Evaluation of a cut-off value for sperm motility after different hours of incubation to select the suitable reproductive technology (IVF or ICSI)

Background. The aim of this study was to enhance the predictability of conv entional semen parameters for in-vitro fertilization outcome. The utility o f late sperm motility in presence of a cumulus-oocyte complex after differe nt hours of incubation was investigated to predict the outcome of IVF in bo rderline and normal ejaculates (at least 5 x 10(6) motile sperm), Methods. The study was done on 52 infertile couples undergoing conventional in-vitro fertilization and embryo transfer. Sperm were prepared by the Per coll cushion centrifugation with swim-down. Cocultures were established by inseminating the cumulus-oocyte complexes with 100 000 motile spermatozoa a nd incubating them for 48 hours. Another 100 000 spermatozoa were incubated in culture medium for 48 hours. Sperm motility (WHO a + b) was determined at 0, 4, 24 and 48 hours of incubation. Results. The fertilization rate was 65.5% (42.9-88.1). The conventional sem en parameters did not correlate with the fertilization rate. Sperm motility measured after different hours of incubation was found to be significantly positively correlated with the fertilizing ability of sperm in vitro in Sp earman's rank correlation test: motility after 0 h (p < 0.02), after 3 h (p = 0.0025), after 24 h (n.s.) and after 48 h (p = 0.0071). Cut-off values f or late sperm motility were determined and differences in fertilization rat es were calculated for these cut-off values after different hours of incuba tion. A cut-off value of 20% progressive motile spermatozoa after 48 hours gave the best statistical power (fertilization rate 71.7 vs. 50.2%, p<0.001 ). Significant differences in the fertilization rates were also observed fo r a cut-off value of 35% after 24 hours of incubation (70.1 vs. 46.2%, p=0. 001) and for a cut-off point of 60% after 4 hours (72.4 vs. 51.5%, p=0.001) . Conclusions. The predictive power of sperm motility after 48 h for fertiliz ation outcome provides support in the decision-making process within the as sisted reproduction setting. If less than 20% Of sperm are motile after 48 h micromanipulatory techniques should be considered.