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Sperm Penetration Tests

Test Overview

Sperm penetration tests check to see if sperm can move through cervical mucus or join with (fertilize) an egg. These tests may be done when you're having trouble getting pregnant (infertility).

There are different sperm penetration tests.

  • The sperm mucus penetration test checks if 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.
  • The sperm penetration assay checks if sperm can join with an egg. (This is also called the hamster zona-free ovum test or hamster test.) Sperm are mixed with hamster eggs in a laboratory. The number of sperm that penetrate the egg is measured. This test is not done often. But it may be done at special fertility centers that do in vitro fertilization.

Why It Is Done

Sperm penetration tests may be done:

  • When other tests have not found a cause for infertility.
  • To see how the sperm function when a semen analysis test has shown some problems. Problems could include the sperm moving slowly or looking abnormal.
  • To test sperm before doing in vitro fertilization.

How To Prepare

Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results will mean.

Sperm mucus penetration test

A cervical mucus sample needs to be collected during ovulation. Follow your doctor's instructions for checking the level of luteinizing hormone (LH) in your urine. If your test shows that you are ovulating, call for a doctor's visit for the next day.

The semen sample is collected after the cervical mucus sample is taken. You should not release your sperm (ejaculate) for 2 to 5 days (but no longer than 1 week) before the test.

Sperm penetration assay (SPA)

The SPA only requires a semen sample to be taken.

It is important that you do not release your sperm (ejaculate) for 2 to 5 days (but no longer than 1 week) before the test.

How It Is Done

Sperm mucus penetration test

For the sperm mucus penetration test, a sample of cervical mucus will be collected during a pelvic exam. In the lab, the semen sample is added to the mucus in a tube. After 90 minutes, the distance the sperm have moved is measured.

Sperm penetration assay (SPA)

For the SPA, sperm from the semen sample are mixed with hamster eggs in a lab. The number of sperm that can penetrate an egg is measured.

How It Feels

Cervical mucus sample

You may feel some pressure or mild discomfort when the speculum is placed into your vagina. The speculum opens the vagina a little bit. This allows your doctor to look at the inside of the vagina and the cervix. The speculum may be warmed with water or lubricated with a vaginal lubricant (such as K-Y Jelly).

Semen sample

Collecting a semen sample does not cause any discomfort.


There is very little chance of a problem from collecting a sample of vaginal fluid or from collecting a semen sample.


Sperm mucus penetration test

This test uses donor sperm and the male partner's sperm. Both sperm samples are added to a sample of the woman's cervical mucus. Donor cervical mucus may also be used with the woman's cervical mucus.

There may be a problem with the partner's sperm if:

  • The donor's sperm penetrates the mucus, but the partner's sperm does not.
  • The partner's sperm does not penetrate the woman's or the donor's cervical mucus.

There may be a problem with the woman's mucus if neither the partner's nor the donor's sperm penetrate the cervical mucus.

Sperm mucus penetration testfootnote 1


Sperm penetrate the cervical mucus and move through it easily.


Sperm can't penetrate the cervical mucus, or they clump together in the mucus. Clumping may mean that the woman or man has formed antibodies against the sperm. If the sperm antibodies are from the man's body, clumping may also be seen in his semen analysis.

Sperm penetration assay (SPA)

Results are based on the number of sperm that can penetrate an egg. This can vary from lab to lab. Talk with your doctor to find out if your results are normal.

Sperm penetration assay (SPA)


Sperm penetrate the hamster egg.


Sperm can't penetrate the hamster egg.



  1. Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.


Current as of: February 11, 2021

Author: Healthwise Staff

Medical Review:

Sarah Marshall MD - Family Medicine

Adam Husney MD - Family Medicine

Kathleen Romito MD - Family Medicine

Femi Olatunbosun MB, FRCSC - Obstetrics and Gynecology

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