Sperm Function Tests

The sperm mucus penetration test – this test checks if a man’s sperm can move through the cervical mucus. This test is not done very often because there are other fertility tests that give more information about the fertility problem.

ROS ( reactive oxygen species)

Reactive oxygen species (ROS) are an integral component of sperm developmental physiology, capacitation, and function. When the ROS levels exceed that of the antioxidant activity due to infection or inflammation, it can be associated with abnormalities of sperm development, function, and capacity to fertilize the egg.  ROS may be estimated in whole ejaculate using various chemiluminance methods or by semi-quantitative assays using oxidative indicators.

Hypo-osmotic swelling test (HOS TEST)

The hypoosmotic swelling (HOS) test evaluates the functional integrity of the sperm’s plasma membrane and also serves as a useful indicator of its fertility potential. The functional integrity can be demonstrated by allowing sperm to react in a hypoosmotic medium. The hypoosmotic swelling test presumes that only cells with intact membranes (live cells) will swell in hypotonic solutions. The results of the HOS test correlate closely with the hamster egg penetration test. Spermatozoa with intact membranes swell within 5 min in hypoosmotic medium, and all flagellar shapes are stabilized in 30 min.

Zona binding assay

As binding of the sperm to the zona pellucida is essential for fertilization, a test to assess the sperm’s ability to bind to the zona has the potential to predict a defect in sperm function that may be the cause of infertility. Because of species specificity, human oocytes are required to test for zona binding ability. This test uses non-living oocytes from surgically removed ovarian tissue ( oophorectomy ), so that the ethical problems of fertilization are avoided. The oocyte is halved and the patient’s sample is tested on one half  and a fertile sample on the other, to provide a control. The score for the assay, the hemizona index (HZ) is the number of test sperm bound, to zona, expressed as a percentage of the control sperm. An HZ of less than 30 percent is considered abnormal and is associated with a decreased probability of fertilization.

Anti-Sperm Antibodies

An anti sperm antibody test looks for special proteins (antibodies) that fight against a man’s sperm in blood, vaginal fluids, or semen. The test uses a sample of sperm and adds a substance that binds only to affected sperm.

Semen can cause an immune system response in either the man’s or woman’s body. The antibodies can damage or kill sperm. If a high number of sperm antibodies come into contact with a man’s sperm, it may be hard for the sperm to fertilize an egg. The couple has a hard time becoming pregnant. This is called immunologic infertility.

A man can make sperm antibodies when his sperm come into contact with his immune system. This can happen when the testicles are injured or after surgeries (such as a biopsyor vasectomy) or after a prostate gland infection. The testicles normally keep the sperm away from the rest of the body and the immune system.

A woman can have an allergic reaction to her partner’s semen and make sperm antibodies. This kind of immune response is not fully understood but may affect fertility. This is a rare cause of infertility.

Sperm penetration assay

The sperm penetration assay, or zona-free hamster oocyte penetration assay is utilized to measure the ability of sperm to  fuse with the egg membrane and be able to fertilise it. The test is scored by calculation of the percentage of oocytes that are penetrated  by sperm or the average number of sperm penetrations per ovum.a normal test indicates a penetration of 10-20% and lower values indicate a poor results in IVF. It has been used to identify those couples who will have a high likelihood of success with in vitro fertilization.

DFI (DNA Fragmentation Index)

This test provides information about the genetic constitution of the sperm. Men with abnormal sperm parameters may have a high DNA fragmentation even though this can be found in men with normal semen parameters who are diagnosed with unexplained infertility.

High DNA fragmentation is associated with poor embryo quality and high rate of miscarriages.

Indications for DNA fragmentation testing:

• Unexplained or persistent infertility
• Failure to conceive after 5–6 intrauterine insemination (IUI) cycles despite good count and motility
• Low fertilization rates or poor embryo quality in IVF cycles
• IR failure after IVF
• Recurrent miscarriage
• Prolonged stay in an environment that exposes to reproductive toxins
• Abnormal semen analysis
• Advancing male age (>45 years).