[System for registering gestational trophoblastic disease in Chiba Prefecture in the past 20 years].

From 1974 to 1993, a total of 3,203 patients with hydatidiform mole (HM), were registered in Chiba Prefecture. The incidence of HM during the study period was 2.8 per 1,000 live births or one per 357 live births, but it decreased to 1.5 per 1,000 live births in these 3 years. In the past 20 years, the incidence of invasive mole (IM) and choriocarcinoma was 8.8% (282/3,203) and 0.91% (29/3,203), respectively. In addition, 1,599 patients with HM have been diagnosed and registered as complete mole (CM) and partial mole (PM) patients on the basis of macroscopic findings since 1981. Of these classified patients, the incidence of IM following CM and PM was 12.5% (141/1,130) and 1.5% (7/469), respectively. Moreover, 19 (1.7%) patients with CM and one (0.2%) patient with PM developed CC. In this study, it is clear that gestational trophoblastic disease after the evacuation of PM definitely occurred and the management of PM should be similar to that of CM so long as macroscopic criteria are employed.