P-50: How does the number of oocytes retrived affect the outcome in ART?

Abstract

The aim of this study was to determine the suitable range of oocytes retrieved that would yield high pregnancy rates. Retrospective observational study. In a retrospective study we analysed 438 ICSI cycles that resulted in a total of 3575 oocytes retrieved from January 2000 to December 2005. The cycles were stratified into four ranges according to the number of oocytes retrieved. Group 1: 1 to 3 oocytes (n=75); group 2: 4 to 6 oocytes (n=125); group 3: 7 to 10 oocytes (n=111) and group 4: more than 11 oocytes (n=127). Ovulation induction, laboratory techniques, embryo culture and transfer protocols were identical in all groups. Main outcome measures were age, total doses of gonadotrophins, number of oocytes metaphase II retrieved, total number of embryos available for transfer, total number of good quality embryos (grades 1 or 2) transferred, fertilization rate and pregnancy diagnosed by a positive hCG serum test at least 14 days after the transfer. Values were expressed as mean ± SD. ANOVA and Fisher exact tests were used. The mean female age and the total doses of gonadotrophins were significantly higher in groups 1 and 2 compared to groups 3 and 4. The fertilization rate was significantly higher in group 1 compared to groups 2, 3 and 4. The lower number of oocytes retrieved was associated with a significant decline in the number of oocytes metaphase II and good quality embryos transferred. Group 1 had a statistically significant reduction in pregnancy rates when compared to the others. However, no significant differences were found in pregnancy rates among groups 2, 3 and 4, despite the fact that more embryos had been tranferred in the groups 3 and 4 compared to group 2 (table 1).Tabled 1 The retrieval of at least 4-6 oocytes per patient is reasonable to maximize the satisfactory rates in patients undergoing ICSI cycles. This should be taken into account when counseling poor responding patients regardless of woman’s age.Tabled 1