How are the sperm tested?
We examine a number of important sperm factors which all contribute towards a mans ability to conceive. We test:
Sperm concentration or ‘sperm count’. This is done under a microscope, with the normal range of 14-16 millions per ml of seamen or more.
Sperm motility is used to grade sperm on their ability to swim. The fast-forward swimming sperm are the most fertile. NUH uses computer assisted sperm analysis to test sperm mortality. This is the most accurate form of testing.
Sperm morphology is the size and share of the sperm. This is assessed, and the number of which are ‘normal’ are reported. The normal range is >4% normal or more.
At NUH we use Computer Assisted Semen Analysis (CASA) extensively. This ensures that the result is more or less the same, no matter which member of staff performs the test. Not only is manual semen analysis difficult, but sperm motility is almost impossible to estimate accurately without the use of a computer.
The CASA system used at NUH was developed and tested here, and is used in a number of accredited laboratories.
A number of other sperm tests may be offered which provide additional information to help decide what treatment is right for the couple/patient.
At NUH we only provide tests which are associated with considerable ‘validation’ in that the consensus amongst professionals in that the measurements are clearly associated with the ability to conceive. Not only that, but the tests are reliable and reproducible.
If in doubt, patients should query why a certain test is being offered and how its results will alter treatment choices.
Retrograde ejaculation (RE)
When a sperm test shows that hardly any semen is produced we may suspect a rare problem known as Retrograde Ejaculation or RE. This is where, on ejaculation, semen enters the bladder instead of coming out the usual way. This is caused by a weakness of the muscles around the neck of the bladder and is more common in men with spinal injuries, those who have had surgery on the genitourinary (GU) tract or in chronic conditions such as diabetes.
How do we check for RE?
To find out whether sperm have entered the bladder we have to retrieve them from the urine immediately after masturbation.
To achieve this, patients should:
- Empty the bladder
- Masturbate to orgasm and collect any fluid (if present) in the pot provided
- Collect your urine immediately after (when able) in the pot or pots provided
Anecdotal evidence suggests that some men with RE can produce an antegrade (normal) ejaculate if they try to masturbate with a very full bladder, this may prevent the sperm from escaping into the bladder. Men with suspected RE could try this first at home.
Sperm are killed if they spend more than a few minutes in the bladder. Therefore, once RE has been diagnosed, we usually ask for further specimens in order for us to determine whether we are able to retrieve live sperm. To do this, the patient must alter the pH (acidity) and osmolarity (concentration) of their urine and we provide instructions on how to achieve this.
Antisperm antibody (ASA) testing
ASAs are immunoglobulins or proteins which can occur in the seminal fluid, on the surface of spermatozoa and in the blood. Their incidence in men attending infertility clinics is thought to sperm function in the following ways:
- Cause agglutination of the sperm and reduce their motility.
- Impede progression of the sperm through cervical mucus.
- Interfere with the sperm/egg binding process.
The precise effects of ASA on male fertility are controversial because the tests available for their detection are unreliable, and for this reason we no longer perform this test at NUH. Some units may still offer the test but importantly the result rarely has any bearing on deciding upon the treatment required.
What is a test wash?
Test wash is a form of sperm preparation, which is essentially used to harvest as many of the best (functionally normal) sperm from a semen sample as possible and this helps us to determine which particular ART treatment group, a patient is best suited to.
The ‘test wash’ uses a sperm preparation method known as density gradient centrifugation, which separates highly dense, functionally normal sperm from less dense, abnormal sperm. This is also the method used for preparing sperm for assisted conception procedures such as intra-uterine insemination (IUI)
If >5 progressively million motile sperm are harvested in a 0.5ml final sperm suspension, the patient may attempt artificial insemination, however this is meant only as a guide to treatment and other influences such as sperm morphology should also be considered.