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 2000
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-resource
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 is available.
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.
– Kim Best
For more information, visit Family Health International's Website at www.fhi.org
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