A semen analysis is used to evaluate male fertility — a man's ability to reproduce. This test, also is called a sperm count, is used to measure the amount and quality of seminal fluid or ejaculate. Seminal fluid contains male reproductive cells (semen or sperm) and is usually expelled through the penis during ejaculation (sexual climax; orgasm).
A semen analysis can also be used to help diagnose Klinefelter's syndrome, which is the most common congenital (inherited) cause for testosterone deficiency. This condition, which is caused by an extra X chromosome, results in male infertility (inability to conceive after one year of unprotected intercourse), sparse facial and body hair, abnormal breast enlargement (gynecomastia), and small testes. In most cases, at least two sperm counts are performed following vasectomy to look for sperm in the semen.
The semen analysis is usually performed by a urologist or a male fertility specialist or in a specialized laboratory. Seminal fluid can affect factors such as sperm shape, function, and movement, so the entire ejaculate is examined.
Prior to a semen analysis, ejaculation should be avoided for 2-3 days. The semen sample can be collected in a sterile glass container through masturbation (i.e. sexual stimulation) or through sexual intercourse using a special type of condom provided by the physician.
The sample must be analyzed within 1-2 hours to provide accurate results. Many specialists require three different semen samples to account for factors that can affect results, such as variations in temperature and laboratory errors. It often is recommended that the results of the tests do not vary by more than 20%.
Semen analysis includes the following factors:
- Volume (total volume of ejaculate)
- Standard semen fluid test (e.g., thickness, color, acidity)
- Concentration (sperm count; sperm/mL)
- Morphology (sperm shape and structure; associated with sperm health)
- Motility (% of sperm that show forward movement; mobility)
- Total motile count (total number of moving sperm)
Normally, seminal fluid is clear to milky white in color, thick and sticky (viscous) in consistency, has a pH (acidity) level between 7.8 and 8.0, and contains few or no white blood cells (leukocytes).
World Health Organization (WHO) Reference Values (2009) for Fertile Men
|Semen Volume (ml)||1.5 ml||2 ml|
|Concentration (Mill/cc)||15 Mill/cc||22 Mill/cc|
|Total Number (Mill/Ejac)||39 Mill/Ejac||69 Mill/Ejac|
|Motility (%)||40 %||45 %|
|Progressive Motility (%)||32 %||39 %|
|Normal Forms (%)||4 %||5.5 %|
|Vitality (%)||58 %||64|