Cytological detection of trophoblasts for rapid diagnosis of pregnancy of unknown location

Abstract

Diagnostic uterine curettage and pathological examination of the specimen can be used when a pregnancy's location is unknown. However, it may take a few days to confirm the histopathological diagnosis, and frozen section examination sometimes leads to false-negative results due to a limited specimen [1]. The aim of the present study was to evaluate the utility of cytodiagnosis of uterine specimens to differentiate between ectopic pregnancy and spontaneous abortion. Between January 1, 2000, and April 30, 2011, 22 women who had been diagnosed with a pregnancy of unknown location and were of stable physical status were examined. Normal gestation had been excluded, but a definitive diagnosis could not be made by ultrasound or quantitative human chorionic gonadotropin (hCG) test. The patients provided informed consent and the study received approval from the hospital's ethical review board. Uterine specimens were prepared by direct imprinting of suctioned or curetted uterine contents onto glass slides in 18 patients, while in 4 patients the samples were collected from the endometrium using cell samplers. All samples were stained with Papanicolaou stain and the cytological findings were confirmed within 1–2 hours on the same day they had been collected. The specimens were judged positive, suggestive of spontaneous abortion, if 1 or more syncytiotrophoblasts were detected (Fig. 1). The uterine specimens were also sent for histologic examination for confirmation of the diagnosis. Syncytiotrophoblasts (STs) in the specimens of suctioned uterine contents: (a) STs with a large cell cluster. Tadpole-like multinucleated large cells are characteristic of STs; (b,c) Scattered small STs (Papanicolaou stain × 200). Seven specimens were judged to be positive cytologically and in all cases the final diagnosis was spontaneous abortion. In 5 cases the histological diagnosis confirmed spontaneous abortion, while in 2 cases no chorionic villi were found histologically despite positive cytology; however, spontaneous abortion was confirmed by a promptly declining hCG value after curettage. Fifteen specimens were judged to be negative for chorionic villi both cytologically and histologically. Of these, 3 were diagnosed as complete spontaneous abortion, while 12 were finally diagnosed as ectopic pregnancy. Seven of these 12 patients had elective surgery and 5 were treated successfully with methotrexate (MTX). None of the patients had complications of significant intraperitoneal bleeding from a ruptured ectopic pregnancy. Previous reports on the use of cytodiagnosis in cases of pregnancy of unknown location concluded that the diagnostic procedure was helpful in differentiating between ectopic pregnancy and spontaneous abortion [2,3]. Although false-positives cannot be excluded because trophoblasts may migrate from ectopic implantation sites into the uterine cavity, such cases are considered uncommon. Early differentiation of pregnancy of unknown location has become more important because it facilitates successful MTX therapy for ectopic pregnancy and reduces unnecessary MTX therapy for spontaneous abortion. Cytological detection of trophoblasts is a rapid, low-cost, and reliable diagnostic tool to evaluate patients in whom the location of pregnancy is unknown. The authors have no conflicts of interest to declare.