Interpretation of Semen Analysis Testing
There exists quite a bit of controversy about what are considered “normal” semen parameters, as well as what “normal” means when it comes to male fertility. So let’s make a few general statements about semen analysis testing before we dive into the details.
1. Semen analysis testing is not a perfect predictor of male fertility potential, but it is the best overall general test that we have available at this point in time.
2. The best general predictor of overall sperm quality is the total motile count (TMC).
3. In general, the higher the numbers and the better the quality of sperm present, the greater the fertility potential of that man, so it makes sense to try to optimize semen parameters in all couples who are trying to conceive. There is evidence that this is even the case in couples who are undergoing treatments such as in vitro fertilization. When IVF/ICSI was first being developed, some researchers thought that this technology would compensate for any deficiencies in sperm quality. However, there is now mounting evidence that better-quality sperm have the potential to provide higher success rates when used with these types of female fertility treatments. Therefore we feel that all couples can potentially benefit from optimizing the man’s sperm quality.
Defining “Normal” Semen Parameters
You might think that three and a half decades of research on typical semen parameters would have resolved most of the questions and controversies about what “normal” semen parameters should be. Unfortunately, both patients and physicians are still routinely confused about what “normal” means when it comes to interpreting semen analysis results. I regularly see men in my office who have good semen parameters but were told that they have significant abnormalities. On the other hand, every year large numbers of men are told that their semen parameters are normal when in fact they have significantly decreased fertility potential. Why all the confusion?
Part of the problem lies in the fact that specific sperm counts and quality do not always match up nicely with fertility outcomes. Some couples with really low sperm counts are successful at establishing a pregnancy naturally, while others with completely normal semen parameters (and no problems found on female fertility testing) end up needing to utilize advanced treatments such as IVF/ICSI, and sometimes these are not even successful. Elements of chance as well as other, yet-to-be-identified fertility problems that do not show up on currently available fertility testing certainly play a role. But in general, the numbers and quality of sperm are the strongest predictor of a man’s overall fertility potential that we have at this time.
"Normal" Semen Parameters
The semen analysis test evaluates multiple characteristics, but the four that are generally considered to be the most important are:
1) Ejaculate volume (the amount of fluid that comes out with ejaculation)
2) Density (the number of sperm present)
3) Motility (the percentage of those sperm that are swimming)
4) Morphology (the percentage of sperm that have normal shapes)
The following table shows the most recent (2010) World Health Organization criteria for “normal” semen analysis values, as well as the 1999 WHO criteria for comparison:
At first glance this seems pretty clear-cut. If a man has a sperm count of at least 15 million sperm/cc, at least 40 percent of the sperm are swimming, and at least 4 percent of them have normal shapes, then his fertility potential is just fine and any fertility problems must be either just bad luck so far or problems from the female side, right? Not necessarily.
Let’s look at how the WHO came up with these criteria. The WHO evaluated 4,500 men from fourteen countries and based the “normal” values on a subset of 1,800 men who were able to conceive naturally within twelve months. Of these 1,800 men, the bottom 5 percent of semen parameter values were labeled “abnormal,” with the remaining 95 percent of values being labeled “normal.”
Consider a man with a sperm count of 15 million who was told that his sperm count was “normal.” How comfortable should that man feel about his fertility potential knowing that according to the WHO data, of the men who were able to successfully conceive within a year’s time, 95 percent had a higher sperm count than he has? In addition, of the men in the study who were not able to conceive naturally within a year, 85 percent had a sperm count higher than 15 million. Similar comparisons can be made for motility and morphology results as well.
Overall, an estimated 50 percent of infertile men (defined as unable to conceive naturally within a year) have semen parameters that fall within the “normal” range as defined by the WHO criteria. Obviously, the WHO’s “normal” ranges should undergo further scrutiny.
A Potentially Better Definition of "Normal" Male Fertility Potential
I would argue that a better definition of male fertility potential would be to use the following parameters as “normal”:
Later sections in this website will explore in more detail each of the individual parameters of the semen analysis test, as well as explain why I consider the above criteria to be the best estimate of "normal" fertility at this point in time.
Variation: When Not to Worry
Many patients are confused and frustrated when they see unexpected differences in their numbers between one semen analysis and another—especially when parameters that seemed normal on an earlier test appear to be going in the wrong direction on a later test. But such differences aren’t always something to worry about.
Scientific studies that examined ejaculations by the same man over a period of time show significant week-to-week variation among samples. This natural variability can make accurate determinations of relative fertility or responses to male fertility treatments challenging. In general, I consider about a 20 percent swing in semen parameters to be within the normal expected range of natural variation due to the body’s normal mildly fluctuating sperm production process. Larger swings are more likely to represent a real change in sperm quality for some reason.
When questions arise as to whether an observed change is due to natural variation, a real physiologic change, or lab error, additional semen analyses can be helpful in observing general trends over time. For example, if I have a patient who has two semen analyses with markedly different results, I will typically order a third “tie-breaker” analysis at least ten weeks after the second test to get a more accurate picture.