Risk factors for mismatches in the ART laboratory: an analysis of 73,719 electronic witnessing points

RESEARCH QUESTION: What are the risk factors for mismatches (involving or not involving biological material) and critical mismatches (CMM; involving biological material) in an assisted reproductive technology laboratory equipped with an electronic witnessing system (EWS)? DESIGN: In total, 73,719 witnessing points were extracted retrospectively from an EWS database, representing 11,210 consecutive treatment cycles performed at Fertility North between January 2016 and July 2023. RESULTS: Overall, 138 (0.19%) mismatches and 16 (0.02%) CMM were identified during the study period. Significant differences were detected in both mismatch (P = 0.003) and CMM (P = 0.038) rates between different time periods of the day. The mismatch rate was highest between 12 pm and 2 pm (0.28%), whilst the CMM rate was highest after 4 pm (0.13%). Neither mismatches nor CMM were associated with a specific weekday or weekend day/public holiday (P = 0.886 and 0.183, respectively). Both mismatch (P < 0.001) and CMM (P < 0.001) rates differed significantly between eight laboratory processes. The mismatch rate was highest during embryo transfer (0.36%), and the CMM rate was highest during oocyte denudation (0.13%). Furthermore, the mismatch rate differed significantly between 20 operators (P < 0.001), whereas the CMM rate did not (P = 0.216). Multivariate logistic regression found that six laboratory processes [in the order from higher to lower risk, oocyte denudation (P < 0.001), embryo transfer (P < 0.001), cryopreservation (P = 0.002), sperm preparation (P = 0.003), oocyte collection (P = 0.007) and insemination (P = 0.006)] and four individual operators (P = 0.005, 0.037, 0.010 and 0.048, respectively) were associated with mismatches. On univariate regression analysis, time after 4 pm (P = 0.020) and oocyte denudation (P < 0.001) were the only risk factors associated with CMM. CONCLUSIONS: Mismatches are associated with specific laboratory processes and individual operators, while CMM are associated with time after 4 pm and oocyte denudation.