Viral infections in pregnancy

Question 1

3 main transmission methods

Answer 1

1. In utero (aka congenital) across placenta -> Deformity, still birth worries
2. Peri-natal (vaginal secretions / blood in birth canal) -> Severe infection worries
3. Post-natal (breast milk) -> Severe infection worries

Question 2

Congenital cardiac problems (PDA)
Cataracts
Sensorineural deafness
Microopthalmia

Answer 2

Rubella
RNA virus of Togiviridae family that is directly teratogenic. Transmitted vertically. Exact manifestations depend upon when transmission occurs (worse <12w, gets better later on)
Used to be screened for at booking but now most women are positive for rubella IgG due to MMR (? women moving from abroad)
Viral PCR most accurate way of checking for infection, but can check serology for Rubella IgG / IgM

Question 3

Congenital Rubella

Answer 3

<12w 90% will get CRS as this is when organogenesis is taking place + 20% will die
12-20w slightly less risky - deafness + retinopathy main problems as this is when CNS is developing
>20 low risk - just growing at this stage

(If <12w consider counselling for termination)

Question 4

Most common congenital viral infection
Primary infection most risky
CNS involvement + hearing loss

Answer 4

CMV - Beta Herpes virus - not directly teratogenic but damages cells
Most commonly affects CSF and hearing in baby.
Primary maternal infection is more risky than re-activation or re-infection. An infected mum will typically have hepatitis symptoms (jaundice, hepatomegaly)
PCR is the best way of detecting - can test amniotic fluid at 21w pre-natally or body fluids of baby post-natally

Question 5

Vesicular skin lesions in baby

Occasionally disseminates to CNS (late seizures, lethargy), pneumonia, hepatitis

Answer 5

HSV
Mostly transmitted at delivery - 3rd trimester is most risky
CNS disease presents quite late if it does appear - classically most cases are just cutaneous symptoms on skin, eyes, mouth

Question 6

When is VZV infection most worrying?

Answer 6

Early on - congenital varicella syndrome is the worry ((low birth weight, cutaneous scarring, limb hypoplasia, chorioretinitis, cataracts) - this is pt. risky at 13-20w. This is obviously in utero transmission

Later on - worry is varicella neonatal infection (varies from a few mild skin lesions to dissemination causing pneumonia). The fetus is most at risk 7d pre-delivery to 7d post-delivery

Question 7

VZV in pregnancy

Answer 7

Live virus vaccine cannot be given in pregnancy - recommend pre-conception if trying for a baby if not previously infected
Avoid exposure to VZV
If exposed - check for VZV IgG in booking bloods or Ig in current blood test - if <10d of exposure give VZV Ig. If >10d give acylovir

Question 8

Koplik’s spots
Rash starting behind ears and forehead then spreads
Can -> opportunistic bacterial infection (otitis media)

Answer 8

Measles
RNA parmyxovirus
Main risk is to mother rather than fetus

Question 9

Slapped cheek syndrome

Aplastic crisis

Answer 9

Parvovirus B19 (Erythema infectiosum)
DNA Parvoviridae virus

Main concern is maternal infection in <20w
Risk of fetal hydrops - if infant survives hydrops survival is good

Question 10

Recommended pregnant women are vaccinated
5x increased risk of stillbirth / 3x increased risk of pre-term
No congenital abnormalities

Answer 10

Influenza