Gamete intrafallopian transfer: the effect of the number of eggs used and the depth of gamete placement on pregnancy initiation.

The role of the fallopian tube in initiating pregnancy was examined in 246 consecutive gamete intrafallopian transfer (GIFT) cycles. Before actual transfer, the ampulla of each tube was measured to determine the depth at which gametes could be placed. Fifty-seven transfers were made with four oocytes into a single tube; of these, when gametes were deposited deeper than 4 cm, the pregnancy rate was higher than when they were placed at between 3 to 4 cm (69.6% compared with 41.2%). Presumably, a deeper placement is more secure and decreases the likelihood of gamete displacement. The pregnancy rate also rose with the number of oocytes used: from 0% with a single oocyte to 42.9% with four oocytes.