Appraisal of hydatidiform mole incidence and registration rates in Ireland following the establishment of a National Gestational Trophoblastic Disease Registry.

Aims: This study aimed to re-evaluate the incidence of hydatidiform mole (HM) and determine gestational trophoblastic disease (GTD) registration rates in Ireland following the establishment of the National GTD Registry in 2017.

Methods: We performed a 3-year retrospective audit of HM cases (January 2017 to December 2019) reported in our centre. In 2019, we surveyed Irish pathology laboratories to determine the number of HMs diagnosed nationally and compared this data to that recorded in the National GTD Registry. Additionally, we compared both local and national HM incidence rates to those reported internationally.

Results: In the 3-year local audit, we identified 87 HMs among 1856 products of conception (POCs) providing a local HM incidence rate of 3.92 per 1000 births. The 1-year pathology survey recorded 170 HMs in 6008 POCs, yielding a national incidence rate of 2.86 per 1000 births. Importantly, the local HM incidence rate exceeded the national incidence rate by 37% and the local partial HM incidence (1 in 296 births) was 64% higher than the nationally incidence rate (1 in 484 births). Notably, 42% of the HM and atypical POCs diagnosed nationally were not reported to the National GTD Registry.

Conclusions: Our study reveals increased HM incidence rates both locally and nationally compared with previous Irish studies. The higher local PHM incidence may reflect more limited access to ploidy analysis in other pathology laboratories nationally. Significantly, almost half of the women with diagnosed or suspected HM were not registered with the National GTD Centre.