Semen analysis overview
- A semen analysis is often one of the first tests performed to help establish if a man has infertility issues, which is the inability to produce any sperm or healthy sperm that can fertilize a woman’s eggs.
- A semen analysis measures the number and quality of sperm in the semen sample.
- Approximately 50 percent of infertility in couples is attributed to male factor infertility caused by poor quality sperm.
What is a semen analysis?
A semen analysis can help determine whether a man has the ability to produce sperm and to produce healthy sperm that can fertilize the egg. If any abnormalities are found in the sperm, or if the patient has low sperm production, the analysis can also help determine the appropriate infertility treatments.
Semen samples for testing are collected via masturbation (most common), urological surgical procedures or partner-assisted using a fertility lab-approved non-toxic condom.
To get an accurate determination, a semen analysis should evaluate two samples produced at least seven days apart and not more than three weeks apart. When the analysis indicates abnormal findings a physician will likely request the tests be repeated.
A semen analysis evaluates the quality and quantity of the sperm and the semen (ejaculate material released during male climax) that delivers sperm. The following factors are evaluated in a semen analysis:
Volume of semen
Volume is measured by the amount of semen found in one ejaculate, which ranges from 1.5-5.0 milliliters. A low volume of semen may indicate that the seminal vesicles are not making enough fluid or are blocked.
Liquefaction time measures how long it takes semen, which is a thick gel at the time of ejaculation, to liquefy. Semen should become liquid approximately 20 minutes after ejaculation.
pH refers to the acidity (low pH) or alkalinity (high pH) of the semen.
White blood cell presence
This test determines if excessive white blood cells are present in the semen, which is abnormal.
Fructose presence measures the amount of sugar present in the semen, which provides energy for the sperm. It also gives information about potential blockages in the ducts and tubes.
Sperm count refers to the number of sperm present in a milliliter of semen, commonly over 15 million in a milliliter. Men with a low sperm count — under 15 million sperm in a milliliter of semen (called oligozoospermia) — have a decreased chance of fertilizing their partner’s egg. Complete absence of sperm in the ejaculate is called azoospermia.
Sperm motility measures the percentage of sperm that can move in a forward, normal motion. The highest quality sperm will move in a reasonably straight path and have a high enough velocity to penetrate the firm outer coating of the egg, or the zona pellucida, for fertilization. At least 50 percent of sperm should be mobile an hour after climax.
Sperm morphology is associated with the overall health of the sperm as determined by the sperm’s size, shape and cellular properties. Abnormal shapes, such as a bent tail or a misshapen head, can prevent the sperm from being able to swim and/or fertilize the egg.
Normal morphology also relates to DNA integrity; DNA damage will mean lack of fertilization and the risk for miscarriage will be high. For a normal analysis based on strict criteria, at least 4 percent of sperm should be of normal shape and size.
A postcoital (after sexual intercourse) test is most commonly used when a woman is unable to become pregnant and other tests have not found a cause. The analysis determines whether sperm are present and moving normally in a woman’s cervical mucus after intercourse.
The couple is instructed to have intercourse one to two days before the woman is scheduled to ovulate, when the cervical mucus is thin and flexible. This allows the sperm to move into the uterus through the mucus. Intercourse must occur nine to fourteen hours before the postcoital test is performed.