A comparison of vas occlusion techniques: cautery more effective than ligation and excision with fascial interposition
A comparison of vas occlusion techniques: cautery more effective than ligation and excision with fascial interposition
David Sokal 2
Belinda Irsula 2
Mario Chen-Mok 2
Michel Labrecque 1
Mark A Barone 0
0 EngenderHealth , 440 Ninth Avenue, New York, NY 10001 , USA
1 Department of Family Medicine, Laval University , Quebec City , Canada
2 Family Health International , PO Box 13950, Research Triangle Park, NC 27709 , USA
Background: Vasectomy techniques have been the subject of relatively few rigorous studies. The objective of this analysis was to compare the effectiveness of two techniques for vas occlusion: intraluminal cautery versus ligation and excision with fascial interposition. More specifically, we aimed to compare early failure rates, sperm concentrations, and time to success between the two techniques. Methods: We compared semen analysis data from men following vasectomy using two occlusion techniques. Data on intraluminal cautery came from a prospective observational study conducted at four sites. Data on ligation and excision with fascial interposition came from a multicenter randomized controlled trial that evaluated the efficacy of ligation and excision with versus without fascial interposition. The surgical techniques used in the fascial interposition study were standardized. The surgeons in the cautery study used their customary techniques, which varied among sites in terms of type of cautery, use of fascial interposition, excision of a short segment of the vas, and use of an open-ended technique. Men in both studies had semen analyses two weeks after vasectomy and then approximately every four weeks. The two outcome measures for the analyses presented here are (a) time to success, defined as severe oligozoospermia, or <100,000 sperm/mL in two consecutive semen analyses; and (b) early vasectomy failure, defined as >10 million sperm/mL at week 12 or later. Results: Vasectomy with cautery was associated with a significantly more rapid progression to severe oligozoospermia and with significantly fewer early failures (1% versus 5%). Conclusion: The use of cautery improves vasectomy outcomes. Limitations of this comparison include (a) the variety of surgical techniques in the cautery study and differences in methods of fascial interposition between the two studies, (b) the uncertain correlation between sperm concentrations after vasectomy and the risk of pregnancy, and (c) the use of historical controls and different study sites.
Vasectomy techniques have been the subject of relatively
few rigorous studies. The Royal College of Obstetricians
and Gynecologists  noted that more research is needed
to compare different methods of vasectomy. Experts have
recommended the use of fascial interposition or cautery
, cautery with clips , and cautery with fascial
We have shown in a randomized controlled trial that
fascial interposition can reduce failure rates by about half
when the occlusion method is suture ligation with vas
excision . However, the failure rates defined by semen
analyses in that study were relatively high, with a failure
rate of 5.7% even in the fascial interposition group.
At an experts' meeting organized by Family Health
International (FHI) and EngenderHealth in April 2001, experts
reviewed data on vas occlusion techniques, including the
preliminary pooled results from the randomized
controlled trial of fascial interposition mentioned above. Given
the apparently high rate of vasectomy failures in that
study, the experts recommended that an observational
study be done to assess sequential sperm concentrations
after vasectomies with cautery to see if there was a
qualitative difference between sperm concentrations after vas
occlusion by cautery and sperm concentrations after
occlusion by ligation and excision. Some participants
suggested that if such a study showed a clear difference in the
rate of success or the frequency of apparent
recanalizations between cautery and ligation and excision with
fascial interposition, then this might provide sufficient
evidence for service providers to consider switching to the
use of a cautery technique .
Based on that recommendation, we conducted an
observational study of vasectomy by cautery  and then
conducted this comparative analysis. Even if some researchers
decide that additional research is needed, the data from
this comparative analysis should provide a strong basis
for planning further research. The objectives of the
analysis presented here were to compare early failure rates,
sperm concentrations, and time to success for vas
occlusion by ligation and excision with fascial interposition
versus those for vas occlusion by cautery.
The methods of the fascial interposition and cautery
studies have been previously described [4,6]. In brief, the
fascial interposition study involved eight sites in seven
countries. It was a randomized controlled trial comparing
two occlusion techniques: ligation and excision with
versus without fascial interposition. All surgeons used the
no-scalpel approach to the vas and a standardized
occlusion technique. The vas was occluded using two silk
sutures, and an approximately 1-cm segment of vas
between the ligatures was excised. For the fascial
interposition technique, a suture was used to contain the
testicular end of the vas inside the fascial sheath; the prostatic
end remained outside . The study was halted following
a planned interim analysis that demonstrated a clear
benefit from the use of fascial interposition . Of 419 men
who had fascial interposition in that study, 410 were
included in this comparative analysis. Nine men were
excluded because of lack of follow-up data.
The cautery study involved four sites in four countries. It
was designed to estimate the effectiveness of cautery as
currently performed and to describe the trends in sperm
counts after vas occlusion by cautery. The surgeons used
their customary cautery occlusion techniques, which
differed among the sites. At two sites, surgeons used
electrocautery without fascial interposition: one with and one
without excision of a short segment of the vas. At the other
two sites, they used thermal cautery with fascial
interposition: one with and one without an open-ended technique
and excision of a short segment of the vas. Three sites used
the no-scalpel approach to the vas. Graphic depictions of
the four methods used have been published . Of 400
men enrolled, 389 are included in this comparative
analysis. Eleven men were excluded because of lack of
Follow-up and semen analysis methods
Both studies included frequent semen analyses, beginning
at two weeks after vasectomy. In the fascial interposition
study, subsequent semen analyses were conducted every
four weeks until a man had provided two consecutive
azoospermic specimens, was declared a vasectomy failure,
or reached the end of study follow-up at 34 weeks. In the
cautery study, after the first sample at two weeks,
subsequent semen analyses were conducted at weeks 5, 8, 12,
16, 20, and 24, regardless of semen analysis findings. In
both studies, participants were asked to record all
ejaculations between semen analyses on a wallet-sized card,
which they gave to study personnel at each follow-up visit.
Semen analyses methods for both studies were based on
World Health Organization recommendations, but the
methods differed somewhat between the two studies.
Freshly collected semen was examined in the fascial
interposition study, and data were obtained on sperm
concentration, motility, and viability. For the cautery study, two
of the four sites did not routinely collect fresh specimens,
so semen analysis data from those two sites were limited
to sperm concentrations. Therefore, for this comparative
analysis, we did not consider sperm motility as an
outcome measure. In addition, specimens showing
azoospermia or very low sperm concentrations were centrifuged in
the fascial interposition study but not in the cautery study.
During both studies, the laboratories conducted periodic
In both studies, we used frequent semen analyses rather
than pregnancy as the vasectomy effectiveness outcome
measure, to minimize the risk of pregnancy, sample size,
and study duration. Vasectomy success is commonly
defined as two azoospermic specimens . However,
small numbers of nonmotile sperm may persist for many
months in some men. Surgeons' experience  and
guidelines recently published by the British Andrology Society
 suggest that low concentrations of nonmotile sperm
(<100,000 sperm/mL) are of less concern than higher
concentrations. We found in the fascial interposition
study  that severe oligozoospermia (<100,000 sperm/
mL) was a more robust measure of success than was
azoospermia, at least for research purposes. In both
studies, men of different ages tended to reach severe
oligozoospermia at about the same time, but older men took
longer to reach azoospermia than did younger men.
Consequently, we used two definitions for vasectomy
success for this comparative analysis. Our primary definition
of success was severe oligozoospermia, defined as
<100,000 sperm/mL in two consecutive specimens taken
at least two weeks apart. Our alternate definition of
success was the occurrence of two consecutive azoospermic
specimens taken at least two weeks apart, with no
subsequent samples showing sperm concentrations of 100,000
sperm/mL or higher. Motility was not considered, for
reasons mentioned earlier. The date of success was the date
of the first of the two oligozoospermic or azoospermic
For early failure, we used a criterion of >10 million sperm/
mL at week 12 or later, regardless of motility. This is an
adaptation of Alderman's criteria specifying 5 million
motile sperm/mL or more as evidence of "overt failure"
. This definition is different from the definitions of
failure used by each of the two studies, but it was
necessary for a comparative analysis because some sites in the
cautery study did not measure sperm motility. Thus, the
failure rates reported here may differ slightly from the
failure rates reported by each study. In addition, to avoid bias
from the two studies' different lengths of follow-up, we
included semen analysis data from the fascial
interposition study through only 26 weeks of follow-up.
The data collection forms, study monitoring, and
laboratory quality-control procedures were similar for both
studies, though only one research site was common to
both. Both studies were organized and managed by
researchers and staff at FHI and EngenderHealth, and
both received approval from FHI's institutional review
Kaplan-Meier product-limit estimates of the probabilities
of severe oligozoospermia, at each scheduled week of
follow-up through week 24, and their 95% confidence
intervals (CIs) were produced overall, by study group (i.e.,
fascial interposition and cautery), and by study group and
age group (i.e., <35 years and 35 years and older). Peto's
standard error  was used to compute the 95% CIs. The
Kaplan-Meier probabilities were compared between the
study groups using a two-sided log-rank test with an alpha
of 0.05. Given that the participants in the fascial
interposition study had a longer follow-up period than the
participants in the cautery study (34 versus 24 weeks), the
information on the fascial interposition participants was
censored at the 26-week visit for the purpose of this
The comparison of failure rates between the two study
groups was based on a Fisher exact test with a two-sided
alternative hypothesis and an alpha of 0.05. In addition,
a logistic model was fit to estimate an age-adjusted odds
ratio of the failure rates and its 95% CI.
Unlike in the cautery study, participants in the fascial
interposition study were discontinued after azoospermia
was confirmed or after vasectomy failure was declared.
Therefore, for the purpose of comparing the distribution
of the participants in the different sperm concentration
categories by week of follow-up, we kept azoospermic
cases in the azoospermic category for all follow-up weeks
after their discontinuation due to confirmed
azoospermia. Similarly, we kept participants with a declared
vasectomy failure in the sperm concentration category that they
were in at the moment of discontinuation, for all
subsequent follow-up weeks.
Detailed results for the two studies have been reported
[4,6]. We report here the results of the comparison of the
semen analysis data from the two studies.
Baseline population data
Among the baseline population characteristics (Table 1),
age distribution was somewhat different between the two
studies, with a younger population in the fascial
interposition study. Marital status, number of children, use of
condoms, and years of education were similar between
the two studies.
Analysis of early failures
We found significantly fewer early failures in the cautery
study than in the fascial interposition group from the
Ligation and excision with fascial
* One "years of education" value was missing for the fascial interposition group.
randomized controlled trial: 1.0% (4/389) versus 4.9%
(20/410) (p = 0.0014 by the Fisher exact test). The
adjusted odds ratio was 4.8 (95% CI, 1.6–14.3),
indicating nearly a five-fold higher risk of early failure in the
fascial interposition study than in the cautery study. No
significant age effect was detected (data not shown).
The distribution of sperm concentrations by week is
shown for the two studies (Figure 1). The difference in
early failures can be appreciated by examining the
percentages of men with high sperm concentrations. In the
fascial interposition study, the percentage of men with
sperm counts of 10 million or more stayed about the same
from 6 to 26 weeks. However, in the cautery study, the
percentage decreased dramatically from 5 to 8 to 12
weeks. This difference was probably due to
recanalizations, which become apparent in the first 6 to 10 weeks
after the procedure.
Time to success
Life-table analyses of time to success showed that the
participants in the cautery study reached severe
oligozoospermia significantly more rapidly than did those in the fascial
interposition study (p = 0.0049) (Figure 2). Ninety-seven
percent of the men in the cautery study had reached
success by 12 weeks, while only 91% in the fascial
interposition study had reached success by 14 weeks. The analyses
of the data stratified by age group showed similar results
(data not shown). Using the time to azoospermia
outcome, the difference between the two groups was also
significant (p < 0.0001) (data not shown).
The difference in the observed failure rates suggests that
vas occlusion techniques that include cautery are
significantly more effective than ligation and excision plus
fascial interposition, at least based on semen analysis. We
believe that most of the failures in the fascial interposition
group were due to early recanalizations within the first
two to three months after vasectomy (data not shown).
Possible explanations for the surprisingly high failure rate
among the fascial interposition group have been
previously presented and discussed .
Recent reports suggest that pregnancy rates may be higher
in low-resource settings, where semen analysis is usually
not available and where most vasectomies are done by
ligation and excision [12,13]. The use of cautery devices
may have the potential to reduce failure rates in
Which cautery technique is best?
When a ligation and excision technique is used, we have
shown that fascial interposition provides an important
improvement in effectiveness . The addition of fascial
tFDiioigsnutr(ielbeu1ftt)iovnerosfusspcearumtecroyn(creignhttr)ations by week after vas occlusion by ligation and excision with fascial
interposiDistribution of sperm concentrations by week after vas occlusion by ligation and excision with fascial interposition (left) versus
pFCoiugsmuitriueolna2t(ivdeasphreodbalibnieli)ty of vasectomy success by week: vas occlusion by cautery (solid line) versus fascial
interCumulative probability of vasectomy success by week: vas occlusion by cautery (solid line) versus fascial interposition (dashed
line). Success was defined as severe oligozoospermia (i.e., <100,000 sperm/mL).
interposition may be less important when cautery is used
as the occlusion method, but this study was not designed
to answer that question.
Schmidt was a pioneer in the use of cautery for vasectomy.
His preferred technique was thermal cautery of about 5
mm of each end of the vas, combined with fascial
interposition and no excision . Two of the sites in the
observational cautery study used techniques very similar to
Schmidt's technique. The other two sites used
electro-cautery without fascial interposition, an approach that has
been used for many years at the Elliot-Smith Clinic in
Oxford  and similar to one used for many years by
Marie Stopes clinics with excellent results . Little
evidence is available to support one type of cautery over
another. Schmidt  preferred thermal cautery to
electro-cautery based on histological examination of
specimens at vaso-vasostomy, and Li  found a lower failure
rate with thermal cautery than with electro-cautery, but
the difference in Li's study was not statistically significant.
The length of the vas segment that is cauterized can vary
by the type of cautery. In the United States and Canada,
marketed thermal cautery "vasectomy tips" have a
functional length of about 0.8 cm, so it would be difficult to
cauterize more than 1 cm of each end. The cautery tip of
the Sturgeon cautery device used by Schmidt was 0.5 cm
long. However, the tips available for electro-cautery
devices are much longer, which could permit
cauterization of longer segments of the vas and potentially cause
more difficulty in the event of a request for reversal.
Since several reports suggest that the combination of
thermal cautery plus fascial interposition is one of the most
effective methods available , this procedure can be
recommended with few reservations. However, there is at
least one other reason to consider the inclusion of fascial
interposition in the vasectomy procedure, especially in
low-resource settings. If providers in low-resource settings
adopted a cautery technique, cautery instruments could
occasionally become unavailable for various reasons. In
those cases, a provider might want to be able to perform
fascial interposition as part of a ligation and excision
Schmidt suggested that cautery should not be combined
with suture or clip ligation of the vas . He noted that
while blood vessels will thrombose after ligation, the vas
will remain open. Thus, using a ligature in addition to
cautery could reduce the value of cautery by causing
necrosis of some or the entire cauterized end, potentially
reducing the benefit from cautery. None of the cautery
techniques in this study included the use of ligatures or
clips on top of a cauterized vas.
Limitations of this comparison include (a) the variety of
vas occlusion techniques used in the cautery study and
differences in methods of fascial interposition between
the two studies, (b) the uncertain correlation between
post-vasectomy sperm concentrations and the risk of
pregnancy, (c) the lack of sperm motility data and
centrifugation for the cautery study, and (d) the use of different
study sites and surgeons in the two studies. The difference
in time to vasectomy success could in part be related to the
lack of centrifugation in the cautery study. However, the
difference in centrifugation between the two studies
would not have affected the detection of early failures,
especially since the cautery study gathered semen samples
throughout the 24-week follow-up period (i.e., men
continued providing semen samples even after they reached
azoospermia). Another potential limitation of this
comparison was the difference in follow-up schedules
between the two studies.
In addition, other factors could have an unknown impact
on the comparability of the data. Even though the results
are encouraging for the use of cautery in vasectomy, we
have to be cautious about making definitive statements
based on this nonrandomized comparison.
Future vasectomy research
Results from this comparative analysis suggest that cautery
may be a more robust and less technique-dependent
method than is fascial interposition. However, additional
research would be useful to directly compare the
effectiveness of the following standardized techniques in a
randomized controlled trial: cautery without fascial
interposition, cautery with fascial interposition, and
ligation and excision with fascial interposition. Additional
research would also be of interest to compare an
openended procedure with a closed-end procedure. Several
investigators have suggested that leaving the testicular end
open reduces post-vasectomy pain, but no randomized
controlled trials have examined this issue [1,18].
We compared data from two prospective multicenter
studies conducted using similar methodologies. We found
that the use of cautery as part of the vasectomy procedure
significantly reduced vasectomy failure rates compared
with ligation and excision plus fascial interposition as part
of the procedure. It is unclear from our results and those
of others whether fascial interposition used with cautery
improves vasectomy success rates when compared with
The authors declare that they have no competing interests.
DS participated in the conception, design and analysis of
the study, and drafted the manuscript. BI participated in
the conception, design, and analysis of the study, and was
primarily responsible for managing the study
implementation. MC participated in the design of the study and was
primarily responsible for the statistical analysis. ML
participated in the conception, design and analysis of the
study. MB participated in the conception, design,
management and analysis. All authors reviewed and approved the
The authors would like to thank the clinical investigators and study
coordinators for the two studies whose work formed the basis of this
comparison. Partial support for this work was provided by FHI with funds from the
U.S. Agency for International Development (USAID) Cooperative
Agreement # CCP-A-00-95-00022-02, and by EngenderHealth with funds from
the USAID Cooperative Agreement # HRN-A-00-98-00042-00, although
the views expressed in this article do not necessarily reflect those of FHI,
EngenderHealth, or USAID.
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