[Pregnancy and delivery after the transfer of one blastocyst with enzymatically removed zona pellucida].

OBJECTIVES: The embryonic development up to the blastocyst stage and hatching from zona pellucida are prerequisites for implantation and successful pregnancy. It is suggested that one of the possibilities limiting the implantation rate is impaired hatching. To overcome this problem an artificial alteration of the zona pellucida have been carried out in many laboratories. DESIGN: The report of the first pregnancy in Poland obtained after the transfer of enzymatically zona removed blastocyst. MATERIALS AND RESULTS: The patient was previously treated three times in in vitro fertilisation program without success. In the fourth program the embryos were cultured in co-culture of Vero cells to the blastocyst stadium. On the day 5 after insemination the zona of cavitating and expanding blastocyst was removed by pronase. The zona free blastocyst was transferred to the uterus. As a result of implanted blastocyst the ongoing pregnancy developed normally and the patient delivered healthy baby. CONCLUSION: Enzymatic zona pellucida hatching probably increases the rate of implantation. It is simple, safe and economic techniques.