Low Risk of Relapse After Achieving Undetectable hCG Levels in Women With Complete Molar Pregnancy

Complete hydatidiform molar pregnancies occur in approximately 1 of 1,000 conceptions. After uterine evacuation of the trophoblastic tissue, women are followed up with serial serum human chorionic gonadotropin (hCG) measurements. Patients are considered to have attained remission when their hCG level spontaneously declines to an undetectable level and remains there during a 6-month follow-up period. This standard effectively detects all disease recurrence; however, it is resource intensive, delays child bearing, and is subject to significant noncompliance. Our objective was to determine the risk of disease recurrence after hCG spontaneously declines to undetectable levels.We used a database from the New England Trophoblastic Disease Center to analyze hCG levels in patients with complete molar pregnancies.Among 1,029 women with complete molar pregnancy and complete data, 15% developed persistent gestational trophoblastic neoplasia. The rate of persistent neoplasm among those whose hCG level fell spontaneously to undetectable levels was 0.2% (2/876, 95% confidence interval 0-0.8%). No women developed persistent gestational trophoblastic neoplasia after their hCG level fell to undetectable levels using an assay with a sensitivity of 5 mIU/mL (n = 82, 95% confidence interval 0-4.5%).Based on our experience with women with complete hydatidiform molar pregnancies whose hCG values spontaneously fell to undetectable levels after molar evacuation, we conclude that the risk of recurrent neoplasm after hCG levels fall to less than 5 mIU/mL approaches zero.