Fertility and sperm quality are linked. One important indicator of sperm quality is the magnitude of sperm DNA integrity and maturity: The more mature and intact the sperm, the better their overall quality.
As sperm mature during the course of their development, the chromatin of their DNA condenses. If the sperm is immature, however, then their chromatin will abnormally condense. Also, oxidative stress due to free radicals probably damages the DNA and cause breaks in the DNA strand. Determining the extent of these structural defects in the DNA reveals the extent to which the sperm have successfully matured and remained intact, thereby evaluating their quality.
The SDI is necessary because sperm quality indicators go beyond those tested for during standard semen analysis (sperm concentration, motility and morphology). Specifically, SDI measures DNA damage and sperm maturity, and is reported as the DNA fragmentation (damage) index (DFI) and high DNA (maturity) staining (HDS).
Although the exact mechanism by which damaged or immature sperm DNA affects pregnancy outcome is not known, the correlation is strong, making SDI a valuable test for all those undergoing fertility treatment regimens such as in vitro fertilization.
SDI is highly recommended for the male partners of couples who exhibit:
A history of unexplained infertility
Poor embryo quality after in vitro fertilization (IVF)
Implantation failure after IVF
Recurrent chemical or unexplained pregnancy losses, or
Recurrent early spontaneous abortions
The Sperm DNA Integrity Test (SDI) takes advantage of the metachromatic features of Acridine Orange (AO), a DNA probe, and the principles of flow cytometry.
Specifically, the test measures the susceptibility of DNA to denaturation in situ following low pH treatment. Sperm with normal mature chromatin structure do not demonstrate DNA denaturation. Consequently, the AO that intercalates into dsDNA (normal) fluoresces green, while the AO associated with ssDNA fluoresces red.
Interpretation of SDI Test Results:
Damaged DNA in the single sperm cell that fertilizes an oocyte can have a dramatic negative impact on fetal development and offspring health.
Results of control group studies with the current protocol: