A semen analysis is a lab test that evaluates the health and quantity of sperm in an ejaculate sample. It’s the cornerstone of male fertility testing, typically ordered when a couple has been trying to conceive for at least 12 months without success. The test is also used to confirm that a vasectomy was successful, usually 8 to 16 weeks after the procedure.
What the Test Measures
A semen analysis looks at several characteristics of both the semen itself and the sperm within it. The lab evaluates physical properties of the fluid first: how quickly it liquefies after ejaculation (normally 20 to 25 minutes), its thickness, and its pH level (normally between 7.2 and 8.0). These details matter because overly thick semen can trap sperm and reduce their ability to swim, while an unusually acidic or alkaline pH can signal underlying problems like infection or a blockage in the reproductive tract.
The core of the test focuses on three sperm characteristics:
- Count: How many sperm are present, measured both as concentration per milliliter and total number in the full sample.
- Motility: The percentage of sperm that are moving, and specifically how many are swimming forward in a purposeful direction (progressive motility).
- Morphology: The percentage of sperm with a normal shape, including a properly formed head, midsection, and tail.
Normal Reference Ranges
The World Health Organization published updated reference limits in 2021, based on the 6th edition of its laboratory manual. These numbers represent the 5th percentile of men whose partners became pregnant within 12 months, meaning 95% of those fertile men scored above these thresholds:
- Semen volume: 1.4 mL or more
- Total sperm count: 39 million or more per ejaculate
- Sperm concentration: 16 million or more per mL
- Progressive motility: 30% or more
- Normal morphology: 4% or more
That morphology number surprises most people. Even in fertile men, the vast majority of sperm have some kind of shape abnormality. Only 4% need to look normal under strict grading criteria for the result to fall within the reference range. Falling below any of these thresholds doesn’t mean you can’t conceive, but it does lower the probability and may prompt further evaluation.
How to Prepare for the Test
Preparation is straightforward but important, because even small deviations can skew results. You should avoid any sexual activity that causes ejaculation for 2 to 3 days before the test. Don’t abstain for longer than 5 days, though, as sperm quality starts to decline with extended abstinence.
The sample is collected by masturbation into a sterile container, either at the clinic or at home. If you collect at home, the sample needs to reach the lab within one to two hours. Keep the container upright and at body temperature during transport by tucking it in a pocket or holding it close to your skin. Letting it get too hot or too cold can damage sperm and produce inaccurate results.
What Abnormal Results Mean
When results fall outside reference ranges, the lab report may use specific medical terms. A low sperm concentration (below 16 million per mL) is called oligozoospermia. Complete absence of sperm in the sample is azoospermia. Low motility is referred to as asthenozoospermia, and a high percentage of abnormally shaped sperm is teratozoospermia. You may see these terms on your report, but they’re descriptive labels rather than final diagnoses.
Abnormal results on a single test don’t necessarily reflect your true baseline. Sperm take roughly 72 days to develop, so anything that happened to your body in the previous two to three months can show up in today’s sample. A high fever, a course of medication, heavy alcohol use, regular sauna or hot tub exposure, significant stress, poor sleep, and even seasonal changes can all temporarily drag results down. Being overweight, smoking, and conditions like varicocele (enlarged veins in the scrotum) have more persistent effects.
Because of this natural variability, a single abnormal result is rarely treated as definitive. Most providers will order at least one repeat analysis, spaced a few weeks apart, before drawing conclusions or recommending treatment.
What the Test Doesn’t Tell You
A standard semen analysis provides a useful snapshot, but it has limits. It measures how sperm look and move under a microscope, not whether the DNA inside those sperm is intact. Sperm DNA fragmentation testing, which assesses genetic damage within sperm cells, is not part of a routine analysis. It may be ordered in specific situations, such as recurrent pregnancy losses, but it’s considered a specialized add-on rather than a standard screen.
It’s also worth knowing that normal semen analysis results don’t guarantee fertility. The test can’t evaluate how well sperm interact with cervical mucus, penetrate an egg, or support embryo development. It’s one piece of a larger picture that includes your partner’s fertility health, timing, and other factors. Still, because it’s noninvasive and relatively inexpensive, it’s almost always the first step in a fertility workup for couples who are having difficulty conceiving.