A possible explanation has been found for frequent infertility in men who undergo a vasectomy reversal operation, researchers at Johns Hopkins Hospital reported today in the New England Journal of Medicine.
Dr. Jonathan P. Jarow and his colleagues have associated the infertility with the formation of fiber-like tissue in the testes caused by the original vasectomy.
The findings by Dr. Jonathan P. Jarow and his colleagues may help explain the discrepancy between the 90% or greater success rate of the microsurgical reconnection procedure and resumed fertility in only 40% to 70% of the men who have the reversal surgery.
Vasectomy is one of the most common forms of male contraception in the world and more than 500,000 men choose to undergo the surgery each year in the United States, according to the authors. Considered a permanent procedure until recently, technical surgical advances have made reoperation feasible. In recent years more vasectomy reversals have been sought, primarily by men who have remarried and again wish to have children.
"Vasectomy should be viewed as a permanent procedure, not a reversible procedure," said Dr. Fray F. Marshall, associate professor of urology at Johns Hopkins Hospital in Baltimore, another of the study's authors. "If people have doubts about it, they shouldn't have it."
Does Not Affect Potency
Marshall stressed that the findings applied only to changes in the anatomy of the testes, and that vasectomy does not affect the hormones responsible for sexuality and potency. The results are "not an excuse not to have a vasectomy," he said.
Vasectomy is usually a five- to 10-minute office procedure performed by urologists. Using a local anesthetic, segments of tubes called the vas deferens, through which the sperm travels after leaving the testes, are removed. After the surgery, sperm continue to be produced, but they are no longer present in the ejaculate.
The vasectomy reversal, called vasovasostomy, restores the function of the vas deferens by reattaching the pieces of the tube that were previously separated. The two- to three-hour specialized procedure is performed in the operating room with the assistance of 12- to 15-fold magnification, according to Marshall. The sutures are smaller than a human hair. Marshall said that thousands of the reversals have been performed since the operation was introduced in the late 1970s.
Tissue Samples Studied
Tissue samples obtained from the testes of a random sample of healthy men undergoing vasectomy reversal were examined under light and electron microscopes and compared to biopsy specimens from a control group of 21 untreated, fertile, healthy, age-matched volunteers. The post-vasectomy patients had a mean age of 36 years and had received their vasectomies an average of more than six years previously.
The authors found a variety of "significant" changes in the testes examined after vasectomy, including a form of scarring, called "focal interstitial fibrosis," and a decrease in mature sperm cells, compared to the healthy controls.
Of the 27 patients for whom follow-up information was available, 24 had a surgically successful vasectomy reversal, and 13 were fertile. Testes of seven of the 11 infertile patients showed interstitial fibrosis, compared to none of the fertile patients. No significant differences between fertile and infertile men were found in post-reversal sperm counts and the other tissue characteristics assessed.
Marshall said that the authors had expected to see more problems with the production of sperm in the infertile men, but because of the small number of patients studied may have been unable to detect additional differences between fertile and infertile men.
Fibrosis, Infertility Link
The study does not explain why fibrosis of the testes is associated with infertility. "I don't think anybody knows," Dr. Charles J. Flickinger of the University of Virginia School of Medicine said in a telephone interview. Flickinger wrote an editorial accompanying the article.
One theory to explain changes in the testes after vasectomy involves a key role for the immune system. Sperm cells and their immature forms are normally not exposed to the immune system. But the disruption caused by vasectomy, which blocks the exit of the sperm from the body in the ejaculate, can result in an immune response to the man's own sperm, according to Flickinger.
Studies of the effects of vasectomy on the male reproductive organs have been much more extensive in animals than men, primarily because of the difficulties of obtaining tissue specimens, he wrote. A great deal of species variability has been demonstrated.
The healthy control patients for the Johns Hopkins study came from the Karolinska Institute in Sweden, where they underwent testicular biopsy, an outpatient procedure done with a local anesthetic, as part of an unrelated drug study, according to Marshall.
"Philosophically, that might be hard to do in this country," he said.