OBJECTIVETo investigate the effects of the computer-assisted semen analysis (CASA) on human sperm movement parameters at different times after semen collection.

METHODSNinety-two semen samples with sperm density > or = 20 x 10(6)/ml and sperm liquefaction time < 20 min were placed in a incubation box at the temperature of 37 degrees C. Then the seminal parameters were analyzed with the computer-assisted semen analysis (CASA) system at 20, 30, 60 and 90 min after semen collection.

RESULTSThe percentages of grade a and b sperm were significantly lower at 30, 60 and 90 min than at 20 min (P < 0.05), so were the percentages of grade c sperm at 60 and 90 min than at 20 and 30 min (P < 0.05), but there were no significant differences in the percentage of grade c sperm between the 20-min and 30-min groups (P > 0.05). The percentages of grade a + b and a + b + c sperm were also significantly lower at 30, 60 and 90 min than at 20 min (P < 0.05). The beat cross frequency (BCF) was significantly higher at 30 min than at 20 min (P < 0.05), while the lateral head amplitude (ALH) significantly lower at 90 min than at 30 min (P < 0.05). The sperm wobbliness (WOB) was significantly higher while the curvilinear velocity (VCL) significantly lower at 90 min than at 20 and 30 min (P < 0.05). Straightness (STR) at 30, 60 and 90 min, and average path velocity (VAP) and straight line velocity (VSL) at 90 min were significantly lower than at 20 min (P < 0.05). There were no significant differences in sperm density, average motion degree (MAD) and linearity (LIN) among the four groups (P > 0.05).

CONCLUSIONThe interval between semen collection and sperm routine analysis needs to be standardized. The results of this study suggest that sperm movement parameters of normal liquefied semen samples are relatively constant at 30 -60 min after semen collection.