Methodological aspects of sperm morphology evaluation: comparison between strict and liberal criteria.

OBJECTIVE

To compare the methodological accuracy of different sperm morphology criteria.

SETTING

A multicenter study including 10 laboratories with high expertise in semen analysis.

PATIENTS

Semen preparations of subfertile men with a variable degree of teratozoospermia and of fertile semen donors.

INTERVENTIONS

Detailed assessment of sperm morphology on 10 air-dried semen smears, of which 3 originated from the same ejaculate.

RESULTS

The average coefficient of variation calculated on the three smears of the same ejaculate was higher when strict criteria for morphological normality were used and borderline cells were classified as abnormal than when criteria of abnormality were applied and borderline cells were considered normal. The correspondence between individual centers mutually and of each center with the average result of all centers was better when the latter approach was taken. The performance of two computer-assisted systems was intermediate between that of the two approaches, whereas one system gave unreliable results.

CONCLUSIONS

Strict criteria for normality of sperm morphology, with borderline cells considered abnormal, gives results that are less reproducible and less accurate than the approach that classifies sperm as abnormal, with borderline cells considered normal.