Utilization of retrieved oocytes as an index of the efficiency of superovulation strategies for in-vitro fertilization treatment.

An analysis of 581 in-vitro fertilization treatment cycles was carried out to determine the pattern of utilization of retrieved oocytes. Patients were divided into five groups depending on the number of retrieved oocytes. The mean fertilization rate of 57% was broadly similar amongst the groups but the proportion of retrieved oocytes that produced embryos of a quality suitable for transfer or cryopreservation (the cycle efficiency index) fell significantly with increase in the retrieved oocyte number. However, the pregnancy rate increased with the number of retrieved oocytes (13-38%). It is important to determine the point at which advantages of multifollicular development are outweighed by the potential for complications. Increased utilization of retrieved oocytes will decrease the need for production of a large number of oocytes.