The presence of hepatitis B surface antigen and deoxyribonucleic acid in amniotic fluid and cord blood

OBJECTIVE: It is uncertain whether neonatal infection with hepatitis B, des pite treatment after delivery with immunoglobulin and vaccine, is the resul t of prior in utero transmission of the virus or treatment failure. Further more, the potential risk of hepatitis B transmission from the mother to the fetus at the time a genetic amniocentesis is performed is also a concern. In an attempt to better elucidate these controversies, amniotic fluid and c ord blood specimens obtained from pregnant women positive for hepatitis B s urface antigen were analyzed for the presence of hepatitis B surface antige n and hepatitis B deoxyribonucleic acid. STUDY DESIGN: This study was a prospective longitudinal analysis that ident ified hepatitis B surface antigen-positive patients who presented for amnio centesis. Cord blood was obtained from these patients at the time of delive ry. Cord blood was also obtained from a group of hepatitis B surface antige n-positive patients for whom no amniocentesis was performed. All samples we re analyzed for the presence of hepatitis B surface antigen and hepatitis B deoxyribonucleic acid. RESULTS: A total of 121 hepatitis B surface antigen-positive pregnant women were identified. In the 72 pregnancies in which amniocentesis was not perf ormed, 18% of the cord blood samples were positive for hepatitis B surface antigen and 4% were positive for hepatitis B deoxyribonucleic acid. Of 47 a mniocentesis fluid samples, 32% were positive for hepatitis B surface antig en but all were negative for hepatitis B virus deoxyribonucleic acid. Of 30 cord blood samples from patients who underwent an amniocentesis, 27% were positive for hepatitis B surface antigen, but all were negative for hepatit is B virus deoxyribonucleic acid. CONCLUSIONS: This study found that hepatitis B viral deoxyribonucleic acid is rarely present in cord blood and was not identified in amniotic fluid ob tained by amniocentesis. This finding suggests that in utero transmission o f the virus is rare prior to the onset of labor. These data further confirm the reports in the current literature that the risk of hepatitis B transmi ssion to the fetus during amniocentesis is low. Because hepatitis B surface antigen can exist as an isolated entity devoid of nuclear material, in som e cases this protein may be able to traverse the placental and amniotic mem brane barrier in a manner similar to other proteins, such as alpha -fetopro tein. Recommendations for genetic amniocentesis in women positive for hepat itis B surface antigen are discussed.