Does the presence of nuclear vacuoles in human sperm selected for ICSI affect pregnancy outcome?

BACKGROUND: To verify whether or not microinjection of sperm with a normal nuclear shape but large vacuoles affects IVF–ICSI pregnancy outcome. METHODS: A comparative study testing IVF outcome parameters of IVF–ICSI, based on morphological selection of spermatozoa with normal nuclei against those based on microinjection of sperm with a normal nuclear shape but large vacuoles. An experimental group, including 28 IVF–ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a normal nuclear shape but large vacuoles were transferred, was matched with a control group, including 28 IVF–ICSI cycles, where only embryos obtained from microinjection of spermatozoa with a strictly defined morphologically normal nuclear shape and content were transferred. The main outcome was IVF–ICSI pregnancy rate. RESULTS: The experimental group exhibited a significantly lower pregnancy rate per cycle and significantly higher abortion rate per pregnancy compared to the control group (18 versus 50%, and 80 versus 7%, respectively, P = 0.01). CONCLUSION: Microinjection of vacuolated sperm appears to reduce the pregnancy rate and appears to be associated with early abortion.