EP21.21: How successful is our department in predicting hydatidiform moles on transvaginal ultrasound?

Complete hydatiform mole (CHM) and partial hydatiform mole (PHM) are premalignant conditions which, increase the need for intervention and follow up compared to a patient with a histologically normal first trimester miscarriage. The aim of this study was to ascertain our detection rate of HM on transvaginal ultrasound scan (TVS) to improve patient experience, counselling, and safe planning of surgical care, with specialised follow up. A retrospective cohort study was conducted in a tertiary London teaching hospital between January 2022 to December 2023. All women underwent TVS. Those with a suspected HM on TVS or HM confirmed on histology were included. We excluded patients where histological diagnosis or follow up was performed elsewhere. Our search resulted in 52 patients ranging from the age of 17 to 44 with the average gestational age of 7 weeks. During this study period 31 patients had a suspected HM on scan. 23/52 had a histologically confirmed HM. CHM was confirmed on histology in 7/52 cases, of which 6 had been suspected on TVS (sensitivity = 0.86 and PPV of 100%). PMH was suspected in 4 ultrasound scans and confirmed on histology in 16 patients (sensitivity = 0.25, PPV = 16%). This data therefore revealed a detection rate for complete molar pregnancy at of 86% and a detection rate for a partial molar pregnancy of 25%. Detection rates for CHM were comparable to other London teaching hospitals. The significantly lower detection rate of PHM reflects the difficulty in diagnosing PHM via ultrasound. Although we have a high index of suspicion of PHM, there are still a significant number of PHMs that we are not suspecting on US. We have considered this maybe because the clinician is focused on the parameter and diagnostics of miscarriage.