Sperm capacitation ability, as evaluated by Cap-Score™, has little impact on ICSI success

Men with low capacitation ability have reduced conception through intercourse, IUI, and conventional IVF and are often referred for ICSI. This study evaluated whether reduced capacitation ability, as measured by Cap-Score, impacts ICSI outcomes.

Retrospective review of 199 men undergoing ICSI at a single clinic (2018-2023). Semen analysis included Cap-Score. Fertilization and euploidy rates were compared for low vs normal Cap-Scores and abnormal vs normal semen analyses. Following frozen embryo transfer, Cap-Scores and semen analysis outcomes were compared between positive and negative pregnancy indicators. Multiple and logistic regression assessed whether male and female factors, including Cap-Score, independently predicted fertilization, euploidy, hCG positivity, or clinical pregnancy.

Fertilization (82 ± 1.9 vs 80 ± 1.6%; p = 0.40) and euploidy rates (43 ± 5.1 vs 34 ± 3.3%; p = 0.13) were similar for those with low vs normal Cap-Scores. Cap-Scores did not differ for negative vs positive hCG (30 ± 1.2 vs 30 ± 1.0%; p = 0.96), clinical pregnancy (30 ± 1.0 vs 30 ± 1.1%; p = 0.83), or ongoing pregnancies/live birth (30 ± 1.0 vs 30 ± 1.1%; p = 0.92). Fertilization and pregnancy outcomes were independent of semen analysis results. Multiple regression showed fertilization was associated only with female age and number of oocytes retrieved (R² = 6.8; p = 0.002), and euploidy with female age and percent sperm motility (R² = 24.5; p < 0.001). Logistic regression showed no independent association between Cap-Score and hCG (R² = 6.18; p = 0.054) or clinical pregnancy (R² = 5.28; p = 0.032).

Within this cohort and analytical framework, no association was detected, supporting the conclusion that men with low Cap-Scores can be counselled that their ICSI outcomes are comparable to those with normal scores.