What Does a Semen Analysis Really Measure?

A semen analysis measures several separate things: the volume of the sample, how many sperm it contains per milliliter and in total, what proportion are moving and how well, what proportion are normally formed, and how many are alive. Results are compared against reference values in the WHO laboratory manual for the examination and processing of human semen, now in its sixth edition. One point is worth understanding before you read your own results: those reference values come from the fifth percentile of men known to be fertile, and the sixth edition explicitly states they are not sufficient on their own to diagnose infertility. A below-range result is a reason to investigate, not a verdict.

Why is a semen analysis done first?

Male factors are involved in a substantial proportion of infertility cases, either alone or alongside female factors. Men usually have no symptoms, so there is nothing to notice.

It is also the least invasive and least expensive test in the whole workup. Investigating the female partner extensively while leaving the male untested is a common and avoidable mistake.

What does the test involve?

You provide a sample after a specified period of abstinence. The WHO laboratory manual for the examination and processing of human semen specifies 2 to 7 days, and the interval matters because both a shorter and a longer gap change the result. Follow the interval your own clinic gives you.

Producing the sample at the clinic is preferred, since delay and temperature in transit affect the result. Our article on preparing for sperm collection covers the practicalities.

What does each measurement mean?

Volume

How much fluid is produced. Most of it comes from the seminal vesicles and prostate rather than containing sperm itself. A very low volume can suggest a blockage, a problem with those glands, or that part of the sample was lost during collection.

Concentration and total count

Concentration is the number of sperm per milliliter; total count is the number in the whole sample. They can diverge, which is why both are reported: a normal concentration in a very small volume still means a low total number.

Motility

The proportion of sperm that are moving, and how well. Laboratories report total motility and progressive motility separately, the latter meaning sperm moving purposefully forward rather than in place. Progressive motility is the more meaningful figure for natural conception and for IUI, both of which require sperm to travel.

Morphology

The proportion of sperm with a normal shape, assessed against strict criteria. The percentage considered normal is much lower than people expect, so a figure that sounds alarmingly low may be entirely within range. This is the parameter most often misread by patients.

Vitality

The proportion of sperm that are alive. This is particularly useful where motility is very low, because it distinguishes sperm that are alive but not moving from sperm that are dead, and those point to different causes.

How should you read your results?

Measurement	WHO sixth edition lower reference limit
Semen volume	1.4 mL
Sperm concentration	16 million per mL
Total sperm number	39 million per ejaculate
Total motility	42 percent
Progressive motility	30 percent
Normal morphology	4 percent

Two things about these figures are commonly misunderstood. They are the fifth percentile of men known to be fertile, so a result below one of them places you in the lowest 5 percent of that group rather than outside the range of men who conceive. And the sixth edition states explicitly that this lower limit does not distinguish fertile from subfertile men, and that clinical information must be used alongside the semen analysis. Note also that the normal morphology figure of 4 percent is far lower than most people expect, which is why that result in particular is so often misread as alarming.

Laboratories do not all report against the same edition, and the previous fifth edition used different figures, including 15 million per mL for concentration. Ask us which edition our laboratory reports against so you are reading your own result against the right scale.

Semen results also vary considerably between samples from the same man, so a single below-range result is usually repeated before conclusions are drawn. A poor result during or after an illness, particularly with a fever, may not reflect your baseline.

What happens if the result is abnormal?

• Repeat the test, usually after an interval, to confirm the finding.
• Investigate the cause, which may involve hormone tests, examination, or genetic testing where no sperm is found.
• Address modifiable factors. Sperm production takes roughly two to three months, so changes need that long to show. See our articles on smoking and fertility and foods that nourish sperm.
• Treatment. Where the count or motility is low, ICSI can be used. Where there is no sperm in the ejaculate, it can often be retrieved surgically through TESA, PESA or TESE.

We at Millennium IVF Clinic carry out semen analysis and will go through your results with you. You can arrange a consultation with our team.

Frequently asked questions

Does a below-range result mean I am infertile?

No. The WHO reference values are drawn from the fifth percentile of fertile men, and the sixth edition states they are not sufficient alone to diagnose infertility. It means further investigation, not a conclusion.

How long should I abstain before the test?

The WHO manual specifies 2 to 7 days. Follow the interval your clinic gives you, and tell them if you were outside it, since it affects interpretation.

Should the test be repeated?

Usually yes, if the first result is abnormal. Results vary considerably between samples from the same man.

Can a semen analysis show why the result is abnormal?

No. It describes what the sample looks like, not why. Establishing the cause needs further investigation.