Objectives: The aim of the study was to compare the outcomes of intracytoplasmic sperm injection/embryo transfer (ICSI/ET) between two IVF centers with similar pregnancy rates and embryo transfer policy but with two different approaches to good-prognosis patients who intentionally chose to limit the number of oocytes used for ICSI.
Material and methods: It was a retrospective two-center comparative study A total of 218 patients after successful retrieval of >10 mature oocytes following ovarian hyperstimulation were included in the study The number of fertilized oocytes used during ICSI/ET was limited to 6 and 10 in 108 and 110 patients of the Centre for Reproductive Medicine KRIOBANK and VitroLive Fertility Clinic, respectively
Results: No significant differences in the implantation rate (29.93% vs. 29.54%; p=0.94) and ongoing pregnancy rate (39.81% vs. 45.45%, p=0.40) were observed between patients who electively fertilized 6 as compared to 10 oocytes, respectively However in patients who deliberately limited the number of fertilized oocytes to 6 the following were observed: i) significantly fewer embryos available for ET (2.89 ± 1.23 vs. 3.77 ± 1.48, p<0.0 1); ii) considerably lower number of frozen embryos per cycle (1.05 ± 1.30 vs. 2.00 ± 1.67, p<0.01), and iii) lower rates of cycles with embryo cryopreservation (4 7.22% vs. 72.72%, p<0.01) as compared to patients with 10 fertilized oocytes.
Conclusions: Elective fertilization of 6 vs. 10 oocytes does not adversely affect fresh ICSI/ET outcome in normal-responding patients. Restricted number of oocytes used for ICSI/ET may be a favorable alternative for couples who do not wish to cryopreserve surplus human embryos.