How are the sperm tested?

We examine a number of important sperm factors which all contribute towards a man’s ability to conceive.

Sperm concentration

or ‘sperm count’ in millions per mL of semen. This is done under the microscope using a specialised counting chamber. Normal range 14-16 millions per ml or more.


Sperm motility

Sperm are graded on their ability to swim. The fast-forward swimming sperm being the most fertile. Normal range over 32% progressively motile. Motility measurements are notoriously subjective and inaccurate if performed manually. For this reason NUH uses CASA to assess sperm swimming ability (see below).


Sperm morphology

The shape and size of the sperm are assessed and the number which are ‘normal’ are reported. Normal range >4% normal or more


CASA – Computer Assisted Semen Analysis

CASA is used extensively at NUH as the computer ensures that the result is more or less the same no matter which member of staff performs the test. Not only is this difficult for manual semen analysis to achieve but sperm motility is almost impossible to estimate accurately without the use of a computer. 

CASA provides sperm motility measurements based on individual swimming speed assessed over one second. The system used at NUH was developed and tested here and is used in a number of accredited laboratories.


Other Semen Parameters              

A number of other sperm tests may be offered which reputedly provide additional information to help decide upon which 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.



Results are normally posted back to the referring Doctor within a week, although we generally suggest that patients allow 10-14 days before contacting the GP. Please note results are not given directly to patients over the telephone, if your surgery does not receive the results they will need to contact the laboratory themselves to arrange for a copy result.


Repeat tests

We quite often ask for a repeat of your test. This may be because one or more of the factors listed above may be borderline or below what we call ‘the normal range’. However, abnormalities with the sample can occur for a number of reasons, e.g. previous illness, stress or medication, therefore confirmation of a ‘real’ sperm problem usually requires a second test.

No single semen parameter should ever be considered in isolation. As a rule of thumb, a concentration of more than 5-6 million progressively motile (forward swimming) sperm per ml would be considered as being in the ‘fertile range’ and below this in the ‘subfertile range’.


What if the result is poor?

Although it is still possible to conceive if the sperm are poor, the chances are usually much lower. However, assisted conception treatments such as in vitro fertilisation (IVF) and intra cytoplasmic sperm injection (ICSI) can be very successful even in cases where there are very few apparently functional sperm. T

alking the problem through with someone can often help, especially in the first few days after diagnosis. We therefore have a qualified independent counsellor available, who is experienced in working with men in stressful situations. For an appointment patients must contact the main fertility Unit clinic on Tel: 0115 970 9238 if you wish to make an appointment.


Quality Assurance

Our laboratory staff are highly experienced and well trained in diagnostic semen analysis and have been involved in the training of personnel from all over the world. The laboratory runs a comprehensive quality control program and is enrolled on the UK National External Quality Assurance Scheme (UKNEQAS).


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.


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.