Immunohistochemical characterization of cells retrieved by transcervical sampling in early pregnancy

Trophoblastic cells can be retrieved from the endocervix and the lower uterine segment in early pregnancy by aspiration or lavage (Rodeck et al., 1995). The feasibility of using this technique for prenatal diagnosis depends on how frequently fetal cells can be retrieved and whether such cells can be purified from the predominant maternal cell population. In this study, specimens retrieved from the lower uterine segment prior to elective first‐trimester termination of pregnancy were examined histologically and characterized using a panel of monoclonal antibodies in an avidin‐biotin‐peroxidase technique. Lavage samples generally contained fewer cervical epithelial cells than aspirates. Syncytial fragments or cytotrophoblast were identified in 9 of 12 lavage samples but in only 4 of 10 aspirates. Trophoblast cells were reactive with various anti‐trophoblast monoclonal antibodies but the trophoblast cells present displayed considerable antigenic heterogeneity. For positive selection of trophoblast cells from these samples, it is likely that the best yield will be achieved by using a panel of carefully characterized monoclonal antibodies directed against various villous and extravillous trophoblast populations.