In this test, freshly ejaculated semen is examined under the microscope to evaluate the number and quality of sperm and several other characteristics of the semen.
Why the Test is done?
- Infertility: The semen analysis is one of the first tests done to help determine if a man has an infertility problem. About 15% of couples experience problems conceiving, and 35% of the time, the problem can be traced to a male factor.
- After vasectomy (male sterilization): The semen analysis is performed about 6 weeks after surgery to make sure that there is no sperm present in the ejaculate, confirming that the man is sterile.
- After vasectomy reversal: The semen analysis is done to determine if there is sperm present in the ejaculate, indicating that the reversal was successful and fertility has been restored.
- Count: (the number of sperm): sperm concentration is the number of sperm per milliliter. Average concentration is about 60 million per milliliter. A sperm concentration greater than 15 million per milliliter is considered normal.
- Motility: (the percentage of moving sperm). Motility is considered normal when at least 40% of observed sperm, show good forward movement. These are the strongest sperm, swimming fast in a straight line (Grade 4). Some of the sperm may be moving slower in a circle or in crooked lines (Grade 3). Other sperm move their tail but have no forward motion (Grade 2) or fail to move at all (Grade 1).
- Morphology: (the size and shape of the sperm). Morphology is considered normal if 4% or more of the observed sperm have normal shape.
- Volume: greater than 2.0 milliliters is considered normal. A low volume may reflect complete or partial blockage of gland secretions contributing to the seminal fluid. If the volume is less than 1 milliliter, the semen may not be in close enough proximity to the cervix to allow sufficient sperm to swim up to the uterus and fallopian tube.
- White cells: Finding bacteria or white blood cells in the semen indicate that an infection may be present. A semen culture may identify the organism involved and antibiotics can be prescribed to resolve the problem. A repeat semen analysis usually follows.
- PH level: normal pH range is 7.2 – 8.0. Too little or too much acid in the semen is detrimental to the sperm.
- Liquefaction: It normally takes less than 20 minutes for semen to change from a thick gel into a liquid. An unusually long liquefaction time may indicate an infection.
- Fructose level: Semen is analyzed for fructose when there is no sperm in the ejaculate (azoospermia) or if the semen volume is very low (less than 1 ml). Absence of fructose in the semen may indicate blockage of the seminal vesicles which secrete a significant amount of the fluid of the ejaculate.
What Abnormal Results Mean?
- Semen samples may vary from day to day, so if the test is abnormal, you may be asked to repeat it in a month to reevaluate the abnormality. Urological evaluation is necessary to pinpoint the cause for the problem. Sometimes the cause of sperm abnormalities can be traced to genetic defects (cystic fibrosis), hormonal deficiency, environmental factors (such as smoking, hot tubs and marijuana use), or blockage of the ejaculatory ducts.
- Low sperm count can occur in men who are treated with testosterone or anabolic steroids.
- If a varicocele (distended testicular veins) is present, it may disrupt sperm production.
- In some men, low sperm count or complete absence of sperm (azoospermia) may be attributed to deletions of very small regions in their Y chromosome (DAZ).
Absence of sperm in the semen may be caused by:
- Ejaculation of the sperm into the bladder (retrograde ejaculation);
- Congenital absence of the vas deferens (sperm transport ejaculatory duct);
- Scarring of the ejaculatory duct;
- Testicular failure;
- Surgery, chemotherapy or radiation treatment for cancer;
Testicular failure can be distinguished from sperm transport abnormalities by measuring the husband’s hormone levels; these may include Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Testosterone, Prolactin and Thyroid stimulating Hormone (TSH). Testicular biopsy is sometimes recommended to see if the testes are producing sperm. Other tests may include chromosomal analysis and cystic fibrosis screening.