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 × 10⁶/mL) and severe teratozoospermia (strict normal sperm morphology ≤5%). Sperm morphology correlates with sperm-ZP binding, and sperm concentration correlates with ZP-induced AR in infertile men with sperm concentrations >20 × 10⁶/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.