Analysis of factors associated with multinucleate formation in human IVF

This study was carried out to analyse if some of the sperm parameters assessed by computer-aided sperm analysis (CASA) are associated with multinucleate formation in human in vitro fertilization (IVF). In the present study, 137 IVF-embryo transfer (ET) treatment cycles in which pronucleate formation could be observed were enrolled. Sperm parameters after swim-up were assessed using CASA and strict criteria. Thirty-two (2.3%) of 1368 oocytes fertilized were judged as multinucleate formation, which occurred in 25 of 137 IVF-ET treatment cycles, giving the incidence of 18.2%. The factors associated with multinucleate formation were analysed. There were significant differences of the numbers of oocytes collected (13.9 vs. 9.2; p=0.028), fertilization rate (88.8% vs. 71.9%; p=0.011), curvilinear velocity (VCL) (162.7 microm/sec vs. 149.1 microm/sec; p=0.034), average path velocity (VAP) (100.3 microm/sec vs. 93.1 microm/sec; p=0.016), and amplitude of lateral head displacement (ALH) (5.9 microm vs. 5.3 microm; p=0.046) between 25 cycles with multipronucleate formation and 112 cycles with two pronucleate formations. However, there were no significant differences of women's age or the number of sperm inseminated between the two groups. These findings suggest that prediction of multinucleate formation in human IVF might be possible in patients when the number of oocytes collected is higher and sperm motility parameters after swim-up are faster. However, prevention of multinucleate formation seems to be unnecessary because a higher successful IVF-ET outcome is expected as a result of the excellent fertilization rate in these patients.