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Sperm 101: How to Interpret the Semen Analysis

Semen analyses can be frightening for couples struggling with infertility. However, it does not have to be. The most important thing to remember when dealing with this test is that, unlike a lot of other blood tests, it has a significant amount of variability. In fact, there is no value (other than azoospermia or having no sperm in the ejaculate) below which a man cannot have children.

The average man produces ~ 1,000 sperm per second. Sperm production is the most rapid process in the human body. Further, unlike women, who have a fixed number of eggs, men regenerate sperm constantly. The sperm production process takes approximately 64 days from the time the sperm is made from the stem cells in the testicles until it is ejaculated. (See Figure 1).

Sperm parameters, while far from perfect, can serve as a guide to what type of treatment a couple may need (see Figure 2). The main issue for couples is we cannot, as of this time, answer the question they are most interested in, which is: If I have sperm parameter X what is my % chance of being pregnant in 3, 6, 12 months? Our lab, along with others, is working daily to try to answer this question. Fortunately the convergence of advanced tests in genetics and bioinformatics analysis may allow us to answer this question in the next 5-10 years.

I see more than a hundred patients with male infertility a month and there are a handful of really good questions that continually seem to pop up, so before we get into the “meat and potatoes” of the semen analysis, I thought I’d address these first.

Does abnormal sperm shape or morphology (teratospermia) increase my chance of having a baby with a birth defect?

The answer to this is a resounding no. Human sperm production is a very inefficient process and a normal man has ~96% of his sperm that look abnormal. Fortunately, the shape of the sperm does not correlate to the genetic material inside.

What is the most important value in a semen analysis that guides treatment decisions?

This would be the total motile count or how many million swimming sperm are present. Total motile count (TMC) is defined as the volume of the ejaculate in ml x concentration of sperm per ml x % motility (percentage of sperm that are moving forward). Thus a man with 5ml of ejaculate, 10 million sperm per milliliter where 50% of the sperm are moving would have TMC calculated as follows:

_TMC (total motile count) = volume (ml) x concentration (M/ml) x % motility _

25 million = 5 ml of ejaculate x 10 million sperm per ml x 50% motility

Multiple studies have determined that TMC, while imperfect, is one of the best predictors of male fertility (see Figure 2).

Can I use my varying total motile count to determine when is the optimal month to try to have a child or whether an intervention, such as hormone therapy for a man, has had an impact on sperm count?

Again, the total motile count (TMC) may change significantly between semen analyses; a lot of this is noise in the system of sperm production. Sperm parameters can vary by up to 400% from test to test, although generally patients stay in roughly the same classification. Much of this variation is due to seasonal variability (sperm counts peak in the early Spring), environmental exposure, exposure to heat, stress and other factors such as hormone levels. TMC is most helpful when used after an intervention to improve male infertility, such as a surgery to ligate a dilated vein in the testicle (varicocele repair). Any intervention will take 3 months to have an impact, due to the time it takes to generate sperm. In other words, the sperm that are ejaculated today were made ~2-3 months ago.

TMC is helpful in that there are certain thresholds that can serve as a guide for what type of therapy a man may benefit from. For example, 5 million swimming sperm give a couple an 8-10% chance of success with intrauterine insemination (where the man’s sperm is placed into his partners uterus when she is ovulating). For men with less than 1 million swimming sperm, it is more likely that they would need in vitro fertilization.

Thus, TMC cannot be used to completely predict pregnancy success, but, when looked at globally, can be an excellent representation of the impact of a treatment (such as hormone therapy or surgery) by a male fertility expert on a man’s reproductive system.

Does it matter which lab I get my semen analysis in?

Yes – big time. This is critical to ensuring a useful test. Not all labs are created equal. Labs that are not based in a fertility clinic do not provide the same quality testing as those done in a high volume fertility center. For example, our lab, at the University of Utah, performs 10-15 semen analyses a day, while a lab in a hospital may perform 1 a week. We always recommend that our patients get a semen analysis from a fertility center, as we often see men who have been told that they have no sperm from an outside center where our analysis finds sperm.

Does abnormal sperm shape or teratospermia mean that I need to do IVF or ICSI?

There is no data to suggest that this is the case. My own published work, which reviewed all the existing literature (Hotaling et al, Fertility & Sterility 2011), demonstrated that men with abnormal sperm shape, compared to those with normal sperm shape, do not have significantly worse outcomes with IVF and do not benefit from ICSI.

Figure 1: A roadmap of sperm production

SA From Hotaling

Figure 2: Using sperm parameters to guide treatment

Seman Analysis 2 From Hotaling

Next, I think it’s important that patients get familiar with the basics of the semen analysis. As I mentioned, if you come in below a “normal value”, most of the time there is no reason for concern. For one, the test is notoriously erratic. For another, many men conceive with a value below what is considered normal, provided other parameters look good.

The reference values for a sperm test are clarified below. Many men (and their partners) find this terrifying. Thus, we will briefly review what each of these values mean. The semen analysis parameters gives a range of these values:

Typically, we need to look at all these values in combination to get the most information from a semen analysis. Briefly, volume is the amount of fluid that comes out when a man ejaculates. Only about 10% of this fluid is actually sperm. If the volume is low, this could indicate a plumbing problem where the sperm simply cannot get out from the testicles or, a problem where some of the sperm goes back into the bladder after a man ejaculates. The count is the total number of sperm and the motility is the number of sperm that move. The progressive motility is the number of sperm that not only move but can progressively move forward. We actually use the number of swimming sperm more than any other parameter.

The morphology is what the sperm look like under the microscope. There are very strict criteria for what a “normal” sperm looks like. Typically, only 4 -10% of a man’s sperm are normal, meaning that the vast majority do not look perfect under the microscope. Many people equate abnormal morphology to children with birth defects. This is completely incorrect. Most male fertility experts would agree that the role of morphology in predicting pregnancy is unclear at best. I would encourage you not to worry about this parameter and simply talk to your doctor about it.

A de Agostini, H Lucas. (2012). Semen analysis. Department of Obstetrics and Gynecology, Geneva University Hospital. Retrieved from

Jones. (2013). Learn to interpret semen analysis. Understand male infertility. Retrieved from

P Stahl, D Stember, P Schlegel. (2011). Interpretation of the semen analysis and initial male factor management. Clinical Obstetrics and Gynecology, 54(4), 656-665.

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