Assisted Reproduction TechniquesDiagnostic tests

The FISH test on Spermatozoa

What is the FISH test on spermatozoa?

The fluorescence in situ hybridisation (FISH) is a technique that has revolutionized classic cytogenetics by applying knowledge on molecular biology. Thanks to this technique, we can examine the genetic material of male gametes by using fluorescent probes that are specifically attached to a certain chromosome and through which we can display the number of these on each of the ejaculated spermatozoa.

The analysis through FISH on the ejaculated sperm will allow us to determine the levels of spermatozoa with abnormal chromosome count and to evaluate whether they exceed the limits of normality or not.

the fish test

Why is this technique important?

Any somatic cell in the human body has 23 pairs of chromosomes, in other words, 2 copies of each chromosome. On the other hand, in order for human gametes (spermatozoa and ova) to be normal in terms of their chromosome content they must have 23 chromosomes, that is to say a single copy of each chromosome. In order to be able to reduce their chromosome count by half, a complex process of cell division, which is called meiosis, is required. If this process is not carried out correctly, chromosomes won’t be distributed equally and gametes with chromosomal abnormalities will be formed.

How many chromosomes are studied?

The FISH test on spermatozoa usually analyses 5 chromosomes, the sexual chromosomes (X and Y) and the chromosomes 13, 18 and 21. This analysis can be extended to other chromosomes upon recommendation of the clinical history. The number of spermatozoa analysed is usually 1.000.

When is this technique indicated?

This test would be recommended in the following cases:

  • Failure of implantation
  • Repeated miscarriages
  • Previous pregnancy with a chromosomal disorder
  • Patients who have undergone chemotherapy or radiotherapy
  • Patients suffering from severe Oligozoospermia or Teratozoospermia

Do you wish to fix an appointment?

You can fix an appointment to do the FISH test on spermatozoa:

  • Calling +34 91 788 80 70
  • Or filling in the form you can find in this page

How is the sample sperm obtained for its analysis?

In order to guarantee the maximum reliability of the spermogram diagnosis, the sperm sample shall be obtained following these indications:

  • The sample should be collected after 2-4 days of sexual abstinence. A much longer abstinence is not recommended. (The abstinence period must be neither shorter than 2 days, nor longer than 4 days).
  • Collect the sperm sample in a sterile container, we will give you one at Ginefiv, nevertheless you can buy these containers in a pharmacy.
  • Masturbation is the standard method for the sperm sample collection,  as neither the interruptus coitus, nor the use of commercial condoms is accepted.
  • The collection of the sperm sample must be performed under hygienic conditions (you will need to wash your hands previously).
  • Be sure that the whole sample is inside the sterile container, because in case most of it falls out of the container, the sample will not be valid. Don’t worry if just a little part of the sample falls out.
  • In the event, you obtain the sample at home:
    • Once you have obtained the sample, make sure you have closed the container properly and that the sample doesn’t get too cold (the sample has to be kept at a temperature between 20ºC and 30ºC, avoiding abrupt temperature changes. That’s why we recommend carrying the sample in an interior pocket).
    • The maximum period of time between the sperm sample collection and its delivery at the laboratory should be of one hour.
  • If you have a temperature (fever) between 7 to 10 days before the sperm sample collection or if you are taking antibiotics, you should contact the laboratory to postpone your appointment.
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