Semen Analysis

How is it used?

A semen analysis is used to determine whether a man might be infertile (unable to get a woman pregnant) or subfertile (less likely to make a woman pregnant compared to the average fertile men). One in 7 couples suffers from subfertility (inability to conceive after two years of having regular unprotected sexual intercourse). Male factors are implicated in about 30% of the time and combined male and female factors in about 20% of the time. The semen analysis has many parts and tests many aspects of the seminal fluid and sperm. An up to date semen analysis (one performed within the last year) is needed for assessment of the couple’s fertility status. If the initial semen analysis is normal, there is no need to repeat the test. However, a swim-up test may be needed for couples undergoing intrauterine insemination (IUI), in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). If the initial semen analysis is abnormal, a repeat test may be requested after one to 10 weeks depending on the result of the initial test. This is because the sperm count and semen consistency will vary from day to day and some conditions can temporarily affect sperm levels.

The semen analysis also can be used to count sperm after a man has a vasectomy. If there are still sperm present in the semen, whether alive or apparently dead, the man and his partner will have to take precautions so that the woman does not become pregnant. He will have to return for one or more sperm counts until sperm are no longer present in his sample(s).

What does the test result mean?

The typical volume of semen collected is around one-half to one teaspoonful (2-6 millilitres) of fluid. Less semen would indicate fewer total sperm, which may affect fertility. More semen indicates too much fluid, which may dilute the concentration of sperm. The semen should initially be thick and then liquefy within 10 to 30 minutes. If this does not occur, then it may impede sperm movement.

Sperm concentration (also called sperm density) is measured in millions of sperm per millilitre (ml) of semen. Normal is 20 million or more sperm per ml, with a total of 80 million or more sperm in one ejaculation. Fewer sperm and/or a lower sperm concentration may impair fertility. Following a vasectomy, the goal is to have no sperm detected in the semen sample.

Motility is the percentage of moving sperm in a sample and an evaluation of their rate and direction of travel. At least 50% should be motile one hour after ejaculation, and they should be moving forward in a straight line with good speed. The progression of the sperm is rated on a basis from zero (no motion) to 4, with 3-4 representing good motility. Morphology analysis is the study of the size, shape, and appearance of the sperm cells. The analysis evaluates the structure of 200 sperm, and any defects are noted. The more abnormal sperm that are present, the lower the likelihood of fertility. Abnormal forms may include defective heads, middles, tails, and immature forms. The cut off percentage of normal morphology varies between different laboratories. In our laboratory, it is currently 40%, which means at least 40% of the sperm should have a normal morphology. Semen pH should be between 7.2 and 7.8, and there should be less than 2000 white blood cells per ml.

Is there anything else I should know?

When a doctor is evaluating a man’s fertility, each aspect of the semen analysis is considered, as well as the findings as a whole. Each part of the semen analysis either contributes to fertility or lessens it, but the results do not necessarily predict the eventual outcome. Couples with poor results may still conceive, with or without assistance, and those with apparently good results may experience difficulties.