Day 2 vs. day 3 embryo transfer after intracytoplasmic sperm injection. A prospective, randomized study.

OBJECTIVE: To compare, in a prospective, randomized study, implantation and pregnancy rates between day 2 and day 3 embryo transfer intracytoplasmic sperm injection (ICSI) STUDY DESIGN: A total of 106 patients undergoing ICSI cycles who had at least 1 embryo suitable for cryo-preservation were prospectively randomized into 2 groups: group 1, embryo transfer performed on day 2; group II, embryo transfer performed on day 3. RESULTS: Patient ages did not differ (P=.58) between groups I (33.1±4.5) and II (32.7±4.4). The number of oocytes retrieved from group I (13.7±5.2) was similar (P=.82) to that retrieved from group II (13.7±5.4). In addition, there was no difference (P=.30) in the number of oocytes retrieved at metaphase II between groups I (10.6±4.4) and II (97±4.2). Fertilization and cleavage rates were also similar (P=.58 and P=.50, respectively) between groups I (78.2±14.0% and 98.7±4.3%) and II (76.2±14.8% and 99.8±1.24%, respectively). The total number of embryos and of embryos transferred were similar (P=.22 and P=.36; respectively) for groups I (8.0±3.0, 2.8±0.7) and II (7.16±3.2, 2.6±0.8). Pregnancy rates per transfer, implantation rates and abortion rates were also similar for groups I (43.4%, 20.8% and 8.7%, respectively) and II (41.5%, 24.1% and 23%, respectively) (P=1.0, P=.57 and P = .24, respectively). CONCLUSION: The results suggest that extending the embryo culture period from 2 to 3 days for patients who had at least 1 embryo left for cryopreservation had no effect on implantation, pregnancy or abortion rates in an ICSI program.