Infertility Tests of Sperm Function

By Rafat Abbasi, MD

Approximately one-half of all cases of infertility are due to the male. It is imperative that both partners get tested. The criteria for testing sperm were developed by the World Health Organization (WHO) to evaluate concentration, motility, and morphology.
The WHO classification has been replaced in most IVF units by more stringent testing. These criteria, developed by Dr. Kruger are referred to as the strict Kruger criteria.
Sperm has to undergo several changes for fertilization to occur. These include swimming out of the seminal fluid, being transported in the reproductive tract, maturing, binding to the egg, penetrating the zona, activating the egg, forming a pronucleus and fusing with the pronucleus of the egg. If this sequence fails, fertilization will not occur.
Tests of sperm function include
1. Hypo-osmotic swelling test This test assesses the durability of the sperm membrane. Several studies have linked this test with fertilization and implantation. Abnormalities of the nucleus and the plasma membrane can negatively impact the embryo.
2. Acrosome reaction test Only mature sperm can undergo an acrosome reaction. This reaction occurs at the zona pellucida of the egg and allows the sperm to penetrate the egg.
3. Hamster egg penetration assay This measures the sperms capacity to undergo changes (capacitation, penetration, decondensation) necessary for fertilization.
4. Hemizona assay This test also evaluates the fertilizing ability of the sperm by evaluating the binding of the sperm to the zona of the egg.
5. DNA fragmentation assay This technique allows the selection
of sperm free from significant DNA damage by utilizing a separation technique.
A semen analysis does not provide adequate information about the fertilizing potential of sperm. Sperm function testing is an important part of the investigation of the male.