Semen Analysis

During ejaculation, this fluid moves up through the epididymis and vas. Most of the seminal fluid is produced by glands at the base of the bladder, particularly the seminal vesicles and prostate.

The first part of the ejaculate contains the highest sperm number with the best motility. The proper assessment of semen quality is essential in the diagnosis of several treatable disorders of male fertility. In many male factor patients, however, no specific treatment is available to improve semen quality in which case the semen analysis provides important information about the prospects for natural pregnancy and the use of assisted reproduction.

The semen analysis provides an indication of male fertility but is not an absolute test for fertility because it does not assess important aspects of sperm function, for example the ability of the sperm to locate and penetrate an egg. Furthermore the finding of poor semen quality points to a reduced chance of pregnancy, however natural conception may still occur in some cases. However the more severe the semen defects, the lower the chances.

Routine Semen Analysis
For the semen analysis result to be most valuable, proper collection of the specimen is essential. The semen analysis is performed on a fresh specimen within 1 hour of collection. Before testing, a period of 3 to 5 days of abstinence from ejaculation is recommended. Feelings of anxiety about producing a specimen are common and should be discussed with the doctor or nurse.

Semen Collection Methods
The specimen is best collected by masturbation into a sterile container. This is most conveniently performed in the facility provided at the laboratory however collection at home is acceptable provided the sample is rapidly transported (within 1/2 hour) and kept at body temperature.

Semen collected by interrupted intercourse is not favoured as it risks the loss of sample, particularly the first fraction of the ejaculate. Semen should never be collected into an ordinary condom, which contains substances that kill sperm.

The Analysis
Analysis of the ejaculate includes the characteristics of the seminal fluid (volume, pH) and of the sperm themselves including the number of sperm (called sperm ‘count’ or concentration), their movement (motility) and shape (morphology).

The normal ranges for various parameters of semen quality are shown below: Normal Values Of Semen Variables

• Standard Tests Volume >2.0 ml.
• Sperm Concentration >20 million sperm/ml.
• Sperm Motility >50% with forward movement
• Sperm Morphology >15% normal forms
• White Blood Cells <1 million cells/ml.
• Sperm Antibodies (Immunobead Tests) <50% sperm with adherent particles

The finding of no sperm in the ejaculate (called ‘azoospermia’) suggests either an absence of sperm production or obstruction to sperm outflow. It is most important that an azoospermic semen sample is spun down to carefully examine whether the ejaculate contains even a few sperm. If a few sperm can be found (called “virtual azoospermia) the technique of single sperm microinjection (also called IntraCytoplasmic Sperm Injection, ICSI) may be successful. In these severely infertile men sperm may be appear only intermittently underlining the need for several semen analyses.

Sperm Motility (Movement)
Along with a low sperm count, sperm motility is often impaired in men with ‘idiopathic’ (meaning the cause unknown) poor sperm production. However there are other important conditions which predominantly effect sperm motility, such as sperm autoimmunity, a condition that accounts for about 6% of male infertility. Sperm that show no movement (immotile sperm) may be due to structural problems in the sperm tail or be due to death of sperm (necrospermia). Such couples have an exceedingly low chance of natural fertility but ICSI may provide an alternative.

Assessment for sperm antibodies is an essential initial test in suspected impaired fertility. The immunobead technique is a simple test that can be used to detect antisperm antibodies in blood or semen.

Sperm Morphology (Shape)
Sperm shape is an important predictive indicator of sperm fertilising ability. Compared with other species, the human has a relatively small percentage of sperm showing a “normal morphology (actually defined as being ideally shaped), with as few as 15% normal forms being regarded as the lower limit of normal. Fertility declines as this percentage falls, particularly in men with ejaculates with less than 5% normal-shaped sperm.

This assessment requires great skill and experience. Sperm are specially stained and viewed under a microscope, with assessment of the head, middle and tail regions. Many structurally abnormal sperm have many defects, which may affect all regions of the sperm.

Other Assessments
The percentage of sperm that are alive (sperm vitality) is noted because this declines in association with genital tract infections and disorders of sperm transport through the genital tract.