Anti Sperm Antibody (ASAB) Test

The antisperm antibody test is a blood test that detects antisperm antibodies (ASAs), which are proteins produced by the immune system that mistakenly react against sperm.

Normally, sperm are protected from the immune system by a natural barrier inside the testes called the blood-testis barrier. Damage to this barrier due to injury, infection, surgery, vasectomy (an operation that prevents sperm from being released), or varicocele (enlarged veins in the scrotum) may expose sperm to the immune system, leading to the production of ASAs. These antibodies can reduce sperm movement, cause them to stick together, or interfere with their ability to fertilise an egg.

The antisperm antibody (ASAB) test helps doctors investigate immune-related infertility in both men and women. It is usually recommended when infertility remains unexplained after routine fertility tests.

The ASAB test is recommended when a couple has difficulty conceiving and routine fertility tests do not reveal the reason for infertility, particularly if immunological infertility is suspected. It may also be advised if a semen analysis shows low sperm movement, sperm agglutination (clumping), or other signs that suggest the presence of ASAs.

Symptoms or situations where this test may be recommended include the following:

• Difficulty conceiving despite regular unprotected intercourse for one year or more.
• Reduced sperm movement or sperm agglutination as detected on semen analysis.
• Unexplained infertility after routine fertility investigations.
• Repeated failure of assisted reproductive methods, such as intrauterine insemination (IUI).
• History of testicular injury, surgery, a vasectomy, or surgery to reverse vasectomy.
• History of infections or inflammation affecting the male reproductive tract.
• Presence of varicocele in men undergoing infertility evaluation.

People who may need this test include:

• Men with unexplained infertility.
• Men with abnormal semen analysis results, especially reduced sperm movement or sperm clumping.
• Men with a history of testicular trauma, surgery, vasectomy, or vasectomy reversal.
• Couples undergoing infertility investigations before assisted reproductive treatment.

The ASAB test is not a routine screening test. It is usually performed once as part of an infertility evaluation when immune-related infertility is suspected.Repeat testing is generally not required unless recommended by a fertility specialist to support diagnosis or treatment planning.

The antisperm antibody test helps identify immune system causes of infertility. A positive result indicates that ASAs are present, which can affect sperm function and reduce the chances of getting pregnant.

The test may help detect or support the diagnosis of the following conditions:

• Immune-related infertility: In this condition, the body's immune system mistakenly attacks sperm, producing antibodies that target them. These antibodies can slow sperm movement, cause them to stick together, or prevent them from fertilising the egg.
• Male infertility associated with varicocele: Varicocele is the swelling of veins in the scrotum. It may damage the protective layer around the testes, causing the immune system to make ASAs.
• Infertility following vasectomy or vasectomy reversal: ASAs commonly develop after vasectomy and may persist after vasectomy reversal, affecting fertility in some men.
• Infertility associated with testicular injury or surgery: Injury or surgery involving the testes can expose sperm to the immune system, leading to the production of ASAs.
• Unexplained infertility: In some couples, infertility occurs despite normal findings on routine investigations. The antisperm antibody test may help determine whether immune-related factors are contributing to infertility.

What to Expect Before the Antisperm Antibody Test?

• No fasting is required for a standalone Antisperm Antibody test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise Antisperm antibody levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection?

• A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Antisperm Antibody Test?

• A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

The test includes the following parameter:

• Antisperm antibody (ASAB): The presence of these antibodies may interfere with sperm movement, function, or ability to fertilise an egg, thereby contributing to infertility.

The table below shows the reference range of antisperm antibody. A negative result is considered normal.

The results of the ASAB test help determine whether antisperm antibodies are present in the blood. The findings should always be interpreted along with the patient's symptoms, medical history, semen analysis, and other fertility tests.

The antisperm antibody test is generally safe because it only requires a blood sample. However, like all medical tests, it has certain risks and limitations.

Potential Risks and Complications

• Mild pain or discomfort at the site where the blood sample is collected.
• Minor bruising or slight bleeding at the puncture site.
• Rarely, dizziness, fainting, or infection may occur after blood collection.

Understanding the Antisperm Antibody (ASAB) Test Limitations

• A positive antisperm antibody test does not necessarily mean that a person is infertile. Some people with ASAs can still conceive naturally.
• A negative test result does not completely rule out infertility, as many other male and female factors can affect fertility.
• The test cannot identify the exact cause of infertility and should be interpreted together with semen analysis results, medical history, physical examination, and other fertility investigations.

Depending on the results of the antisperm antibody test, your doctor may recommend additional tests to identify the cause of infertility and plan further treatment.

• Semen analysis: Evaluates sperm count, movement, shape, and other characteristics to assess male fertility.
• Mixed antiglobulin reaction (MAR) test: Detects ASAs attached directly to moving sperm and helps determine their effect on sperm function.
• Immunobead test (IBT): Detects where the ASAs are attached to the sperm, including the head, midpiece, or tail. This information can help assess their impact on fertilisation.
• Sperm DNA fragmentation test: Assesses damage to the genetic material within sperm, which may contribute to male infertility and poor reproductive outcomes.