Intrauterine insemination in fertile women delivers larger number of sperm to the peritoneal fluid than intracervical insemination.

Randomized IUI or intracervical insemination of eight fertile women with 50 x 10(6) sperm was performed to determine whether IUI delivers more spermatozoa to the peritoneal cavity. After IUI (n = 4), 2,053 to 29,450 sperm were recovered in the PF at laparoscopy. No sperm were found in the PF after intracervical insemination (n = 4). After IUI, CM contained 1.0 x 10(6) to 57.0 x 10(6) sperm/mL; after intracervical insemination, 0 to 1.2 x 10(3) sperm/mL were seen. One therapeutic mechanism for IUI is delivery of larger sperm numbers to the fertilization site by rapid (4 hours) transport. In addition, there is greater retrograde colonization of CM that may result in sustained release of sperm.