Immunohistological demonstration of intermediate trophoblast in the diagnosis of uterine versus ectopic pregnancy: a retrospective survey and results of a prospective trial.

Immunohistological demonstration of human placental lactogen (hPL) in non-villous, mononuclear intermediate trophoblastic cells may be of routine diagnostic value, when chorionic villi are absent in endometrial curettings from patients suspected of miscarriage of an intrauterine pregnancy. The histological presence and distribution of hPL was investigated in endometrial curettings from 90 patients studied retrospectively (47 had ectopic pregnancies, 14 miscarriages, and 29 legal abortions), and a consecutive, prospective series of 50 patients (40 had miscarriages and 10 had ectopic pregnancies) without chorionic villi in their endometrial curettings. Non-specific background staining was not a problem. The retrospective survey disclosed that hPL was a highly sensitive marker of intrauterine pregnancy (sensitivity = 0.98). In the prospective series, the predictive value of positive staining for hPL for intrauterine pregnancy was 1.00, and the sensitivity of hPL, as an indicator of uterine gestation, was 0.62. In absence of specific hPL-staining, the risk of ectopic pregnancy was about 50%. The immunohistochemical demonstration of hPL is a useful tool for identifying patients who are suspected of having had a miscarriage, but for whom evidence in the form of chorionic villi in endometrial curettings is lacking.