Sonographic appearance of first trimester complete hydatidiform moles

Objective Complete hydatidiform moles are now being diagnosed earlier in gestation, thus the clinical presentation and pathologic findings of complete molar pregnancy have changed. We studied the sonographic appearance of first trimester moles and the ability of ultrasound to detect them. Methods We reviewed the sonographic interpretation and sonograms, when available, from all patients with first trimester complete moles diagnosed at our institution from January 1988 to March 1996. Results Of the 24 patients in gestational age at time of the sonogram was 8.7 +/- 2.0 weeks (mean +/-SD) with a range of 5.7-12.3 weeks. The initial sonographic interpretation was a complete mole in 17 (71%) cases, partial mole versus failed pregnancy in two (8%), and failed pregnancy in five (21%) cases. Of the 22 patients with sonograms available for review interpretation on review of the images was a complete mole in 18 (82 %) cases, partial mole versus failed pregnancy in one (5%), and failed pregnancy in three (14%) cases. The typical sonographic appearance of a first trimester complete mole was a complex, echogenic, intra-uterine mass containing many small cystic spaces. Conclusion The majority of first trimester complete moles demonstrate a typical ultrasound appearance such that the diagnosis can be made with ultrasound in most cases.