What causes low or variable sperm counts?

August 22, 2010Carole 2 Comments »

The results of a semen analysis can vary from test to test. Sometimes this variation is clinically significant, sometimes it’s not. That’s why most doctors will order at least two semen analyses to corroborate the first result.

What is clinical significance? A semen analysis is a estimate of the amount (sperm concentration) of sperm in the ejaculate, the quality and quantity of motion (motility) that sperm have and what percent of sperm have the expected shape to be classified as normal. This sperm count estimate does not have to accurate to the last sperm but it must at least be accurate and reproducible enough so that good clinical judgments can be made from the estimate. For instance, if your doctor is trying to decide whether to do ICSI, it won’t matter whether the patient has 20 million sperm per ml or 100 million sperm per ml, because assuming the sperm are alive (or viable), either answer would rule out the need for ICSI, so even a 5 fold error would not have clinical significance.

At the other end of the spectrum when counts are abnormally low, errors in the estimate would make a big difference in whether IUI, IVF or ICSI would be advised- so these errors would be clinically significant. Mistakes at the low end are more likely to be clinically significant. Andrologists argue about the best way to perform a semen analysis. For instance, here they debate about whether two samples should be counted from each ejaculate to detect pipeting errors and the merits and problems with different kinds of counting chambers and manual versus machine counts.

Computer assisted semen analysis  or CASA is sometimes assumed to be more accurate than human counters but CASA counts also need to be validated. We had a patient who came to us for a semen analysis after he had been to his urologist and told his CASA count was not just fine, but exceptional. We found much lower sperm numbers doing either a manual or a CASA count- which did not make the couple happy! We did note that our patient had a lot of sperm-sized debris in his sample, and when we adjusted the filters to count the debris as sperm, we could duplicate the high counts that the other lab reported. It turns out they had just gotten a CASA but had calibrated it incorrectly or not at all so that the debris was counted and added to the sperm numbers, artificially inflating the count. They weren’t experienced enough to realize that a clean debris-free counting field was necessary for machine counts. A technician performing a manual count could not mistake debris for sperm. This mistake was clinically significant because the couple needed IVF with ICSI and had been wasting their time with IUI’s based on this erroneous count.

The lab where the semen analysis was done can affect the result. When we received lab results from clinical labs not associated with fertility programs, we always wanted to repeat the analysis ourselves. In a clinical lab, there is a hierarchy of tasks and specialties and semen analysis ranks near the bottom of tests. After all, semen analysis is never a stat test- no one’s life depends on the result- so sometimes specimens sit around until the other stat tests are performed. It’s fine for the sample to sit around for awhile if it is being counted post-vasectomy to verify that no sperm are present, but if you want to see what the motility and viable (living) concentration is, leaving it sit at room temperature or in the fridge for several hours will degrade the quality of the sperm. Make every effort to collect the sample in the lab, not at home, to prevent degradation of the sample in transit to the lab. Ideally, you should have the semen analysis performed at the same fertility clinic that will use it to help you conceive. Your fertility lab is most highly vested in getting an accurate result because they will be held accountable for working with it.

Sometimes counts are really low the first time, but increase at a later semen analysis. What can cause this?

Losing part of the ejaculate. Nervousness and anxiety about producing a sample in a clinical situation can cause part of the sample to miss the cup. Men aren’t always forthcoming about this as you might imagine. The test form will often ask if the complete sample was collected so that if the count is really low and some of the sample was lost, the physician can order a second analysis before making any clinical judgements based on an incomplete sample.

Sometimes sperm counts decline over time. What can cause this?

Vasectomy reversal failure. Sometimes when a vasectomy is reversed and the tubes put back together, the inner open part of the tube scars up and closes down over time, letting fewer and fewer sperm through and ultimately, closing off completely. Up to 12% of men will experience a late obstruction within 14 months of the vasectomy reversal. This loss of an open tube may show as a declining trend in sperm count over a period of weeks or months.

Issues that affect testicular health can cause problems with sperm count or quality. Your doctor will probably send you to be checked out by your urologist to rule out testicular cancer or other problems (cysts, varicoceles,  infection etc.) that can interfere with sperm production and lower sperm count over time. There are also a large number of environmental factors such as high scrotal temperature, exposure to chemicals, pesticides, radiation, and chemotherapy which can suppress sperm production.

Seasonal differences. Believe it or not, even humans have some cyclical variation in sperm counts even though humans aren’t considered to be seasonal breeders. Late winter or early spring when sperm counts are highest are apparently the seasons for love (or at least reproduction) in humans.

Abstinence. Prolonged periods of abstinence from ejaculation can result in decreased sperm quality. No abstinence or very short period of abstinence ( a day or less) can reduce the count. Optimally, patients are asked to abstain from ejaculation for two to five days before producing a test sample.

Fevers. Having an illness with fever for several days can affect sperm production and sperm quality. The longer the fever persists, the greater the negative effect. Because sperm production takes 70 days to make a “batch” of sperm, the impact of fevers may not be recognized for a couple of months.

Lifestyle factors. Obesity, smoking, some prescribed medications and illegal drugs have been implicated in reducing counts, motility or morphology or a combination of all three.

To get the best possible semen analysis results:

  • Get the test done at a lab that specializes in semen analysis.
  • Have a second test done three weeks to two months later to confirm the first result. If you lose a portion of the ejaculate, let the lab know so that a second test can be scheduled.
  • Abstain from ejaculation for 2-5 days before the test.
  • Be aware and protect yourself against dangerous environmental exposures at work or home.
  • Improve your overall health by avoiding obesity, smoking, illegal drugs. Ask your pharmacist if your prescribed drugs can affect testicular function and sperm quality.
  • Perform testicular self-exams on a regular basis and see a urologist if you notice something unusual such as a testicular lump, large testicular veins, blood in the urine or semen.

© 2010, Carole. All rights reserved.

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