Where sperm abnormalities cause infertility

 

MEN'S HEALTH MATTERS:When couples find it hard to conceive men are often checked first because tests for women are trickier, writes THOMAS LYNCH.

Q I am 31 and my wife and I have been trying to have a baby for the last two years but have been unsuccessful. My doctor has examined me and says that everything is normal but that I should have my semen analysed. Can you explain what this entails and what do they look for when semen is examined in the laboratory?

AWhen testing a couple for infertility, the man’s semen is generally tested first because tests for women are far more complicated, invasive and expensive. Studies show that 40 per cent of infertility is because of a medical problem with the man.

A fresh semen sample is obtained after sexual abstinence for about two to four days. The sample is captured into a clean, wide-mouthed bottle and if the sample spills or leaks out, the test is invalid and needs to be repeated. The semen sample must be kept at room (or body) temperature while it is being delivered directly to the laboratory. A semen analysis to determine fertility should be performed on a minimum of two samples at least seven days apart

It requires a lot of skill to perform a semen analysis accurately and it is very important that it is carried out in a laboratory with the necessary expertise. An inaccurate report can be very misleading – leading to confusion and angst for both patient and doctor.

In the laboratory the volume of the ejaculate is estimated, which is normally about 2ml to 6ml and abnormalities with the volume are not very common. A very low volume will cause problems, because too little semen may mean that the sperm find it difficult to reach the cervix. A very high volume, surprisingly, will also cause problems, because this dilutes the total sperms present, decreasing their concentration.

The most important test is the visual examination of the sample under the microscope. Sperm are microscopic creatures which look like tiny tadpoles swimming about at a frantic pace. Each sperm has a head, which contains the genetic material of the father in its nucleus; and a tail which lashes back and forth to propel the sperm along. The mid-piece of the sperm contains mitochondria, or the power house, which provides the energy for sperm motion.

After the volume has been measured the next step is to estimate the sperm concentration. This is measured in millions of sperm per millilitre of semen. Normal is greater than or equal to 20 million per millilitre (and more than 80 million sperm in one ejaculation). The fewer sperm a sample has, the less chance of getting a woman pregnant.

Motility is the percentage of moving sperm in a sample and about 70 per cent of the sperm should be mobile with a very active forward progression. The more slowly moving or immobile sperm in a sample, the less likely that a pregnancy will occur. The progression of the sperm is rated on a basis from zero (no motion) to three or higher for sperm that move in a straight line with good speed. If less than half of the sperm are motile, a stain is used to identify the percentage of dead sperm. This is called a sperm viability test.

Morphology analysis is the study of the size, shape, and appearance of the sperm cells. It evaluates the structure of about 200 sperm. The more abnormal sperm that are present, the lower the likelihood of fertility.

The pH of the semen is also measured and it is normally alkaline. An alkaline pH protects the sperms from the acidity of vaginal fluid. An acidic pH suggests problems with seminal vesicle function – either absence of the seminal vesicles, or an ejaculatory duct obstruction. Fructose, a sugar, is produced by the seminal vesicles and provides energy for sperm motility. Its absence suggests a block in the male reproductive tract at the level of the ejaculatory duct.

Several factors can affect the sperm count and other semen analysis values. A man may have a lower sperm count if he has physical damage to the testicles, has had radiation treatment on his testicles, or has taken certain drugs (such as azathioprine or cimetidine). A man with a higher level of oestrogens may have lower sperm counts. Alcohol, many recreational and prescription drugs and tobacco may also affect counts. Some causes of male infertility are extremely high fever, failure of the testicles, obstruction of the tubes that carry semen to the penis, and a less than normal amount of sperm in the sample (oligospermia).

In summary the normal volume varies from two to five millilitres per ejaculation, the sperm count varies from 20 to 100 million sperm per millilitre and at least 60 per cent of the sperm should have a normal shape and show normal forward movement .


This column is edited by Thomas Lynch, consultant urological surgeon, St. James’s Hospital, Dublin.

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