Success rate in gamete intrafallopian transfer using low and high concentrations of washed spermatozoa

The effect of a reduced number of spermatozoa on pregnancies and miscarriages was studied retrospectively in 307 consecutive gamete intrafallopian transfer (GIFT) cycles. The number of spermatozoa introduced per GIFT in each group was as follows: 100,000 (group I), 50,000 (group II), 10,000 (group III), 5,000 (group IV), and 2,500 (group V), which gave a pregnancy rate of 20%, 38%, 37%, 30%, and 24%, respectively (differences were not significant). With respect to the pregnancies, no correlation was found between the number of spermatozoa transferred and the cause of infertility. In the male factor group also no significant difference was observed in the pregnancy rate when the sperms were reduced from 100,000 to 2,500. Lowering the number of sperms in GIFT did not reduce the abortion rate, which remained around 33%. It was the patients with unexplained infertility who benefited most from the GIFT procedure. Their pregnancy rate was significantly higher than the pregnancy rate of those who had endometriosis, or andrologic or immunologic disorders.