Diagnosis of congenital cytomegalovirus infection by examination of placenta: application of polymerase chain reaction and in situ hybridization.

We examined the placentas of 12 patients in whom congenital cytomegalovirus (CMV) infection was suspected from serological and/or pathological evaluation. Seven patients died (including four intrauterine deaths) and five survived. On histological examination, the characteristic inclusion bodies were detected in only three placentas, and villitis with plasma cell infiltration was seen in eight placentas. Immunohistochemistry using a specific antibody against CMV improved the sensitivity of CMV deletion (10 cases were positive). With the polymerase chain reaction (PCR) following the extraction of DNA from formaldehyde-fixed placenta samples, CMV DNA was detected in seven cases. All 12 subjects were diagnosed with CMV infection by additional Southern blot analysis after the PCR. CMV DNA was also detected by an in situ hybridization method in all cases. With current molecular biological techniques the placenta can be reliably used for the diagnosis of congenital CMV infection.