A semen analysis (sperm test) is a test that checks to see if the semen and sperm made by the male partner meets clinically relevant criteria. The sample is usually produced by masturbation and collected into a pot provided by the clinic. The sample is then specially prepared and looked at under the microscope in the laboratory.
A number of different things are looked at and recorded:
- The volume of the sample is measured.
- The number of sperm is counted.
- The movement of the sperm is observed and described.
- The percentage of sperm with normal shape and size is reported.
These results are then be reviewed by your doctor and discussed with you.
It is very important that the instructions given to you by the clinic for producing the sample are carefully followed, otherwise the result of the test may be inaccurate.
A semen analysis evaluates certain characteristics of a male’s semen and the sperm contained in the semen. An analysis is performed when investigating a couple’s subfertility or after vasectomy to verify that the procedure was successful.
The characteristics measured by semen analysis are only some of the factors determining semen quality. It is important to understand that it is the function of the sperm that is important rather than the actual numbers in a report and that the interpretation of the result must take into account the entire assessment of a couple and their wishes and expectations. It is known that 30% of men with a “normal” semen analysis actually have abnormal sperm function. Conversely, men with poor semen analysis results may go on to father children.
Examples of parameters measured in a semen analysis are: sperm count, motility and morphology.
Sperm density or sperm concentration measures the concentration of sperm in a man’s ejaculate. Over 15 million sperm per millilitre is considered normal, according to the World Health Organisation (WHO) in 2010. Older definitions state 20 million per ml. A lower sperm count is considered oligozoospermia. A vasectomy is considered successful if the sample is azoospermic. The average sperm count today is around 60 million per millilitre in the Western world, having decreased by 1-2% per year from a substantially higher number decades ago.
Total sperm count
Total sperm count, or total sperm number, is the total number of spermatozoa in the entire ejaculate. By WHO, the lower reference limit (5th percentile) is 39 million per ejaculate.
Sperm motility describes the movement of the sperm. Motility is divided into four different grades:
- Grade a: Sperm with progressive motility. These are the strongest and swim fast in a straight line. Sometimes it is also denoted motility I.
- Grade b: (non-linear motility): These also move forward but tend to travel in a curved or crooked motion.
- Grade c: These have non-progressive motility because they do not move forward despite the fact that they move their tails. Grade d: These are immotile and fail to move at all. Some authorities define normal motility as 60% of observed sperm, or at least 8 million per ml, showing good forward movement. The WHO has a value of 40% for grades a+b+c or 32% a+b and this must be measured within 60 minutes of collection. WHO also has a parameter of vitality, with a lower reference limit of 58% live spermatozoa. A man can have a total number of sperm far over the limit of 15 million sperm cells per millilitere, but still have bad quality because too few of them are motile. However, if the sperm count is very high, then a low motility (for example, less than 40%) might not matter, because the actual number of motile sperm is still sufficient. The other way around, a man can have a sperm count far less than 15 million sperm cells per ml and still have good motility, if more than 40% of those observed sperm cells show good forward movement.
The morphology of the sperm is also evaluated. With WHO criteria as described in 2010, a sample is normal (samples from men whose partners had a pregnancy in the last 12 months) if 4% or more of the observed sperm have normal morphology.
Morphology is a predictor of success in fertilizing oocytes during in vitro fertilisation. In any one sample, up to 100% of the spermatozoa have observable defects and as such are disadvantaged in terms of fertilising an oocyte.
Also, sperm cells with tail-tip swelling patterns generally have a lower frequency of aneuploidy.
WHO regards 1.5 ml as the lower reference limit. Low volume may indicate partial or complete blockage of the seminal vesicles or that the man was born without seminal vesicles. In clinical practice, a volume of less than 1.5? ml and an absence of sperm should prompt an evaluation for obstructive azoospermia, provided it has been at least 48 hours since the last ejaculation to time of sample collection.
WHO criteria specify normal as 7.2-7.8. Acidic ejaculate (lower pH value) may indicate one or both of the seminal vesicles are blocked. A basic ejaculate (higher pH value) may indicate an infection. A pH value outside of the normal range is harmful to sperm.
The liquefaction is the process when the gel formed by proteins from the seminal vesicles is broken up and the semen becomes more liquid. It normally takes less than 20 minutes for the sample to change from a thick gel into a liquid.. In the WHO guidelines, a liquefaction time within 60 minutes is regarded as within normal ranges.
- Aspermia: absence of semen
- Azoospermia: absence of sperm
- Hypospermia: low semen volume
- Oligozoospermia: low sperm count
- Asthenozoospermia: Poor sperm motility
- Teratozoospermia: sperm exhibit more morphological defects than usual
Booking a Test
Reproductive Health Group offers a semen analysis service for both fertility assessment and after vasectomy for confirmation of success. Samples can be produced at home and delivered to the clinic within one hour. Alternatively they may be produced onsite in comfortable and discrete surroundings. Results will be available within one working day.
Tests can be booked in advance by calling 01925 202180 or book an appointment here.