STR genotyping diagnosis of hydatidiform moles: an assessment of 2871 consecutive products of conceptions

This study evaluated the incidence of hydatidiform moles in a tertiary care setting and examined the efficacy of short tandem repeat genotyping (STR) as a primary ancillary diagnostic tool for molar gestations. Consecutive products of conceptions undergoing genotyping were analyzed. A total of 2871 cases were analyzed, comprising 1693 in-house and 1178 consultation specimens. Patient ages ranged from 10 to 57 years (mean 32, median 33). Laser microdissection was performed in 138 specimens. STR genotyping yielded a definitive diagnosis in 99.5% of cases (2857/2871), classifying them as 282 complete moles (241 monospermic, 41 dispermic), 564 partial moles (546 dispermic, 12 monospermic, 6 triandric tetraploid), and 2006 non-molar gestations (including 125 trisomies, 24 digynic triploids, 4 egg donor conceptions, 1 trigynic tetraploid, 3 androgenetic/biparental mosaics, 2 chimeric twin gestations with a molar component of either monospermic complete mole or heterozygous partial mole, and 1 trigynic tetraploid). Among molar gestations, complete and partial moles accounted for 38.6% and 61.4% of in-house cases and 28.2% and 72.0% of consultation cases, respectively. Notably, complete moles occurred exclusively in patients younger than 15 or older than 50. The mean turnaround time for STR genotyping was 5.3 days overall (5.7 days for in-house and 4.8 days for consultation cases). Hydatidiform moles accounted for 29.4% of the study cohort in our tertiary care setting, with partial hydatidiform moles comprising two-thirds of these cases. With an average turnaround time of 5.3 days and a 99.5% success rate, STR genotyping demonstrated high efficiency in the accurate diagnosis and classification of hydatidiform moles.