FISH - diagnostics of spermatozoa

Problems with conception are not always related to sperm count or motility; sometimes the cause lies in their genetic quality. Even with normal semen analysis results, chromosomal abnormalities may be present that affect fertilization or embryonic development. In such cases, more in-depth diagnostics are required, specifically the FISH method, which allows for the assessment of the chromosomal makeup of sperm and the identification of underlying causes of male infertility.

What is the FISH method?

FISH analysis (fluorescence in situ hybridization) is a modern genetic test used to detect chromosomal abnormalities in spermatozoa. It is a method of molecular cytogenetics that allows for the assessment of the number of chromosomes in sperm cells using fluorescently labeled DNA probes specific to certain chromosomes (specifically X and Y, as well as 13, 18, and 21).

Principles and Methods of FISH Analysis of Semen

FISH detects aneuploidies—abnormalities in chromosome number—that can cause male infertility, failed attempts at conception, recurrent miscarriages, or the development of embryos with genetic abnormalities (such as Down syndrome or Klinefelter syndrome).

In clinical practice, this test is used as part of a comprehensive diagnosis of male infertility, especially before undergoing assisted reproductive technologies. It helps assess genetic risks, influences the choice of infertility treatment methods, and reduces the likelihood of embryonic developmental abnormalities.

Important! The FISH method counts only a certain number of sperm in the sample, but even that is enough to identify a high risk of genetic abnormalities.

Sperm Analysis Using the FISH Method: Main Indications for the Procedure

The FISH method is used in genetics when there is a suspicion of chromosomal abnormalities that may affect male fertility, the fertilization process, and subsequent embryo implantation in the uterus. This is an in-depth diagnostic test that helps identify causes not detectable by standard semen analysis.

Main indications for in-depth sperm analysis:

infertility of unknown cause;
the man's age is over 45;
normal semen analysis results in the absence of pregnancy;
repeated unsuccessful attempts IVF or other assisted reproductive technologies;
recurrent miscarriages in the partner;
suspected high levels of aneuploidy in sperm;
cases of pregnancy in couples with fetal chromosomal abnormalities;
preparation for assisted reproductive technology programs;
risk factors that may affect genetic material (age, unhealthy habits, radiation or chemotherapy for cancer, etc.).

The FISH method allows for the analysis of sperm DNA and helps the doctor determine the most effective infertility treatment strategy for the couple

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The FISH Method: Stages of Diagnosis

FISH analysis of semen requires a high degree of accuracy at every stage, since it involves the evaluation of the cells’ genetic material. The sequence of the examination is as follows:

Sample Collection. The patient provides a semen sample at the laboratory in accordance with the preparation guidelines.
Cell preparation. Sperm cells are processed, fixed, and mounted on a microscope slide.
DNA denaturation. Conditions are created to uncoil the DNA so that the probes can bind to the desired regions.
Application of fluorescent probes. Special DNA probes specific to certain chromosomes are added.
Hybridization. The probes bind to the corresponding regions of the chromosomes.
Microscopic analysis. Under a fluorescence microscope, the signals are evaluated and the number of chromosomes in the sperm is counted.
Interpretation of results. The level of aneuploidy is determined, and genetic risks are assessed.

The FISH method allows for the most accurate detection of chromosomal abnormalities in sperm and is used in the modern diagnosis of male infertility. In the comprehensive diagnosis of male infertility, the following may also be used: sperm viability test, which helps determine what percentage of the cells are capable of active function.

How should you prepare for a semen analysis?

Proper preparation for a semen sample for FISH analysis affects the accuracy of the results. Key recommendations:

abstaining from sexual intercourse for 2–5 days before the test;
Avoid alcohol and overheating (saunas, hot baths) for 2–3 days;
limit strenuous physical activity and stress as much as possible;
Do not take antibiotics or other medications without consulting a doctor;
Have the sample tested at a specialized laboratory to ensure that the conditions for collecting the biological material are met.

Please note! It is recommended to collect the biological sample for FISH analysis through masturbation. Semen collected from a condom is not suitable, as it may alter its properties due to contact with latex and lubricant, which could lead to false results.

Advantages and Disadvantages of the FISH Method

The FISH method is considered one of the most informative tools for diagnosing male infertility, as it allows for the accurate determination of the genetic status of sperm. It is also worth noting other advantages of this test:

allows for the detection of chromosomal abnormalities that are not visible in a standard semen analysis;
helps assess the level of aneuploidy in sperm;
improves the accuracy of diagnosing the causes of male infertility;
helps reduce the risk of genetic birth defects in the fetus.

It's interesting to know! The FISH method is widely used not only in reproductive medicine, but also in genetics and oncology to detect chromosomal abnormalities in cells.

For the sake of an objective assessment, it is worth noting certain shortcomings of the analysis:

assesses only a certain number of sperm cells, rather than the entire sample;
examines a limited number of chromosomes (most commonly chromosomes 13, 18, 21, X, and Y);
does not provide a complete picture of all possible genetic disorders;
requires specialized equipment and laboratory expertise;
is more complex and expensive than a standard semen analysis.

Sperm analysis using the FISH method should be used when indicated, particularly when a more in-depth assessment of genetic factors is needed and appropriate infertility treatment options must be selected.

FISH Sperm Analysis at the IVMED Clinic

IVMED offers FISH testing of sperm as part of a comprehensive approach to identifying the genetic causes of male infertility. The testing is conducted in our in-house laboratory using molecular cytogenetic technologies, which allow us to accurately assess the chromosomal makeup of sperm and identify risks to reproductive function.

Benefits of undergoing FISH testing at the IVMED Reproductive Medicine Clinic:

Expert Genetic Diagnostics. State-of-the-art equipment, combined with the expertise of our specialists, ensures high accuracy in prenatal diagnosis.
State-of-the-art laboratory facilities. The Use of Fluorescent Probes for Accurate Chromosome Analysis.
Experience treating complex cases of infertility. The clinic has many years of experience and has helped thousands of couples become parents.
Individual tactics. The subsequent strategy is selected based on the level of aneuploidy (ranging from correction to ART programs).
A comprehensive approach. The ability to combine FISH analysis with other diagnostic and treatment methods within a single clinic.
Confidentiality and Support. The patient receives not only the results, but also an explanation and recommendations on next steps.

The FISH method is a valuable tool in modern reproductive medicine that allows for a more in-depth assessment of sperm genetic quality and the detection of hidden chromosomal abnormalities. It helps pinpoint the cause of fertility issues more accurately and select an effective treatment strategy, reducing risks to the future fetus and increasing the chances of having a healthy child.

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