However, a U.S. commentator questions the review's study selection and the way it defines infertility.
Fertility experts have long thought that varicoceles, an enlarged group of veins within the scrotum, could be a cause of male fertility problems. Varicoceles occur in 15 percent of all men, and in nearly 40 percent of men undergoing infertility treatment.
Surgery or embolization, a procedure that blocks blood supply to the varicoceles, is often performed in an effort to increase fertility.
"Every year thousands of men are operated on without sufficient scientific evidence that the surgery will have any impact," said Johannes Evers, the lead review author. "There have been dozens of observational studies published showing a positive effect. However, high-quality, randomized trials were not able to confirm these positive conclusions."
The review included eight studies involving 607 men. In addition to the presence of a varicocele, study authors looked at other fertility indicators such as quantity and quality of the man's semen. Pregnancy and live birth were the main outcomes measured. Treatment was either by surgical removal of the varicocele or embolization, where a surgeon inserts a small coil or scarring agent into the vein to block it off.
"This review fails to offer evidence that treatment of varicoceles in men from couples with otherwise unexplained subfertility improves the couple's chances of pregnancy," Evers said. "Treatment of varicoceles in men cannot be recommended. The 'first, do no harm' principal should guide us as long as there is no evidence to the contrary."
Evers is a professor of obstetrics and gynecology at Academisch Ziekenhuis in Maastricht a city in the Netherlands.
The review appears in the latest issue of the Cochrane Library is a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
"My suggestion for patients is to check for other factors that might impair fertility before treating the varicocele," Evers said. "Varicoceles do not seem to decrease fertility, or at least removing them doesn't seem to help. Don't concentrate on the wrong issue when there are other more important fertility factors present."
Joel Marmar, M.D., a professor of urology at the Robert Wood Johnson Medical School in Camden, New Jersey is concerned that what he calls a "clinical hodgepodge of therapy" makes the results of the review confusing.
"Not everyone with a varicocele is going to be infertile," Marmar said. "Treatment guidelines written by the American Urological Association and The American Society of Reproductive Medicine suggest that only those with a varicocele that the physician could feel (palpable) and a documented sperm abnormality should be treated. This review had studies that included men with normal semen parameters and very small or subclinical varicoceles."
Using the more stringent guideline criteria for infertility makes a difference, Marmar said.
"Looking at all eight [review] studies, the odds ratio that treatment would be successful was 1.1 [indicating no benefit from the treatment]," he said. However, the results changed when the reviewers looked at a subset of three studies that met guideline criteria, Marmar said. "When including only those men who had palpable varicoceles and semen abnormalities, the odds ratio doubled. These improved results were reported despite a variety of therapies being used."
Including both surgery and embolization in the analysis further confused the outcomes as they related to treatment of fertility issues, according to Marmar: "These techniques may have different success and failure rates. When developing a study design, it may not be appropriate to mix treatment options together."