Semen analysis has long represented the standard test for evaluating male fertility. Though still useful, the test is not perfect, as it fails to accurately predict fertility status in certain situations. This article will review the interpretation of a semen analysis and briefly present some of the more advanced alternatives that are now available.
It is appropriate to obtain a semen analysis early in working with an infertile couple. It is unacceptable to put a woman through medical procedures and tests without knowing the status of her partner’s semen. Typically, a man is asked to abstain from any ejaculations for two to three days prior to the test. While making specimens at home is preferred, the sample should be brought to the lab within about an hour. It is important to use a cup provided by the lab, as some materials are toxic to sperm.
There a number of parameters reported in the analysis, only a few are really important:
A typical specimen is 1-4cc. While volume does not play an important role in fertility, a low volume suggests an incomplete collection. Conversely, very large volumes may result in dilution of sperm and may cause considerable leakage after intercourse. Some people believe large volumes are associated with infection, but this is not well-established.
A normal specimen should contain 20 million sperm/ml, or more. Most low counts go unexplained, but occasionally this can be hormonally related.
This is expressed as percent of live sperm. Different labs express this differently, but essentially, about 60% of the sperm should be swimming.
This refers to the shapes of the sperm. Over a decade ago, a new “strict” criteria was introduced. The result is that most men have very low numbers. Fourteen percent of “normal formed sperm” is considered normal. In our lab, as with most labs, we almost never see that result. As the number for normal keeps dropping, the usefulness of the test also decreases. The test is widely misunderstood; it is not a test of fertility or a predictor of having a normal baby.
Low morphology has only been associated with low fertilization rates in an IVF lab when natural fertilization is allowed to occur. Many labs also report White Blood Cell numbers (WBC). Elevated levels might be associated with infections like prostatitis. However, WBC’s can look like immature spermatids. Immature spermatids occur more frequently in specimens with low counts, so it is important to make sure the lab has stained the cells specifically for WBC’s.
Semen cultures can also clarify the situation. After decades of experience with semen analysis, it is clear that the WBC test is not a perfect predictor of fertility. For this reason, it is inappropriate to ask a man to undergo the test before he has tried to father a child.
Over the past few years, a number of tests have been developed that more specifically evaluate the DNA content of sperm: Sperm Chromatin Structure Assay (SCSA), DNA Fragmentation Test (Reprosource), Comet Assay, and Tunnel Assay. All the versions attempt to analyze the quality of the DNA in the sperm, which may be more informative than just the semen analysis alone.
If the semen analysis or one of these DNA tests is abnormal, the reproductive endocrinologist, along with a urologist who specializes in male infertility will try to find a cause and possible treatment to improve the sperm quality. Occasionally, no cause or treatment may found, but many of these men can still be helped with IVF and intracytoplasmic sperm injection (ICSI).