The Semen Analysis

Most Important Measurements In The Semen Analysis

The semen analysis is considered the “workhorse” test to diagnosing male factor infertility. The test measures a number of parameters but clinicians typically focus on three:

  1. Concentration: The amount of sperm produced within a milliliter of semen
  2. Motility: The percentage of the sperm that can swim forward
  3. Morphology: The percentage of sperm that have the proper shape

If the answer to any one of these criteria is irregularly low, this will likely prompt another semen analysis test and then possibly any number of additional tests or treatments depending on the score and what kind of doctor is treating you.

As we discussed, reproductive endocrinologists and reproductive urologists will likely have differing reactions to the results of a semen analysis. As a result, it’s wise to get the perspective of both if the semen analysis looks abnormal.

Huge Variability

The field of reproductive urology has not agreed upon how to perform the semen analysis, how to interpret it, and how much to rely upon it. This is because the semen analysis suffers from two major weaknesses. First, one man can produce dramatically different samples, even just days apart. Second, the readings require a fair amount of judgement and, as a result, different labs will have different interpretations of the same sample. Below are two studies that nicely characterize how two samples from the same man can produce different readings (Keel) and how various laboratories can dramatically disagree about the same sample (Auger).

Amidst such variability, patients need to carefully select where they have their semen analysis performed and analyzed. The best study we can find, the Augur study referred to above, concluded that laboratories that have less experience and less training see a higher variance in their ability to count sperm (2.9 times more variance than experienced laboratories) and quantify motility (1.4 times more variance than experienced laboratories).

As a result, many reproductive urologists believe that having your semen analysis done at a fertility clinic, rather than at a normal hospital (or regular lab), will drive more accurate results. Because clinics often run 5 – 15 times the number of tests as a hospital and are often much more skilled at discovering if there is any rare sperm available in the sample (minimizing the risk of erroneously diagnosing azoospermia, covered in a future lesson).

The Process

There is sometimes disagreement about how many semen analysis tests are necessary. If the couple is having trouble conceiving, most reproductive urologists will want the man to have at least two tests, regardless of the results on the first. Other doctors will be happy with only one test if the results look normal.

Creating the proper conditions requires a few steps. First, most reproductive urologists insist the man ejaculates within five days of the test, but not within two days of the test. Below is a calendar representation of these windows. Getting this right is especially important to ensure the sample’s sperm concentration reflects what the man is capable of producing under optimized conditions.


Sample Calendar for semen analysis

Around the time of your semen analysis, your doctor will also likely allow you to consume alcohol and caffeine, provided it’s in moderation: as you will see in a few lessons, both can influence sperm quality when consumed above a certain level.

Once you provide a semen sample, it is analyzed within 60 minutes and a report is provided to your doctor. If the doctor requests a second test there is often a two week period between sample collections given the variability discussed above.

Reading The Semen Analysis

What we’re trying to establish with the semen analysis is whether or not the man can produce enough sperm that swim fast enough, and are of the right shape, for some of his sperm to fertilize an egg. As a result, we need to look at the concentration, motility, and morphology in conjunction with one another.

Unless the man is producing no sperm (known as azoospermia), below normal scores in any one category can often be compensated for by normal-ish scores in the other categories. For instance, if the man has a low percentage of motile sperm, but a large concentration of sperm, he may still produce enough motile sperm to fertilize an egg.

While having one below-normal parameter in the semen analysis is almost never a disqualifier for the man to conceive naturally, it certainly doesn’t help. Below you can see how men who have one below normal parameter are 2 - 3 times more likely to have fertility challenges, and when all three parameters are below normal, he is 16 times more likely to be infertile.

Sperm Concentration

Sperm concentration is a function of how many sperm appear in each milliliter of semen the man produces. Sometimes doctors will multiply the man’s concentration by the total volume of semen produced in a sample (again, in milliliters) to calculate a total sperm count.

Oftentimes a doctor will want to see a concentration above 15 million per milliliter. However, and this is important to note, many men achieve pregnancy naturally with concentrations far below the averages.

Below is a histogram of sperm concentrations amongst roughly 700 fertile men and 700 men who cannot conceive naturally. As you can see, at high sperm concentrations, the majority of men are fertile. In the middle-ranges the proportions are more equal, and at low sperm concentrations it’s very possible the man can conceive naturally, but the odds are diminished.

Sperm Motility

Sperm motility measures the percentage of sperm that are able to propel themselves forward. For natural conception to take place, sperm need to travel the relative distance of a human swimming from California to Australia, so motility is crucial. Doctors generally would like to see that at least 40% of a man’s sperm are motile (50 – 60% is average). But, just as with sperm concentration, many men conceive with motility percentages well below average. As you can see below, elevated motility tends to coincide with male fertility, but men are still able to conceive with diminished motility rates (though it appears to be much harder).

Total Motile Count

One number many reproductive urologists like to use is the total motile count (TMC). In effect this translates into the total number of sperm a man produces that able to swim forward. It is often a simple equation:

Totile Motile Count Equation

Many reproductive urologists then consider whether the total motile count is sufficient for any given approach. Most clinicians believe if a man has a TMC of 20 – 40 million, he can conceive naturally. When the TMC is closer to 3 – 5 million, he cannot conceive naturally but possibly through the help of Intrauterine Insemination (IUI), which is a less costly, and less involved process, than IVF (and we’ll cover it more in a future lesson).

Sperm Morphology

Sperm morphology measures the percentage of sperm in a semen analysis that are normally shaped. This parameter causes the most angst amongst patients and so it’s important we make a few points clear about morphology.

First, men generally have a very small percentage of their sperm that are of “normal shape.” A morphology reading in the teens or single digits is not necessarily cause for worry.

Second, grading morphology is an incredibly subjective exercise and it is an unreliable parameter. For that reason it has been hard for the field to correlate morphology levels with any specific outcomes or risks.

Third, there can be worry amongst patients that poor morphology translates into offspring with birth defects. There is little evidence to support that theory.

Fourth, provided there is a sufficient Total Motile Count (TMC), a man with a small percentage of normally-shaped sperm can still conceive naturally. According to the WHO, even men with only 3% of their sperm of normal shape are able to conceive naturally.

If you are in the process of beginning IVF, and the male partner has been diagnosed with male factor infertility, but his only abnormal reading on the semen analysis is a poor morphology, there is good data that shows adding ICSI (a costly fertilization technique, which we cover in the next section) to your treatment is of no help.

The doctors at the University of Utah, after performing a meta-analysis on multiple studies, came to the conclusion that using ICSI to treat poor morphology (in the context of an otherwise normal semen analysis) does not deliver better IVF outcomes. One example of this comes from a single center in New York City, which recorded comparable outcomes in this patient group whether they added ICSI to their IVF or not. You can see their findings below.

Relationship Between Semen Analysis & Other Diseases

There is reason to believe that an abnormal semen analysis correlates with other medical issues, or could be a harbinger of issues to come. A team at Stanford has meticulously reviewed health insurance claims data and started to note a strong correlation between a poor semen analysis and non-ischemic heart disease, peripheral vascular disease, skin disease and metabolic disorders.

Another well-run, retrospective study showed that men with male factor infertility ran a 3x higher likelihood of ultimately developing testicular cancer. That said, the incidence was still incredibly low, at 0.3%.

Pro Tips

  • Have your semen analysis analyzed at a clinic or lab specializing in fertility (as opposed to a regular hospital or lab), as they typically have much more experience.

  • If your sperm count is 0, strongly consider repeating the semen analysis at a fertility clinic’s laboratory. Often these laboratories are better at detecting if there is some sperm in the sample. Also, make sure to consult our lesson on azoospermia.

  • Have a look at the raw data of your semen analysis. If results are rounded off, this may be a sign your results were not read at a reputable and precise laboratory.

  • If the man comes in below average for any semen analysis parameter, consult a reproductive urologist to understand what this implies about your odds of conceiving naturally or through treatment, any inference this might provide about the man’s general health, and any additional evaluation that must be done (often hormonal and sometimes genetic testing).

  • Recognize that unless the man produces no sperm, there’s a chance he may be able to conceive naturally, though it becomes harder with each low parameter.

  • If you are being treated with IVF and a poor morphology is the only concern revealed from the semen analysis, discuss with your clinician whether ICSI is truly necessary.
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