Medical induction prior to surgical evacuation of hydatidiform mole: is there a greater risk of persistent trophoblastic disease?

A retrospective study was undertaken to assess whether stimulation of uterine contractility prior to surgical evacuation of a molar pregnancy will lead to an increased frequency of persistent trophoblastic disease. Forty-seven patients treated with chemotherapy for persistent trophoblastic disease after a hydatidiform mole between 1971 and 1988 were evaluated. The use of medical methods in this study group was compared to a control group of 219 patients with hydatidiform mole not requiring further treatment. A medical method, mainly treatment with prostaglandins, was used in 61.7% in the study group compared to 35.2% in the control group. This difference was, however, due to different stage distribution in the groups. Persistent disease was significantly correlated to uterine size and medical methods were mainly used in patients where uterine size corresponded to 15 weeks gestation or more. In this subset of patients, a medical method was used in the same frequency in both groups. Thus, large uterine size seems to be an independent risk factor. We conclude that stimulation of uterine contractility, which in Sweden is frequently used before surgical evacuation of the uterus in patients with hydatidiform mole and large uteri, carries no additional risk.