplasma/E. coli)
• systemic infection (flu/sepsis)
• extra-uterine maternal infections (pyelonephritis/pneumonia)