additional sperm tests

Additional sperm tests can be carried out to investigate the interaction between the female partner’s cervical mucus and the male’s sperm more closely than with the post-coital test. In addition the fertilising capacity of the sperm can be investigated.

In normal fertilisation, the sperm binds to the outer layer of one egg (ovum), and one sperm cell breaks through or penetrates the barrier around the ovum leading to fertilisation. In some cases of male infertility, the sperm may be unable to bind to the ovum and penetrate it. Although the fertilisation process is not fully understoood, partial aspects of the underlying processes can be studied in the hemizona or hamster ovum penetration test discussed below. The value of these fertilisation tests is however debatable and they are, at present, rarely used.

sperm penetration and migration test (SPM)
the hemizona test for sperm binding
the hamster ovum penetration test
semen survival test (SST)
immunobead test (IBT)

sperm penetration and migration test (SPM)

The post-coital test is used to test the ability of the sperm to survive in the cervical mucous. If negative it can suggest problems regarding the quality of sperm or cervical mucous. A SPM test may be carried out in if two or more post-coital test come back negative, to determine whether a mucous defect or a sperm cell defect is the cause of the problem. The interaction between sperm and cervical mucous is tested even further in the laboratory as part of this process. In addition, the mucous and the sperm cells are tested with donor material.

the hemizona test for sperm binding

The hemizona test assesses the ability of the sperm to bind to an ovum. A non-living (non-viable) donor egg cell is divided under the microscope. One half of the outer layer is mixed with donor sperm of proven fertility to serve as a control or comparison. The other half is mixed with the patient’s sperm. The number of sperm cells that bind (adhere) to each half is compared. Very low binding of the patient’s sperm can indicate that the sperm has a functioning problem.

the hamster ovum penetration test

Sometimes doctors perform an experiment to gauge if a man’s sperm is likely to penetrate a woman’s ovum. To do this, the sperm is tested with a specially prepared hamster ovum (the male sperm does not truly ‘fertilise’ the hamster ovum). This is used to measure the ability of the sperm to both bind to an ovum and penetrate it. If the test situation results in good penetration, there is a good chance that the sperm is capable of fertilising a human ovum.

Penetration tests do not have absolute predictive value - efficient sperm can fail the penetration test, just as inefficient sperm can pass it. Therefore penetration tests are rarely used any more.

semen survival test (SST)

If the man’s sperm quality is very poor, an extra sperm test - SST - may sometimes be carried out in the IVF laboratory to determine whether it is of sufficient quality to begin a regular IVF procedure, or whether it would be advisable to go straight to ICSI.

For a regular IVF procedure, it must be possible to obtain sufficiently mobile sperm in order for them to be able to fertilise the ova in the laboratory. In an ICSI procedure, one moving sperm cell is selected for every ovum collected; it is then injected directly inside the ovum. This method therefore allows embryos to be obtained even with very few moving sperm cells.

immunobead test (IBT)

Antibodies are an important weapon that help the body to fight infections. If the body recognises ‘foreign’ substances, it tries to build up immunity or antibodies against the substance. Yet in the case of anti-sperm antibodies, the body recognises the sperm as foreign and manufactures antibodies to attack the sperm. The resultant antibodies hinder the movement of the sperm as it attempts to reach the egg (ovum) through the cervical mucous preventing the normal reproductive process. The development of these antibodies can be caused by infections or other factors.

In order to check for the presence of anti-sperm antibodies, doctors perform an immunobead test (IBT). Nowadays, this test is only carried out sporadically.

An IBT can reveal different types of anti-sperm antibodies in various biological samples including the woman’s blood, cervical mucous and the sperm cells themselves. The test can show the severity of the antibodies and which part of the sperm they are specifically attacking. An IBT can also determine from a blood sample whether the antibodies come from the circulation or from around the sex organs.

To find antibodies, blood is taken from the woman, cultured with a sperm sample and studied under a microscope in the laboratory. A man’s sperm can be tested for antibodies directly.

If anti-sperm antibodies are present, they can be treated in various ways. One of those ways is to correct the underlying defect that is causing the problem. Some women are treated with prednisone, a steroid that can help to reduce the production of antibodies. Intra-uterine inseminations with washed sperm can also be carried out.