Schedule to inject in vitro matured oocytes may increase pregnancy after intracytoplasmic sperm injection

To ascertain the value of using immature oocytes in an intracytoplasmic spe rm injection (ICSI) program, the authors designed a schedule, at 5 p.m. on day 1 (the day of oocyte retrieval) and at 8 a.m. and 2 p.m. on day 2, to r ecognize and inject the in vitro matured (IVM) oocytes. For the 1166 oocyte s retrieved in 107 ICSI cycles, 128 (11.0%) were at the stage of metaphase I(MI) and 113 (9.7%) at germinal vesicle. Routine ICSI for metaphase ii ooc ytes was performed at 2 p.m. on day 1 (initial ICSI). In culture medium of human tubal fluid with 15% maternal serum, 85.1% (205/241) immature oocytes progressed to maturation in which 16.4% (21/128) of MI oocytes matured at 5 p.m. of day I. The rate of normal fertilization for IVM oocytes (58.5%) w as not significantly different from that of initial ICSI (64.0%). One patie nt received a transfer of two fertilized IVM oocytes alone that were inject ed at 5 p.m. of day 1, maturing from the MI stage, and achieved a normal pr egnancy. The fertilized IVM oocytes were replaced along with the embryos fr om initial ICSI for 40 cycles that led to 14 (35%) clinical pregnancies. In 43 fertilized IVM oocytes donated for research, we observed that cleavage (95.3%) to the 2- to 4-cell stage was not distinct from that of initial ICS I (94.6%); however, the percentage of embryos of grade I and II morphology was significantly smaller (24.4% vs. 62.5%). Only five (11.6%) developed to blastocysts in vitro. Twenty-one fertilized IVM oocytes were frozen for fu ture transfer. A schedule to inject IVM oocytes in ICSI cycles may generate more accessible embryos for fresh transfer or cryopreservation to increase the chance of pregnancy, although the embryo quality was relatively poor.