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Semen Analysis

Test Overview

A semen analysis is a test to measure the number and quality of sperm. The lab will also measure the amount of liquid (semen) produced with the sperm.

This test is usually one of the first tests done to help find the cause of sperm-related infertility problems.

Tests that may be done during a semen analysis include:


This is a measure of how much semen is present in one ejaculation.

Liquefaction time.

Semen is a thick gel at the time of ejaculation. It normally becomes liquid within 20 minutes after ejaculation. Liquefaction time is the time it takes for the semen to turn to liquid.

Sperm count.

This counts the number of sperm present per milliliter (mL) of semen in one ejaculation.

Sperm morphology.

This is a measure of the percentage of sperm that have a normal shape.

Sperm motility.

This is a measure of the percentage of sperm that can move forward normally. The number of sperm that show normal forward movement in a certain amount of semen can also be measured. This is called motile density.


This is a measure of the acidity (low pH) or alkalinity (high pH) of the semen.

White blood cell count.

White blood cells are not usually present in semen.

Why It Is Done

A semen analysis is done to find out if:

  • There is a reproductive problem that is causing infertility.
  • A vasectomy has been successful.
  • The reversal of a vasectomy has been successful.

How To Prepare

You may be asked to avoid any sexual activity that results in ejaculation for 2 to 5 days before this test. This helps to make sure that your sperm count will be at its highest. It also makes the test more reliable. If possible, do not avoid sexual activity for more than 1 week before this test. A long time without sexual activity may result in less active sperm.

You may be asked to avoid drinking alcohol for a few days before the test.

Be sure to tell your doctor about any medicines or herbal supplements you take.

How It Is Done

You will need to produce a semen sample. A semen sample is often collected by masturbation. You can do this in a private room or in a bathroom at your doctor's office or clinic. If you live close to your doctor's office or clinic, you may be able to collect the semen sample at home.

  • Collect the semen sample into the container your doctor gives you.
    • Wash and dry your hands and penis.
    • Ejaculate into the container. Do not use any lubricant or saliva. Do not use a regular condom to collect the semen. The powder in a condom can kill sperm. Collect the entire amount of semen you produce.
    • Keep the semen close to body temperature. A good way to do this is by keeping the semen container in an inside pocket. Avoid getting the semen hot or cold.
    • If you'd prefer to collect the sample without masturbating, your doctor may give you a special condom to wear during sex to collect the semen.
  • If you collected the sample at home, take it to the lab or clinic within 1 hour after you collect it.

Since semen samples may vary from day to day, two or three different samples may be checked within a 3-month period. This helps to get accurate testing.

A semen analysis to test how well a vasectomy has worked is usually done 12 weeks after the vasectomy.

How It Feels

Getting a semen sample does not cause any discomfort.


There are no known risks from having this test.


Results of a semen analysis are often ready within a day.

  • Volume. A high or low semen volume may cause fertility problems.
  • Liquefaction time. If semen takes longer than usual to liquefy, this may be a sign of an infection.
  • Sperm count. A low or absent sperm count can cause fertility problems and may be linked to certain conditions. These may include orchitis, varicocele, Klinefelter syndrome, radiation treatment to the testicles, and diseases that can cause shrinking of the testicles.
  • Sperm morphology. The shape of sperm can affect how well they move and penetrate an egg. Sperm that have two heads or two tails, a short tail, a tiny head (pinhead), or a round (rather than oval) head may not function as well. Some of these sperm are usually found in a semen sample. But having a lot of these sperm may make it harder to fertilize an egg.
  • Sperm motility. Sperm must be able to move forward (or "swim") through cervical mucus to reach an egg. A high percentage of sperm that can't swim well may make it harder to fertilize an egg.
  • pH. A high or low semen pH can kill sperm or affect how well they can move or can penetrate an egg.
  • White blood cell count. A high number of white blood cells and bacteria in the semen may be a sign of infection.

If problems are found, more testing may be done. Other tests may include measuring hormones, such as testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), or prolactin. A small sample (biopsy) of the testicles may need to be checked if the sperm count or motility is extremely low.


Current as of: November 27, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

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