1999-07-24-18 Fetal rubella syndrome © Silva www.thefetus.net/
Fetal rubella syndrome
Updated 01/18/2006 by Juliana Leite, MD
Original text 05/27/1999 Philippe Jeanty, MD, PhD & Sandra R Silva, MD
Synonym: Fetal rubella effects.
Definition: Fetal rubella syndrome is a congenital disorder resulting from primary maternal infection with the rubella virus. It is characterized mainly by deafness, mental retardation, congenital cataract, heart defects, and other structural anomalies that may be found with variable severity and frequency. During acute rubella in pregnancy, the rate of congenital infection is over 90% in the 12 first weeks of pregnancy, approximately 60% in weeks 13 to 17, 25% in weeks 18 to 24 and then increases again during the last month of pregnancy.
Etiology: It is caused by a RNA togavirus, which is the only member of the genus Rubivirus. The fetus is infected by transplacental transmission.
Recurrence risk: None.
Incidence: Not precisely known. Administration of rubella vaccine has significantly reduced the incidence of maternal infection, although reinfection after vaccination is possible. The development of fetal infection reaches 50% among those exposed during the first trimester and 20% during the second trimester.
Diagnosis: The most frequent sonographic findings are cardiac malformations (in particular, septal defects), eye defects (cataracts, microphthalmia, and retinopathy), microcephaly, hepatomegaly, splenomegaly and growth restriction. Deafness and mental retardation are expected after birth. The confirmation of fetal infection can be made by isolating rubella viral RNA from amniotic fluid samples and applying polymerase chain reaction (PCR).
Associated anomalies: Occasionally the following anomalies can be associated with the classic findings of fetal rubella syndrome: renal disorders, hypospadias, cryptorchidism, meningocele, glaucoma, patent ductus arteriosus, and peripheral pulmonary stenosis.
Differential diagnosis: All the conditions that can be associated with congenital hepatomegaly and/or cataract should be excluded. It includes congenital infections (TORCHS), fetal anemia, fetal liver tumor, chondrodysplasia punctata, Neu-Laxova syndrome, Smith-Lemli-Opitz syndrome, and Walker-Warburg syndrome.
Prognosis: Intrauterine death may occur. Postnatal impact of the intrauterine infection varies from absence of any defect to all the anomalies mentioned above with variable severity. The agent may remain for years in the tissues, causing chronic infection and its complications (such as diabetes mellitus due to chronic viropathy of the pancreas).
Management: Termination of pregnancy should be considered every time fetal infection is detected during the first trimester, due to the severity of the condition in this group. After viability, monthly sonographic monitoring for growth and follow-up of the anomalies is recommended.
Prevention: Women found to be susceptible during pregnancy should be offered vaccination postpartum and before discharge from the hospital. Breastfeeding is not a contraindication to receiving the rubella vaccine.
1: Tang JW, Aarons E, Hesketh LM et al. Prenatal diagnosis of congenital rubella infection in the second trimester of pregnancy. Prenat Diagn 2003 Jun; 23(6):509-12.
2: O"Neill JF. The ocular manifestations of congenital infection: a study of the early effect and long-term outcome of maternally transmitted rubella and toxoplasmosis. Trans Am Ophthalmol Soc. 1998; 96:813-79.