Andrology: Semen parameters as predictors of in-vitro fertilization: the importance of strict criteria sperm morphology

This study evaluated 120 couples undergoing in-vitro fertilization treatment to determine which semen parameter(s) predicted fertilization and whether there was any consistent relationship between strict criteria and standard assessment of sperm morphology. Strict criteria morphology was the only significant predictor of fertilization (P = 0.0006, r2 = 0.09), with a sensitivity of 94% and a specificity of 40%. A 12% cut-off point presented a negative predictive value of 98% and a positive predictive value of 22%. The probability of satisfactory fertilization is 40% with morphology <4%, which increases to 97% with normal morphology (>=12%). The receiver operating characteristic curve deviated significantly from the diagonal with a 76% area under the curve, making this a superior predictive test. This was augmented by likelihood ratios (LR) of 8. 25 (LR+) for results with <4% normal morphology and 0.15 (LR-) for results with >/= 12% normal morphology by strict criteria. While there was some correlation between strict criteria and standard assessment of morphology (r = 0.35), the former explained only 12% (r2 = 0.12) of the variability in the latter. This study concludes that strict criteria morphology predicts fertilization, while other semen parameters do not. A 12% cut-off point makes strict criteria morphology an excellent predictor of satisfactory fertilization, while a value <4% is a good predictor of poor fertilization.