Sperm DNA fragmentation

High sperm DNA fragmentation is associated with reduced natural pregnancy rates and assisted conception pregnancy rates as well as live birth rates. Sperm DNA fragmentation also leads to higher miscarriage rates, as published in the ESHRE Recurrent Pregnancy Loss 2017 Guideline. High levels of DNA fragmentation may be reduced by considering varicocele repair, treatment of underlying infections or inflammation, changes in lifestyle, or with antioxidant supplements.

When requesting Sperm DNA Fragmentation there are two options. Please specify whether the request is for sperm DNA fragmentation by SCSA or COMET.


Sperm Chromatin Structure Assay (SCSA®) [SEXT]

This test has the ability to measure large numbers of cells (between 5,000 and 10,000 sperm), rapidly in an ejaculate. The SCSA® test monitors the changes in fluorescence of a probe, acridine orange, to detect both single and double DNA strand breaks using flow cytometry.

It has been developed using human and animal models over the last 35 years, and is one of the most statistically robust tests available for sperm DNA fragmentation. It is a standardised, validated CLIA-approved test with high reproducibility and low variability. The test requires a minimum sperm count of approximately 1 million/ml.


Sperm COMET® Assay [CMET]

When sperm counts are limited, DNA fragmentation can be effectively assessed using the Comet® assay as only ~5,000 sperm are required. The Comet® assay uses electrophoresis to determine abnormal sperm, and can measure both single and double strand breaks. Unlike the SCSA® test, the Comet® assay may be subject to inter-observer variability and may be less statistically robust as it measures low counts of 50 to 100 sperm cells from each sample.


Instructions for collection of sperm DNA specimens

Sperm DNA Fragmentation is not part of the Comprehensive Semen Analysis, and needs to be requested as a separate test, test code SEXT. Semen samples ideally need to be frozen as soon as possible after liquefaction, but not longer than 60 minutes post-ejaculation. Samples must be snap-frozen for Sperm DNA Fragmentation testing.

If samples are prepared by another laboratory, two cryovials containing not less than 0.25 mls of semen are required. Frozen samples can be sent to TDL, or collected by TDL by arrangement, and must be accompanied with relevant patient details, the sperm count and a GDPR consent form.

A count of a minimum 1 million/ml is required for accurate DNA reporting.