Cap-Score™ Sperm Test

Semen Analysis: The Original Sperm Test

When a couple sees a fertility specialist, they may notice something peculiar. The doctor recommends lots of tests for the woman but only one test – the semen analysis – for men. The semen analysis, which involves looking at sperm under a microscope, was the original sperm test.

The semen analysis was first performed in 1677 by Anton van Leeuwenhoek who happened to make a better lens for microscopes and so was first able to see these small cells. Years later, scientists were able to determine that most men with normal fertility had large number of moving sperm and sperm with a normal shape. More recently, software was developed that allowed computer assisted semen analysis

Development of newer sperm tests

The main problem with the semen analysis is that it was not a very accurate predictor of male fertility. Over the last few decades, there have been numerous attempts to develop a sperm test that would predict male fertility more accurately. Unfortunately, there was not much success – until recently.  A new sperm test, known as the Cap-Score™ is the first test that actually measures a key function of sperm called capacitation.


Ejaculated sperm are not ready to fertilize an egg when they enter the vagina. In response to the dilution of semen in the vagina, the levels of a protein called FPP (fertilization promoting peptide) start dropping. This results in the sperm starting to undergo several changes, which are collectively known as capacitation.

Sperm capacitation

During capacitation, the head of the sperm sheds some proteins and other molecules from its surface, this allows the mineral calcium enters the sperm more rapidly which results in increased energy production and then the sperm tail starts to beat more vigorously (hyperactivation). This may help the sperm power its way through the cells that surround the egg.

Finally, there is a small sac of enzymes at the top of the sperm head called the acrosome. During capacitation, the acrosome starts to become more unstable. These enzymes will be needed to dissolve the hard shell that surrounds the egg.

Unless a sperm undergoes capacitation, it will not be able to fertilize an egg.


As you might have guessed, some men may make sperm that are unable to undergo capacitation or have only a small percentage of the sperm that do so. The Cap-Score™ is a test that was developed to determine the percentage of sperm that undergoes capacitation in a certain amount of time.

By looking at men with normal fertility, scientists were able to determine that the average fertile man has about 35% of his sperm that will undergo capacitation (Cap-Score™ of 35%). Men with a low Cap-Score™ – 27% or less – are likely to have fertility problems, even if there are lots of fast moving sperm. Data now shows that the the higher the percentage of sperm that undergo capacitation, the higher the probability for pregnancy.

Sperm Test - Cap-score

What do I do if I have a low Cap-Score™?

Currently, we do not know of a way to improve a man’s ability to have his sperm undergo capacitation. The current recommendation for these couples is to not waste time and money with treatments that require sperm capacitation such as intercourse or intrauterine insemination (IUI). Data shows that even with several cycles of IUI, couples with an abnormal test have a lower chance for pregnancy. Instead, these couples should consider moving directly to IVF where the sperm can be injected directly into an egg to fertilize it. This is called ICSI. This will completely bypass a problem with capacitation.

Where can I get the Cap-Score™ Sperm Function Test?

You can do all of your sperm testing here at IVF1. Many of them are done here, others like the Cap Score, will be sent to their lab for analysis.