The diagnostic implications of routine ultrasound examination in histologically confirmed early molar pregnancies.

Objective: Early ultrasound examination is being used increasingly in the diagnosis of molar pregnancy. The aim of this study was to examine the diagnostic implications of routine ultrasound examination for histologically confirmed molar pregnancies.

Methods: This was a retrospective review of sonographic and histological findings in a series of consecutive cases referred to the National Trophoblastic Disease Surveillance Centre with suspected molar pregnancies. In 194 cases referred to the center over a 6-month period in whom results of a preceding ultrasound examination were documented, review of ultrasound findings and final histological diagnosis was carried out.

Results: There were 155 cases with a reviewed histological diagnosis of complete or partial hydatidiform mole. In 131 (67%) cases, the sonographic diagnosis was that of a missed miscarriage/anembryonic pregnancy with no documented suspicion of molar pregnancy, referral being on the basis of histological examination of products of conception. In 63 cases, ultrasound examination suggested molar pregnancy; in 53 (84%) of these, the diagnosis of molar pregnancy was correct. Overall, 37 of 64 (58%) complete moles had sonographic evidence of molar pregnancy compared to 16 of 91 (17%) partial moles. Of 155 histologically confirmed complete or partial hydatidiform moles, only 53 (34%) were suspected as molar sonographically.

Conclusion: The majority of cases of molar pregnancy now present as missed miscarriage/anembryonic pregnancy sonographically, highlighting the importance of histological examination to diagnose gestational trophoblastic disease.