AFRO-NETS> Pregnancies More Common than Expected after Vasectomy

[David Hock <DHock@fhi.org>]

Pregnancies More Common than Expected after Vasectomy
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KATHMANDU, Nepal - A recent study of Nepalese men who had been ster-
ilized with a form of vasectomy (male sterilization) widely used in 
developing countries has found that the pregnancy rate is higher than 
previously thought. The study included 1,052 men who had had a vasec-
tomy between one and four years ago.

The study, undertaken by Family Health International (FHI), in col-
laboration with the Ministry of Health, His Majesty's Government 
(HMG) of Nepal, estimated a first-year pregnancy rate of 17 per 1,000 
among wives of men having ligation and excision vasectomies. That is, 
among 1,000 couples using this particular form of vasectomy for fam-
ily planning, 17 women would become pregnant during the first year 
following the procedure. "This contrasts with an estimated pregnancy 
rate of 1 to 2 per 1,000 vasectomies in the United States, where dif-
ferent vasectomy procedures are typical and where couples are much 
older," reported Hanif Nazerali, FHI's principal investigator for the 
study.

Compared with other forms of family planning, the vasectomy procedure 
used in Nepal is still quite reliable. For example, for couples using 
the Copper T intrauterine device, considered a very effective contra-
ceptive method, approximately 8 women per 1,000 users will experience 
an unintended pregnancy during the first year. And for couples using 
condoms, approximately 30 to 140 women among every 1,000 become preg-
nant during the first year.

"This study is unique in that it is the first time that we have at-
tempted to evaluate the effectiveness of vasectomy in a large sample 
of men from diverse areas in Nepal," says Dr. Kalyan Raj Pandey, a 
research member of the study, President of the Nepal Medical Associa-
tion and advisor to the Ministry of Health.

"The results of the study in Nepal are not very different from what 
we are finding in some other developing countries when simple liga-
tion and excision are used," reports Dr. David Sokal, a medical di-
rector at Family Health International. "While a vasectomy procedure 
is an excellent method of family planning, it's important that cou-
ples understand there is a small but real possibility of pregnancy 
after vasectomy."

"The study findings have important implications for counseling, fol-
low up and clinical training," notes Dr. Laxmi Raj Pathak, another 
member of the research team and director of the Ministry of Health's 
Family Health Division.

Vasectomy is a permanent form of contraception in which the vasa 
deferentia - the tubes that carry sperm from the testes - are oc-
cluded (closed), either by ligation or other means. In developing 
countries, ligation (tying) and excision (removal) of a small length 
of the vas is the most common method of occlusion. In the United 
States and other high-resource settings where vasectomy is popular, 
cautery (burning) or metal clips are the most commonly used methods 
to occlude the vas.

Family planning handbooks typically describe vasectomy as nearly per-
fect, better than 99 percent effective at preventing pregnancy. How-
ever, different ways of performing a vasectomy may result in slightly 
different pregnancy rates.

In a related study, specifically designed to compare two different 
vasectomy techniques, preliminary results being released later this 
month show conclusively that sperm counts decrease more rapidly when 
a surgical technique known as fascial interposition is added to the 
simple ligation and excision technique. That study was conducted in 
Nepal and six other countries. Most of the men in the study announced 
today in Nepal had undergone vasectomy using simple ligation and ex-
cision, but without fascial interposition. Fascial interposition is a 
procedure in which the sheath covering the vas is pulled over one 
severed end and sewn shut to create a natural tissue barrier. The 
seven-country study looked at multiple sperm counts in each man, 
rather than pregnancy rates.

In the study reported today, researchers contacted men who had had a 
vasectomy one to four years ago, and asked each of them to provide a 
single semen sample for laboratory analysis. The men were also asked 
whether their wives had become pregnant. The men in the study were 
chosen from over 30,000 men who had had vasectomies between 1996 and 
1999. The four Hill Districts of Bhojpur, Doti, Ramechhap and Tanahu 
were chosen randomly to represent the Development Regions. A propor-
tionate sample of men was then selected randomly from within these 
districts. About 75 percent of vasectomies performed in Nepal are 
done in the Hill Region.

Twenty-three men, or 2.3 percent, still had sperm in their semen, and 
38 men reported that their wives had become pregnant during the years 
since their husband's vasectomy. Pregnancies were more common among 
the younger women in the study. Eight of the pregnancies occurred 
within three months of the vasectomy, before a vasectomy is consid-
ered to be effective. A life-table calculation gave an estimate of a 
cumulative pregnancy rate of 4.2 percent at the end of three years 
(42 among every 1,000 women) or about 1 percent per year.

"It is quite possible that the pregnancy rate following vasectomy in 
the United States is an underestimate," said Hanif, FHI's principal 
investigator. "If couples believe that vasectomy is 100 percent ef-
fective, a subsequent pregnancy would infer infidelity, and may go 
unreported. We would need systematic follow-up, with counseling, to 
improve our estimates."

Most of the pregnancies reported in Nepal were probably due to re-
canalization - the body healing itself - rather than surgical errors. 
Also, most couples in this study were relatively young compared to 
couples having vasectomies in the United States and other developed 
countries, which means they would be more fertile than older couples, 
and would remain fertile for more years after vasectomy than older 
couples. The process of recanalization can begin when sperm from the 
open ends of the vas leak out and cause a mild inflammation. This re-
sults in a condition known as a sperm granuloma, which is part of the 
body's healing process. A granuloma is made up of white blood cells 
and other cells involved in the body's healing process. The healing 
process can lead to the formation of a honey-combed "bridge" that can 
sometimes connect the two severed ends. Viable sperm can then cross 
and make their way to the other end. 

Recanalization is often not a permanent condition. Often, the 
"bridge" will eventually solidify as part of the healing process, and 
scar tissue (fibrosis) will close off the recanalization. Simple 
ligation and excision appears more likely to lead to recanalization 
than other vasectomy methods.

In Nepal, where semen testing is generally not available, men are ad-
vised to wait 12 weeks before relying on their vasectomy. Until that 
time, couples are advised to use other contraceptive methods, such as 
condoms.

This study included two special features: (a) rigorous quality con-
trol of the semen testing; and (b) Internet-based data entry. Semen 
samples obtained in the Hill Districts of Nepal were preserved and 
analyzed in Kathmandu, and then results were validated by a U.S. 
laboratory. To facilitate data collection and analysis, this study 
used an Internet link for data entry, from Kathmandu to FHI's office 
in North Carolina, USA. This was the first study that FHI conducted 
using the Internet in this way.

This study was supported in part with funds from the U.S. Agency for 
International Development.

For more information, please contact:

Dr. Shyam Thapa 
Family Health International 
Kathmandu, Nepal 
Tel: +977-1-245-325, 245-919

Mr. Nash Herndon 
Family Health International 
Research Triangle Park, NC, USA 
Tel: +1-919-544-7040, ext 224 
mailto:nherndon@fhi.org

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