Rubella in pregnancy

Question 1

Incidence

Answer 1

• 1/10 000
• 25 of Australian women are non immune

Question 2

Transmission

Answer 2

Direct contact or droplet spread

Question 3

Clinical features of infection

Answer 3

• Children: maculopapular rash
• Adults: URTI, rash, fever, polyarthralgia, lymphadenopathy, conjunctivitis, pharyngitis

Question 4

Diagnosis

Answer 4

• Routine rubella serology at booking – postpartum immunisation if non-immune
• Testing of non-immune women due to contact with rubella or rubella-like illness
• Rubella serology
  o IgG seroconversion or rise in titre with positive IgM is diagnostic
  o Testing should always be repeated to confirm

Question 5

Pregnancy Implications

Answer 5

• Risk of fetal infection: Occurs during maternal viraemia
  o High <12/40 and >32/40
• <12w: >90% fetal infection
• 12-16w: 55% fetal infection
• > 16w: 45% fetal infection
• Risk of congenital defects
  o 85% <12/40: Microcephaly, severe developmental delay, sensorineural deafness, blindness and cataracts
  12-16w: 20% congenital infections with ongoing risk of sensorineural deafness with infection up to 20w
  o Fetal effects negligible with infections >16/40 (Except deafness)
• Reinfection during pregnancy: Risk of fetal infection <10% and fetal injury <5%
• Diagnosing fetal infection
  o CVS/amniocentesis for rubella PCR/culture
  o Perform >6/52 after known maternal infection (ideally >20/40)
  o Risk of false positive due to contamination with maternal tissue
• Congenital rubella syndrome
  o Sensorineural deafness 75%
  o Retinopathy/cataracts/glaucoma 25%
  o Congenital heart defects 20%: PS, TOF, VSD
  o Neurological symptoms 20%
  o FDIU/IUGR/preterm birth
  o Insulin-dependent diabetes mellitus, thyroid disease (late onset)
  Ambiguous genitalia
  HSM, jaundice, TTP, anaemia, rash

Many infants have late manifestations: Endocrinopathies, late onset deafness, ocular defects and neurodevelopmental problems

Question 6

Management

Answer 6

• Women with proven first trimester exposure should be offered a termination
  If infection 12-16w: with Invasive testing positive infection can be assumed and risk of fetal affectation dependant on GA ( 20 % risk of congenital rubella syndrome at this gestation)
  Options:
• TOP
• US surveillance to ID features with echo and 2 weekly growth US
• NB: many features may not be detectabe on ultrasound
• Management at birth
  o Ensure birth attendants are immunised/immune
  o Test infant serology, PCR of nose and throat swab and culture of urine, throat swabs, tears
  o If IgM and PCR +ve, fetus infected
• No specific management
• Ophthalmology, cardiac and hearing assessments at birth and regularly throughout life
• Infants are infectious for 12 months
  o If IgM and PCR –ve can reassure
• Repeat serology at 9 months of age to confirm IgG falling/absent