This new procedure principally aims to avoid a second or possibly multiple surgical procedures for sperm extraction from the male partner in cases of limited amounts of sperm cells, where normal freeze-thaw protocols would fail. Patients (n = 34) diagnosed as azoospermic, extreme oligozoospermic, or oligoasthenozoospermic underwent the process of sperm cryopreservation within evacuated egg zonae. Other samples were allocated to conventional sperm freezing. Sperm samples were acquired using testicular sperm extraction (TESE), microepididymal sperm aspiration (MESA), or fresh ejaculate. Subsequently, five of these 34 couples have undergone in-vitro fertilization (IVF) and achieved normal fertilization using post-thawed spermatozoa frozen under zonae pellucidae in conjunction with intracytoplasmic sperm injection (ICSI). The average fertilization rate for the post-thaw injected spermatozoa was 65%. This is comparable with the regular fertilization rate of 65% for combined MESA and TESE using fresh spermatozoa. All patients underwent embryo transfer. The average implantation rate per embryo was 31%; nearly the same for regular MESA/TESE ICSI cycles (32%). The first pregnancy associated with this procedure concluded with the full term delivery of healthy twin girls on July 18, 1997. The remaining four thaw procedures resulted in another twin delivery, an ongoing singleton gestation, a negative pregnancy test and a biochemical pregnancy respectively.
