[Fertilization of cryopreserved and thawed human oocytes (Cryo-Oo) by injection of spermatozoa (ICSI)--medical management of sterility and case report of a twin pregnancy].

It is reported on a twin pregnancy and parturition of a healthy girl and a healthy boy following the treatment of the mother by intracytoplasmic injection of spermatozoa (ICSI) into cryopreserved and thawed human oocytes (Cryo-Oo). The couple suffered from a primary sterility because of a severe subfertility of the husband and oligomenorrhea with anovulation of the wife. Before the couple contacted our center for the first time, several pretreatments had been carried out, e.g. intrauterine inseminations (IUI) with husband's and donor sperm and one cycle of in vitro fertilization (IVF) with intracytoplasmic sperm injection. This IVF/ICSI-cycle resulted in a tubal pregnancy. It must be noted that the patient showed in each treatment cycle a remarkable tendency to develop ovarian hyperstimulation syndromes (OHSS), even under stimulation with 50 mg clomiphen citrate. In 1997 we started the first treatment cycle for IVF/ICSI with GnIZH-analogues and FSH according to the long protocol. In spite of a low dosage of gonadotropins the patient again developed a impressive multifollicular growth that we decided, together with the couple, only to perform the oocyte retrieval and cryopreserve the collected eggs. For ethic considerations the couple did not consent in the freezing of pronuclear stages. Two months later we performed the transfer-cycle: after thawing of four oocytes, the intracytoplasmic injection of native spermatozoa led to the fertilization of three oocytes and a total of three preimplantation embryos was transferred one day later. Two weeks later the blood level of hCG was 518 IU/ml and an intact twin pregnancy developed. In July 1998, after 36 weeks of gestation, a healthy girl (2540 g) and an healthy boy (2375 g) were delivered by cesarean section. This case report and the experience with further 23 patients (6 pregnancies) demonstrate that ICSI with cryopreserved and thawed oocytes is an effective approach to avoid repetitive oocyte retrievals. The achievable pregnancy rates so far seem to be similar to frozen pronuclear stages, possibly even better. Under the specific regulations of the German Embryo Protection Act (ESchG)--i.e. freezing of embryos not allowed--this technique is worth being pursued with attention.