The Value of Motile Density, Strict Morphology, and the Hypoosmotic Swelling Test in in Vitro Fertilization-Embryo Transfer

This study was conducted to evaluate the effect of a single abnormal semen parameter on subsequent implantation and pregnancy rates (PRs) following in vitro fertilization-embryo transfer (IVF-ET). The parameters evaluated were motile density (MD), strict normal morphology (SNM), and the hypoosmotic swelling (HOS) test. A total of 592 IVF cycles were evaluated. Patients were divided into four groups each with one abnormal semen parameter except for the control: group 1 (n = 509), control group: MD ≤ 10 × 106/mL, HOS ≤ 50%, SNM ≤ 4%; group 2 (n = 51): HOS and SNM normal, MD < 10 × 106/mL; group 3 (n = 14): MD and SNM normal, HOS < 50%; group 4 (n = 18): MD and HOS normal, SNM > 4%. The implantation rate was 10.2% for the control group. The implantation rate was similar for the low MD (9.0%) and the low SNM (16.7%) groups. However, the low HOS group had a significantly lower implantation rate (0%). The clinical PRs are similar in the control group and low MD and SNM groups, but decreased in the low HOS group (21.5, 15.0, 30.8, and 0%, respectively). Ongoing PRs were also similar with the exception of the low HOS group (0%). This comparative study supports previous conclusions that the subnormal HOS test is the best semen parameter available that predicts poor PRs. It also suggests that some qualitative defect in the embryos may result from defective sperm membranes, resulting in an apparently normal appearance but physiologically defective embryo.