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Montreal--The first report of improved sperm DNA integrity after specific surgical therapy was presented at the AUA annual meeting in San Antonio. Although the cohort was small and the statistical significance slim, the study's authors say the data support the beneficial effect of varicocelectomy on human spermatogenesis.
There is currently no reported treatment for men with high levels of sperm DNA damage.
Data collected and analyzed by Armand Zini, MD, and his teams at the University of Toronto and McGill University, Montreal, were presented by Jason M. Boman, MD, a urology resident at McGill. Dr. Boman said sperm DNA damage is a possible marker for reduced fertility in men, and that infertile men possess a significantly greater percentage of sperm with damaged DNA compared with fertile men. Varicocelectomy appears to improve standard semen parameters, he said, but controversy exists about the true effect of varicocele repair on male fertility.
The retrospective review of couples who presented to infertility clinic identified 37 men who had varicocelectomy for clinical varicocele. Mean patient age was 36 years, and mean duration of infertility was 3.5 years. Most men presented with primary infertility and a unilateral left varicocele.
Semen samples from each of the 37 men were obtained before surgery and 6 months after surgery. DNA damage to the semen was determined by DNA denaturation assay, which also is known as the sperm chromatin structure assay.
All microsurgical varicocelectomies were performed by Armand Zini, MD, senior author of the study, which was conducted when he was at Mount Sinai Hospital in Toronto. Dr. Zini is now an associate professor in the division of urology at McGill University.
"The percentage of spermatozoa with DNA denaturation decreased following varicocelectomy compared to preoperatively: 24.6% versus 27.7%, respectively," Dr. Boman reported.
The 3% reduction in DNA damage after the procedure was statistically significant. But while sperm concentration and the percentages of motile sperm and normal forms increased after varicocelectomy by World Health Organization criteria, that difference did not reach statistical significance.
"At this time, the clinical impact of the 3% reduction is difficult to assess, given our limited understanding of the full clinical implications of sperm DNA damage on reproductive outcomes," Dr. Boman said. "Likely, the impact is modest."
Nevertheless, the results add credibility to the practice of varicocelectomy in that measures of sperm DNA denaturation exhibit a lower biological variability than do conventional semen parameters.
Dr. Boman acknowledged that this non-randomized, uncontrolled study was small, and, as such, the data do not answer the clinical question of whether a varicocele repair improves fertility.
"However, we feel the data do justify proceeding with larger prospective, controlled studies," Dr. Boman concluded.
A member of the audience questioned the significance of this study, given the limitations Dr. Boman had enumerated.
Joel Marmar, MD, professor of surgery and head of the division of urology at Cooper Hospital/University of Medicine and Dentistry of New Jersey, Camden, said most urologists who select patients for varicocelectomy use the WHO standard of less than 20 million sperm/mL, but acknowledged that, due to the variability of analyses, most institutions would want a panel of at least three semen specimens for determining the intrinsic variability of any one patient.
"Having only one sample either before or after surgery, you run the risk of regression towards the mean," Dr. Marmar said.
His criticism was meant to be constructive, he said, and suggested that he thought the study authors "may be on to something with the DNA analysis, but they have to do the study properly."