Technique modification may improve vasectomy effectiveness. (Contraceptive Update).

Physicians who use simple ligation and excision to perform male sterilization, or vasectomy, should strongly consider modifying their surgical technique to include fascial interposition, recent research shows.

Preliminary results from a vasectomy study in seven countries conducted by FHI and EngenderHealth, based in New York, NY, indicate that including fascial interposition leads to a more rapid decrease in sperm counts than performing only simple ligation (tying) and excision (cutting) of the vas deferens, each of two tubes that carry sperm from the testes. Fascial interposition involves pulling the fascial sheath covering the vas over one severed end and sewing it shut to create a natural tissue barrier. This extra step may further improve the effectiveness of this male contraceptive method.

"Vasectomy is safer, quicker, and easier to perform than female sterilization, and it is already highly effective," says Dr. David Sokal, associate medical director at FHI who led the research. "But efforts to make vasectomy even more effective are important in order to increase confidence in the method and to encourage its wider use."

During the study, when fascial interposition was used with ligation and excision, about 93 percent of men had reached a low sperm count (less than 100,000 sperm per milliliter of semen) by 22 weeks after surgery compared to 81 percent of men without fascial interposition. A man's normal sperm count is above 20 million per milliliter.

Persistence of sperm in some men who underwent ligation and excision alone had already been observed in an FHI study conducted in Mexico in the late 1990s. Researchers found that, in more than 10 percent of men undergoing ligation and excision, substantial numbers of sperm may persist in semen for many months.

In Nepal, persistence of sperm one to four years after vasectomy (usually involving simple ligation and excision) was documented in 2.3 percent of some 1,000 men, in a study conducted in 2,000 by FHI in collaboration with the Ministry of Health of Nepal. The pattern of sperm counts among men with persistent sperm in their semen suggested that recanalization had occurred; that is, sperm had temporarily or permanently found a way through the healing vasectomy site. Notably, fascial interposition may increase the effectiveness of vasectomy by preventing such recanalization.

The risk of pregnancy is probably higher among women whose partners take longer to reach a low sperm count. The FHI/EngenderHealth study did not examine pregnancy rates. But researchers conducting the study in Nepal estimated that, among 1,000 couples using ligation and excision vasectomy for family planning, 17 women would become pregnant during the first year after the procedure. In contrast, in the United States, where vasectomy procedures are different, semen testing is routinely available, and couples choosing the method are older, 1.5 women among 1,000 couples would be expected to become pregnant during the first year after the procedure.

METHODS VARY

Throughout the world, different vasectomy methods are practiced. Most if not all can be done with or without the use of fascial interposition. In developing countries, ligation and excision is the most common method. In the United States and other high-resource countries where vasectomy is popular, cautery (burning the inside of the ends of the vas) and/or metal clips, often with fascial interposition, are the most common techniques.

Some experts consider cautery to be the best method of closing the vas. More research, however, is needed to evaluate the method and to determine the feasibility of its use in low-resources settings For example, relatively inexpensive, hand-held cautery devices powered by AA alkaline batteries are commonly used in a number of developed countries, but have not been studied in low-resource settings.

Regardless of the procedure used, cautions Dr. Sokal, it is important for couples to understand the slight risk of failure.

"After vasectomy, where semen testing is available, men should get tested," he says. "Where semen testing is not available, couples are usually advised to use backup contraception for 12 weeks. This waiting period is needed to allow sperm that are downstream from the vasectomy site to be flushed out of the vas. However, even if men follow these instructions, there is a small risk of pregnancy. So, if the partner of a vasectomized man later becomes pregnant, one should assume that the pregnancy was a result of a failed vasectomy rather than infidelity."

The ongoing FHI/EngenderHealth research, which began in 1999 and is supported in part with funds from the U.S. Agency for International Development, is being carried out in Brazil, El Salvador, Nepal, Mexico, Panama, Sri Lanka, and the United States. Final analysis of the study will be done after all men have completed follow-up.

These and other recent studies on vasectomy effectiveness were presented in 2001 at a meeting of experts cosponsored by FHI and EngenderHealth. A summary of this meeting can be found at http://www.fhi.org/en/fp/fpother/conference/vascet/vasectomymtg.html.

In the recent study conducted in seven countries, all procedures used the no-scalpel method of vasectomy (NSV), which affects how the surgeon approaches the vas. NSV can be used with various methods of blocking the vas, and has been shown to have fewer side effects, although it can be more difficult for surgeons to learn than the traditional approach using a scalpel.