Prenatal diagnosis of rubella

Fetal blood sampling in human immunodeficiency virus--seropositive women before elective midtrimester termination of pregnancy

OBJECTIVES

To explore the diagnostic potential of fetal blood sampling in the prenatal diagnosis of intrauterine human immunodeficiency virus infection and to investigate the transplacental transfer of human immunodeficiency virus antibody and p24 antigen in the second trimester of pregnancy, we studied serum and amniotic fluid obtained from 13 seropositive women and their fetuses before elective termination of pregnancy.

STUDY DESIGN

Enzyme-linked immunosorbent assay, Western blot antibody analyses, and p24 antigen assays were performed on all samples.

RESULTS

Human immunodeficiency virus antibody was detected by enzyme-linked immunosorbent assay and Western blot analysis in aliquots of maternal serum, amniotic fluid, and fetal serum from all 13 pregnancies. Each mother-fetus pair had identical antibody banding patterns. In contrast, p24 antigen was found in the maternal serum and amniotic fluid samples from five of 13 women (38%) and in serum from only three of 13 fetuses (23%).

CONCLUSIONS

We conclude that fetal blood sampling, if combined with sophisticated serologic analysis, may have the potential to provide the diagnosis of congenital infection with human immunodeficiency virus. The correlation of immunologic, virologic, and molecular biologic methods with subsequent infant outcome and risk of iatrogenic infection of the fetus remains to be determined.

Fetal infection after maternal reinfection with rubella: criteria for defining reinfection

Five cases of asymptomatic maternal reinfection with rubella are described that occurred in England and Wales during 1985-8 and resulted in intrauterine infection. The criteria for diagnosing reinfection are described. In four cases the rubella contact was with the woman's own children. Two women had therapeutic abortions, rubella virus being recovered from the products of conception, and three were delivered of infants with congenitally acquired disease. Though the risks associated with maternal reinfection with rubella are very small and being measured in a prospective study, it is hoped that the recently introduced augmented programme of rubella vaccination will reduce rubella in the community and therefore this small risk still further.

Fetal evaluation by percutaneous blood sampling

Percutaneous umbilical blood sampling (cordocentesis) provides direct access to the fetal circulation in the second and third trimesters of pregnancy. Seventeen patients underwent this procedure between December 1985 and December 1986 for evaluation of a variety of clinical situations, including nonlethal fetal abnormalities detected by ultrasound, equivocal results of amniocentesis, nonimmune fetal hydrops, and isoimmune disorders. Our experience confirms the efficacy of the procedure and suggests that it may become an important tool for fetal assessment and therapy.

Prenatal diagnosis of intrauterine rubella

The results of prenatal diagnosis of fetal rubella infection by specific IgM antibody detection in fetal infection by specific IgM antibody detection in fetal blood obtained in the 21st to 23rd weeks of pregnancy of women with different types of rubella problems during pregnancy (categorised in four groups) showed that in 28 of 31 cases the diagnosis apparently assisted in the correct management of the pregnancy. However, in two cases with negative IgM findings in the fetal blood, children with rubella embryopathy were born, and in one case with positive IgM antibody findings, the child was infected but healthy. From this experience we recommend that in all cases of symptomatic rubella infection in the first 12 weeks, termination of pregnancy should be considered without prenatal diagnosis. Prenatal diagnosis, if considered at all, should be limited to "symptomless" acute rubella infection and reinfection in the first 12 weeks and to symptomatic rubella infection in the 12th to 17th weeks of pregnancy.

Detection of IgM antibodies against rubella virus: comparison of two indirect ELISAs and an anti-IgM capture immunoassay

A commercial antibody capture enzyme immunoassay (Rubenz M) was compared to two commercial indirect enzyme immunoassays (Enzygnost IgM, Rubazyme-M) for the detection of rubella-specific IgM. Five hundred and fifty-two sera collected between the day of onset and 272 days after the onset of the exanthem of primary rubella were tested. Rubenz M was more sensitive early and late after the onset of the exanthem than the two indirect ELISAs. Rubenz M also appeared more sensitive when 240 sera were examined from patients with possible rubella in pregnancy, reinfection in pregnancy, suspected intrauterine infection, and recent vaccination. However, 5.5% of 968 pregnant women with no history of rubellalike symptoms or recent vaccination, the majority with elevated HAI titers, gave a low-positive or borderline result with Rubenz M. None of these women delivered a congenitally infected child. Therefore, borderline and low-positive results must be interpreted with caution, as for any assay for rubella-specific IgM.