Sperm morphology assessment using David's classification: time to switch to strict criteria? Prospective comparative...

The aim of this study was to compare assessment of sperm morphology by using David's classification (DC), a method of manual analysis most common in France, with a computer-assisted method (Integrated Visual Optical System) based on the strict criteria (CASA SC) for their ability to predict fertilization in a selected in vitro fertilization (IVF) population. A total of 120 couples engaged in IVF protocols were prospectively included in the study. To focus mainly on sperm morphology, couples were excluded in cases of abnormalities of sperm concentration and/or motility and immunological factors and when a low number of oocytes were collected. Sperm morphology analysis was performed on the day of oocyte retrieval by the same trained biologist. Our results showed a moderate correlation between the two techniques (r = 0.49). The DC sperm morphology analysis was less indicative of fertilization than CASA SC (r = 0.07, p = 0.47 vs. r = 0.22, p = 0.014). Using receiver-operating characteristics analysis, we showed that DC was not discriminating in the prediction of fertilization (AUC = 0.572). DC seemed less appropriate for the prediction of fertilization success or failure. In contrast, with CASA SC, the previously determined cut-off value of around 14% was confirmed (AUC = 0.735, cut-off = 6%). Our results argue in favour of the replacement of DC by SC to tend towards worldwide standardization.