Background: To ascertain the influence of the duration of the 'interval loading-discharging embryos' (ILDE) on the results of embryo transfer.
Methods: The population under study consisted of 450 consecutive fresh embryo transfers. ILDE was measured in all transfers. Pregnancy and implantation rates were analyzed.
Results: Conceptional cycles had a lower (mean +/- SD) ILDE than non conceptional cycles (53.5 +/- 43.6 s vs 63.7 +/- 49.3). When only easy transfers--defined as those not requiring cervical tenaculum--were considered, similar differences were observed. The following pregnancy rates were obtained according ILDE duration: 38.9% (ILDE < 30 s), 33.2% (ILDE 31-60), 31.6% (ILDE 61-120) and 19.1% (ILDE > 120) (P < 0.05). When only easy transfers were considered, similar results were obtained: 40.0%, 33.3%, 32.0% and 19.4%, respectively. Similar results were observed regarding implantation rates regarding the whole population (21.2%, 15.4%, 15.9% and 9.4%, respectively; P < 0.01) as well as when only easy transfers were considered.
Conclusions: ILDE duration is a prognostic factor of pregnancy rate and of implantation rate in IVF. The longer the ILDE duration, the lower the pregnancy and implantation rates. The decrease in pregnancy and implantation rates is gradual until an ILDE of 120 s, and decreases sharply afterwards. It is recommended to speed up the embryo transfer process, wherever possible. ILDE > 120 s carries a poor prognosis and should, when possible, be avoided.