Sperm Aneuploidy Test
Around 60% of pregnancies result in miscarriage in couples with an increased incidence of chromosomal abnormalities of the sperm.
Sperm Aneuploidy Test is a diagnostic tool used to detect the genetic cause of male infertility. This test examines the sperm chromosomes for any abnormalities. It involves examining the sperm sample and evaluating the percentage of spermatozoa with chromosomal abnormalities. Any presence of abnormal number of chromosomes in the sperm is detected and reported using this test. It also gives a detailed evaluation of the chromosomal involvement in spontaneous miscarriages and in children with chromosomal abnormalities. The SAT should be performed specially in cases where male infertility is the main cause of failure to conceive, since there is a higher risk of transmitting the sperm chromosomal abnormality to their offspring’s.
The chromosomes mostly involved in spontaneous miscarriages and affected children with chromosomal abnormalities are chromosomes 13, 18, 21, X and Y.
What is Aneuploidy?
To understand this test further one must know the principle on which it is based, the test is used to detect Aneuploidies in the sperm chromosome. Aneuploidy is defined as an abnormality in the number of chromosomes either by duplication or by loss of the chromosome(s). In simple words; there are 46 chromosomes in the human body paired into 23 sets. Any addition or loss to this number of chromosomes is called Aneuploidy. Out of the 23 pairs of chromosomes, 22 are autosomes and one pair is of the sex chromosomes (X and Y).
When should one get the SAT?
Sperm Aneuploidy test is recommended in the following case:
- Couples who have had recurrent miscarriages of unknown cause in the past
- Those who have experienced failed IVF treatments multiple times
- Couples in which male infertility is involved majorly a low sperm concentration is associated with increased chances of sperm chromosomal abnormality
- Couples who had a previous pregnancy with chromosomal abnormality
- Males with a raised FSH (Follicle Stimulating Hormone) level
- Oligoasthenoteratozoospermia – this condition includes three spermatic abnormalities low number of sperm, poor sperm movement and abnormal sperm shape.
- Exposure to harmful substances
- And quite rarely those who have had chemotherapy or a radiotherapy in the past.
Exogenous factors causing Sperm Aneuploidy:
- Cigarette smoking
- Chemo or radiotherapy within the last two years
- Exposure to ionizing radiation
- Exposure to environmental pollutants
- Occupational pollutants exposure
- Advanced age.
What to do if the SAT result comes abnormal?
If a couple undergoes a SAT and the results are abnormal then they would require a genetic counselling, which is available at the infertility clinics. The couple would be given options according to their case, and would be advised to go under the process of PGS (Pre implantation Genetic Screening), this process detects chromosomal abnormalities in the embryos once they are formed and helps the couple to choose a normal embryo for transfer into the uterus, hence decreasing the miscarriage risk and increasing pregnancy rate.
BENEFITS OF SAT:
1. SAT increases the rate of pregnancy
2. Decreases the risk of miscarriage
3. It is a useful test to provide genetic counselling to infertile couples previous to an IVF treatment
4. Helps identify males who have a low chance of reproductive success.
PROCEDURE OF SAT:
After, preferably three days of abstinence, an ejaculate is collected under clean conditions in a sterile container and transported to the lab at room temperature. In the lab the sample is washed with a buffer medium and can be stored in the fridge at 4 degrees Celsius for up to 3 days.
Around 1000-2000 sperms per sample are analyzed using the Fluorescence in Situ Hybridization method, commonly called as FISH method. The triple FISH method is used to detect abnormalities of chromosome 18, X chromosome and Y chromosome, whereas the dual FISH method is used for chromosome 13 and chromosome 21 (Down syndrome).
The sample is diagnosed as abnormal when there is an increased number of chromosomal abnormality in the sperm as compared to the normal sperm used as fertile controls.
The results are received within 2 weeks’ time, and it is advisable to see your infertility specialist irrespective of the test being normal or abnormal, in order to discuss your options further, or the next step in the process of your infertility treatment.