Consistency in rates of diagnosis of embryonic mosaicism, segmental abnormalities, and “no call” results among experienced embryologists performing preimplantation genetic testing for aneuploidy

OBJECTIVE: To determine whether differences exist in rates of subchromosomal abnormalities, mosaicism, and “no call” results among embryologists performing and loading trophectoderm biopsies for preimplantation genetic testing for aneuploidy (PGT-A). DESIGN: Retrospective cohort. SETTING: Large infertility center. PATIENT(S): All patients undergoing in vitro fertilization with PGT-A. INTERVENTION(S): The NexCCS next generation sequencing platform was used for PGT-A. The χ(2) testing assessed differences in rates of primary outcomes between embryologists. Intraclass correlation coefficients evaluated inter-embryologist reliability in rates of abnormal and no call results. Median absolute performance difference (MAPD) scores, which quantify the impact of technical variation on analytical performance, were averaged for individual embryologists. Analysis of variance assessed differences in mean MAPD scores. MAIN OUTCOME MEASURE(S): Interoperator variability in rates of mosaic, segmental, and no call results. RESULT(S): Four embryologists performed 30,899 biopsies and 6 embryologists loaded specimens into designated tubes. Among individuals performing trophectoderm sampling, rates of mosaicism were 4.3% to 6.1%, segmental errors were 9.0% to 10.7%, and inconclusive results were 1.1% to 2.9%. For those loading, the incidence of mosaicism was 4.2% to 5.9%, subchromosomal abnormalities was 9.7% to 10.4%, and no call results was 1.2% to 2.2%. The intraclass correlation coefficient was 0.978 for embryologists performing biopsies and 0.981 for those loading. Differences in mean MAPD scores were within 0.6% and 0.2% of each other for doing biopsies and loading embryologists, respectively. CONCLUSION(S): Rates of mosaicism, segmental, and no call PGT-A results are consistent among experienced embryologists. Due to the large sample size included, differences within 1% of the mean were deemed clinically irrelevant despite statistical significance.