Routine pre‐evacuation ultrasound diagnosis of hydatidiform mole: experience of more than 1000 cases from a regional referral center

Abstract

To examine the accuracy of sonographic findings of routine ultrasound examinations in patients with a proven histological diagnosis of complete or partial hydatidiform mole referred to a supra-regional referral center, and to examine the relationship of sonographic findings to gestational age across the first and early second trimesters. Review of consecutive cases referred to a trophoblastic disease unit from June 2002 to January 2005 with a diagnosis of possible or probable hydatidiform mole in whom results of a pre-evacuation ultrasound examination were documented. Ultrasound detection rates for partial and complete hydatidiform moles were calculated and comparison of detection rates between complete and partial mole, and gestational age groups carried out. 1053 consecutive cases were examined. The median maternal age was 31 (range, 15-54) years and the median gestational age was 10 (range, 5-27) weeks. 859 had a final review diagnosis of partial or complete hydatidiform mole (82%), including 253 (29%) complete moles and 606 (71%) partial moles. Non-molar hydropic miscarriage was diagnosed following histological review in 194 (18%). Overall, 378 (44%) cases with a final diagnosis of complete or partial hydatidiform mole had a pre-evacuation ultrasound diagnosis suggesting hydatidiform mole, including 200 complete moles and 178 partial moles, representing 79% and 29%, respectively, of those with complete (253) or partial (606) moles in the final review diagnosis. The ultrasound detection rate was significantly better for complete versus partial hydatidiform moles (Z = 13.4, P < 0.001). There was a non-significant trend towards improved ultrasound detection rate with increasing gestational age, with an overall detection rate of 35-40% before 14 weeks' gestation compared to around 60% after this gestation. The sensitivity, specificity, positive predictive value and negative predictive value for routine pre-evacuation ultrasound examination for detection of hydatidiform mole of any type were 44%, 74%, 88% and 23%, respectively. Routine pre-evacuation ultrasound examination identifies less than 50% of hydatidiform moles, the majority sonographically appearing as missed or incomplete miscarriage. Detection rates are, however, higher for complete compared to partial moles, and improve after 14 weeks' gestation. Histopathological examination of products of conception remains the current gold standard for the identification of gestational trophoblastic neoplasia.