Understanding semen analysis

Why should I do a semen analysis test?

For most men, investigations into fertility problems will involve a semen analysis, where you are asked to produce a sample of sperm to be examined in the laboratory. By analysing factors including sperm quantity, motility (movement) and morphology (shape), we can give patients a better idea of their chances of achieving a pregnancy, and to recommend fertility treatments that will maximise their chances of success.

Do I have to abstain from sex before giving my semen sample?

It is important to abstain from sexual intercourse or masturbation for 2-7 days before giving your sample for the semen analysis test, as it can affect the result; a very short space of time between samples can decrease the sperm concentration, and leaving too long can affect the quality of the sperm. 

What do you do in the laboratory for a diagnostic semen analysis test?

When we do a diagnostic semen analysis test, we undertake measurements of various factors set out by the World Health Organisation (WHO, which has published reference limits for semen analysis*.

The first part of the test involves measuring the volume of semen produced. The average amount is about 3ml (slightly less than a teaspoonful) and should be more than 1.5ml. The sample is then tested for its acidity (pH, normally more than 7.2) and how runny it is (viscosity). After these initial tests, the sample is examined using a microscope.

The sperm concentration, or number, is calculated using a special microscope slide with a grid.  If the concentration is low (fewer than 15 million sperm per ml) it is classified as oligozoospermia and on the rare occasions that no sperm are seen it’s called azoospermia. 

The sperm are assessed for their motility (proportion of sperm moving) and progression (how fast they swim).  Poor motility (less than 39% swimming) is called asthenozoospermia. It is also noted whether any sperm are sticking together (agglutination) as this can affect their function.

A very important part of the semen analysis is sperm morphology, which involves examining the size and shape of at least 200 individual sperm to assess whether they look normal.  A normal-shaped sperm has an oval head and a tail about 10x the length of the head.  It also has part of its head covered by a cap called the acrosome, which is needed to fertilise an egg.  If less than 4% of sperm appear to have a normal shape, this is called teratozoospermia and can be a problem as the sperm may not be able to swim properly or attach to an egg.

What does a semen analysis result tell us?

A semen analysis result tells us if a man’s sample can be considered to be within the fertile range. However, it can’t tell us for sure if the sperm are actually able to fertilise eggs or not. Furthermore, it’s important to interpret a person’s semen analysis result in conjunction with their medical history.

There are further, more specialised tests which may give more information such as the SOS (Sperm Oxidative Stress) test, or testing for sperm DNA fragmentation levels. We will discuss further tests with you if we think they will be helpful.

Can I do anything to help improve my semen quality?

To date, relatively little is known about the causes of male factor infertility and there is no simple treatment that will definitely improve sperm quality.

It is important to maintain a healthy lifestyle, including normal body weight, healthy diet and regular exercise. Excessive alcohol consumption or smoking can be detrimental, so these should be cut down as much as possible.

Men should avoid wearing tight underclothing and taking long hot baths, so that the testicles can remain at the temperature nature intended (slightly cooler than normal body temperature).