An increase in in vitro fertilization ability of low-density human sperm capacitated by multiple-tube swim-up.

Comparison was made of the efficacy of multiple-tube swim-up (MT-SU) and single-tube swim-up (ST-SU) preparations on inducing human sperm fertilization ability in semen samples of less than 60 million motile sperm/ml. Two parallel groups of in vitro fertilization (IVF) patients possessing sperm density of this category had their sperm capacitated by MT-SU or ST-SU. The MT-SU patients' sperm fertilized 71 +/- 6.0% of eggs retrieved in comparison to 39 +/- 7.9% in the parallel ST-SU patients (P less than 0.001). Similarly, MT-SU increased the rate of human sperm penetration into zona-free hamster eggs. The increased fertilization rate of MT-SU sperm was not from acceleration of the acrosome reaction, but may be attributed to the higher efficiency of MT-SU in removing antifertility factors present in the seminal plasma from sperm.