Semen analysis

Background about male fertility and sperm problems

About 25% of all infertility is caused by a male problem, and in 40-50% of cases it is the main cause, or a contributing cause.

It is sometimes hard to know whether the male factor problem is the only cause, or just a contributing cause to the infertility. Part of the problem is that numbers are just numbers:

  • Men with very low sperm counts and low motility scores can sometimes have children
  • Some men with normal counts are infertile without using IVF and ICSI

What matters is not really how many or how fast they swim – but whether they can fertilize the female partner’s eggs. This is really a biochemical issue at the molecular level.

Therefore, looking at the little swimmers under the microscope is not always a perfect way of assessing the ability of the sperm to fertilize the female’s eggs.

Semen analysis

This is a very simple and important test and should be done early in the evaluation process. Sometimes the test should be done 2, or even 3 times to get an accurate reflection of the numbers and their variation over time.

The most important parameters in a semen analysis are:

  1. Concentration (often called “count“) – how many sperm are in each ml of semen?
  2. Motility – what percent of them are swimming forward?
  3. Morphology – what percent of them are normally shaped?

Cutoff values for normal vary somewhat, depending on the lab and the interpreter.

  • The World Health Organization’s 5th edition of “normal semen analysis” values are shown below
Semen Analysis Parameter Normal Values
Volume 1.5 ml or more
pH > or equal to 7.2
Sperm concentration 15,000,000/ml or more
Total motility 40% or more
Progressive motility 32% or more
Morphology 4% or more normal forms (Strict criteria)
Vitality 58% or more live
White blood cells Less than 1,000,000/ml

If a severe male factor defect is found, the amount of testing on the female is often reduced. Treatments, such as inseminations or in vitro fertilization can then be started more directly.

Semen analysis

Human sperm stained for morphology assessment – part of the male fertility testing workup

 

Further testing on the male with an abnormal semen analysis

In some cases we do hormone (blood) tests on men with abnormal semen analysis. This can (rarely) sometimes identify a reason for the abnormality. Occasionally, the problem will be treatable in the male.

Sperm function tests

Sperm penetration assay, also called the hamster egg test

The sperm is mixed with hamster eggs to see whether they penetrate the eggs. It is expensive and there are many false positives and also false negative results. Some men are better with the hamster than with his partner… etc. We do not do this test.

Human zona binding assay: In this test, sperm is mixed with pieces of human egg shells (zona pellucidas) to see how many will bind to the shells. There are a lot less false positives and false negative results as compared to the hamster egg test. However, human egg shells are not readily available – so it is not a practical test.

Sperm antibody testing

  • Sperm antibodies in the blood of men or women do not affect fertility
  • Antibodies on the head of the sperm can cause failure of fusion with the egg
  • Spontaneous pregnancy rates are higher in couples without these antibodies. However, fluctuations are seen even without therapy.
  • Also, since inseminations are used as treatment for both unexplained infertility and for sperm antibodies, some fertility specialists don’t find this test very useful.
  • Antibody testing can help determine whether sperm should be injected into the eggs if the couple does in vitro fertilization.