With widespread immunization against rubella, the incidence of fetal exposure to rubella has drastically decreased. Rubella causes a self-limiting infection in susceptible children and adults, but its effects on the fetus can be devastating. Risk of fetal transmission of rubella is highest if the mother develops infection within first 12 weeks of gestation and decreases in the second trimester and rate increases again in the last 10 weeks of gestation with 100% transmission 36 weeks and beyond. Early gestation infection results in multiple organ anomalies. Abnormalities are negligible when fetal infection occurs beyond 20th week of gestation.

Clinically, congenital rubella is classically characterized by cataracts, sensorineural hearing loss and congenital heart disease- predominantly a patent ductus arteriosus (PDA) or pulmonary stenosis. Our patient predominantly presented with a PDA. Other features include intrauterine growth retardation, microphthalmia, hepatosplenomegaly, retinopathy, meningo-encephalitis, thrombocytopenia, bone lucencies and diabetes mellitus. Rare manifestations include glaucoma, microcephaly, hepatitis, anemia, hypogammaglobulinemia, thymic hypoplasia, thyroid abnormalities, polycystic kidney disease and mental retardation. Onset of some of the abnormalities of congenital rubella may be delayed by months to years.

When to suspect maternal rubella infection ?
If the pregnant woman has classical rubella rash with or without arthralgia, one needs to do serum Rubella IgG titers. If positive within 7 days of exposure it suggests that the mother is immune and fetus is not considered at risk of infection. If maternal serum IgG is negative, serum IgM for rubella and repeat serum IgG after 3 to 4 weeks to look for fourfold rise in IgG levels is advised. To determine if fetal infection has occurred in such a situation, one may determine specific Rubella IgM in fetal blood obtained by percutaneous umbilical blood sampling. Direct detection of rubella antigen and Rubella RNA PCR by chorionic villus biopsy can be tried.

Postnatal diagnosis of congenital rubella: As per CDC guidelines the diagnosis of congenital rubella is made by one of the following: -

	Isolation of rubella virus from oropharynx or urine.
	Detection of rubella specific IgM in cord or neonatal blood.
	Persistent rubella IgG titers over time i.e., there is no decline in titer as expected for transplacentally derived maternal IgG. In addition, if there are congenital defects, the diagnosis of congenital rubella is made.

Treatment

There is no specific treatment for congenital rubella. Primary immunization of all susceptible persons is the best mode of prevention of congenital rubella. Conception should be avoided for 3 months following immunization, as there is a theoretical risk of fetal infection.