Prenatal diagnosis and outcome of congenital cytomegalovirus infection in twin pregnancies

Objective: To study the outcome of 20 twin pregnancies with evidence of primary or recurrent cytomegalovirus (CMV) infection during pregnancy. Design: Observational study. Setting: Two tertiary perinatal departments in Israel. Population: Twenty women with twin pregnancies who were referred because of serologic investigation indicating CMV infection. Seventeen women had evidence of primary CMV infection, and three women appeared to have recurrent CMV infection. Methods: Prenatal diagnosis was made by amniocentesis of both sacs after 21 weeks of gestation. CMV isolation was performed by culture on fibroblasts, shell vial technique and polymerase chain reaction (PCR) amplification of CMV DNA. After birth, the neonatal urine and saliva were cultured for CMV. Main outcome measures: Intrauterine CMV infection defined as positive PCR at amniotic fluid analysis and congenital CMV infection defined as positive CMV cultures after birth. Results: Except for one, all women underwent amniocentesis of both gestational sacs. In 14 (70%) women, no evidence of vertical transmission to any of the 28 fetuses was found and none of the newborns had evidence of congenital CMV infection. Intrauterine infection was detected by amniocentesis in five women and by ultrasound findings with positive maternal serology in one. In three women, CMV was detected in only one amniotic sac. In five of our six total cases, both twins were found to have congenital CMV infection at birth, all of whom had dichorionic-diamniotic placentation, three fused and two separate. Conclusions: In twin gestations, as in singletons, intrauterine and congenital CMV infection occurs in about 30% of women with primary or recurrent infection. The placenta type did not predict if one or both twins would be infected. Our data do not exclude the possibility that intrauterine transmission of the virus from one fetus to the other can occur.