Intracytoplasmic morphologically selected sperm injection improves development and quality of preimplantation embryos in teratozoospermia patients

Abstract

This prospective randomized study investigated whether intracytoplasmic sperm injection (ICSI) outcome can be improved with sperm preselection under ×6000 magnification and intracytoplasmic morphologically selected sperm injection (IMSI) in patients with teratozoospermia and characterized embryo development and quality regarding sperm morphology and presence of head vacuoles. Couples with isolated teratozoospermia were divided into two groups: IMSI group (n=52) and ICSI group (n=70) and fertilization, blastocyst and clinical pregnancy rates were compared. Oocytes from 30 randomly chosen patients from the IMSI group were injected with spermatozoa that had been previously classified under ×6000 magnification into four classes according to the number and size of vacuoles in the head and then cultured separately. Pronuclear morphology, embryo development and blastomere viability were estimated to investigate the influence of sperm morphology, especially vacuoles, on embryo developmental capacity. A significantly higher clinical pregnancy rate was achieved in the IMSI group compared with the ICSI group (48% versus 24%, P<0.05). Fertilization with spermatozoa without head vacuoles yielded higher number of morphologically normal zygotes, higher blastocyst rate and smaller proportion of arrested embryos than spermatozoa with vacuoles and other head defects. IMSI is a method of choice in patients with teratozoospermia.Data suggests that morphologically abnormal spermatozoa and/or spermatozoa with fragmented DNA have a negative impact on fertilization and embryo quality, even when intracytoplasmic sperm injection (ICSI) is performed. The aim of our prospective randomized study was to see if an ICSI outcome can be improved with sperm pre-selection under ×6000 magnification (intracytoplasmic morphologically selected sperm injection, IMSI) in patients with teratozoospermia and to characterize embryo development and quality regarding the sperm morphology and the presence of head vacuoles. Couples with isolated teratozoospermia were divided into two groups: IMSI group (n=52) and ICSI group (n=70). Fertilization, blastocyst and pregnancy rates were compared between the two groups. Oocytes from 30 randomly chosen patients from the IMSI group were injected with spermatozoa that had been previously classified under ×6000 magnification into four classes according to the number and size of vacuoles in the head and then cultured separately. Pronuclear morphology, embryo development and blastomere viability were estimated in order to see the influence of sperm morphology, especially vacuoles, on embryo developmental capacity. A statistically significant higher pregnancy rate was achieved in the IMSI group compared with the ICSI group (48% versus 24%, P<0.05). Fertilization with spermatozoa without head vacuoles yielded a higher number of morphologically normal zygotes, higher blastocyst rate and smaller proportion of arrested embryos than spermatozoa with vacuoles and other head defects. This means that IMSI is a method of choice in patients with teratozoospermia.