Clinical application of sperm-oocyte interaction tests in in vitro fertilization--embryo transfer and intracytoplasmic sperm injection programs.

OBJECTIVE: To review the clinical value of sperm-oocyte interaction tests for the diagnosis and management of infertility by standard IVF or intracytoplasmic sperm injection (ICSI).
DESIGN: Review of recent publications on relationships among sperm-oocyte interaction tests, sperm characteristics, and results of IVF and determination of frequency of defective sperm-oocyte interaction in infertile men. MAIN OUTCOME MEASURE(S): Fertilization rates with IVF, sperm characteristics, sperm-zona pellucida (ZP) binding, ZP-induced acrosome reaction (AR), and sperm-ZP penetration. RESULT(S): Sperm defects associated with low sperm-ZP binding or impaired ZP-induced AR and sperm-ZP penetration are the major causes of failure of fertilization when all or most oocytes from a couple do not fertilize in standard IVF. There is a high frequency of defective sperm-ZP interaction in men with oligozoospermia (<20 x 10(6)/mL) and severe teratozoospermia (strict normal sperm morphology < or =5%). Sperm morphology correlates with sperm-ZP binding, and sperm concentration correlates with ZP-induced AR in infertile men with sperm concentrations >20 x 10(6)/mL. Defective ZP-induced AR may cause infertility in up to 25% men with idiopathic infertility. These patients require ICSI despite the normal standard semen analyses. CONCLUSION(S): Sperm-oocyte interaction tests are useful for diagnosis of subtle sperm defects that cause infertility in men without severe abnormalities of semen analysis. Pre-IVF diagnosis of these sperm defects will assist in the clinical assignment of patients to treatment with either standard IVF or ICSI.