Sperm Chromatin Integrity Tests (TUNEL and SCSA)

Pooyesh Fertility Clinic

Why Test Sperm Chromatin Integrity?

In advanced evaluations of male infertility, routine semen analysis (count, motility, and morphology) is often not enough. In some cases, semen parameters appear normal, yet couples still experience infertility, repeated IVF failure, or recurrent miscarriage. In such situations, it becomes essential to assess the health of sperm chromatin (the DNA inside the sperm).

Studies have shown that the poorer the sperm quality, the greater the likelihood of DNA damage. In men with defective sperm or unexplained infertility, sperm DNA fragmentation can reduce the success of assisted reproductive techniques (ART). Therefore, evaluating DNA integrity before choosing the appropriate treatment method is highly recommended.

With proper treatment, sperm quality can often be improved when DNA damage is detected. Among the available laboratory methods, the TUNEL test and SCSA are widely used to assess sperm DNA fragmentation and identify men at risk of contributing to unhealthy pregnancies. These tests can be performed on both fresh and frozen sperm samples.

 

Why is Sperm DNA Integrity Important?

Healthy sperm DNA is critical to ensure that intact genetic information is passed on to the embryo. DNA damage in sperm can lead to:

  • Reduced fertilization potential
  • Implantation failure
  • Higher risk of recurrent miscarriage
  • Lower success rates in assisted reproductive treatments

Sperm DNA Integrity and Pregnancy

  • While natural and healthy pregnancies can still occur with sperm showing DNA fragmentation, the likelihood is significantly reduced.
  • The higher the proportion of sperm with fragmented DNA, the lower the chance of a successful pregnancy.
  • Embryos formed from sperm with DNA damage generally have poor prognosis, reduced implantation rates, and lower developmental potential.
  • Research indicates that fertilization with damaged sperm DNA may trigger apoptosis (cell death), genetic mutations, early embryo arrest before the blastocyst stage, miscarriage, or congenital abnormalities.

Causes of Sperm DNA Fragmentation

  • Factors that can damage sperm DNA include:
  • Oxidative stress
  • Genital or systemic infections
  • Presence of white blood cells in semen
  • Febrile illnesses
  • Testicular overheating
  • Poor diet and lifestyle
  • Certain medications, especially antibiotics
  • Advanced paternal age
  • Varicocele
  • Smoking and tobacco use
  • Exposure to ionizing radiation (X-rays, gamma rays)
  • Environmental and occupational toxins

Preparation Before TUNEL or SCSA

Preparation is similar to that for a standard semen analysis, with one difference: the time from the last ejaculation should not exceed 72 hours (3 days).

Test Hours

  • Saturday to Wednesday: 7:00 AM – 3:00 PM
  • Thursday: 7:00 AM – 11:00 AM
  • Friday & Holidays: No semen analysis is performed
  • No prior appointment is required for this test