Comparison of Monopolar Electrocoagulation ... - Capital Health

Surg Today (2006) 36:908–913
DOI 10.1007/s00595-006-3254-1
Comparison of Monopolar Electrocoagulation, Bipolar
Electrocoagulation, Ultracision, and Ligasure
Theodore Diamantis 1 , Michael Kontos 1 , Antonios Arvelakis 1 , Spiridon Syroukis 1 , Dimitris Koronarchis 1 ,
Apostolos Papalois 1 , Emmanuel Agapitos 2 , Elias Bastounis 1 , and Andreas C. Lazaris 2
1
First Department of Surgery, “Laiko” General Hospital, National and Kapodistrian University of Athens, Athens, Greece
2
First Department of Pathology, National and Kapodistrian University of Athens, 75 Mikras Asias Str., Goudi, GR-115 27 Athens, Greece
Abstract
Purpose. Hemostasis is a fundamental principle of
surgery. We compared the safety and efficacy of
monopolar electrocoagulation (ME), bipolar electrocoagulation
(BE), Ligasure (LS), a modern bipolar vessel
sealing system, and Ultracision (UC), a system of ultrasound
energy based shears. We also studied the healing
process after their use.
Methods. We used each of the above methods to coagulate
and divide the short gastric vessels of 16 white male
New Zealand rabbits. The animals were killed after 3, 7,
14, or 21 days, and the coagulation sites and the adjacent
gastric wall were examined histologically.
Results. LS and UC achieved complete hemostasis
without any complications. Conversely, ME and BE
often resulted in failed coagulation and perforation of
the neighboring gastric wall from a side thermal injury.
Histologically, LS demonstrated the mildest side thermal
injury and the fastest healing process. We noted
greater thermal injury and inflammatory response after
UC than after LS on days 7 and 14; however, ME and
BE caused the most severe lesions.
Conclusions. LS and UC are clearly the safest and most
efficient methods of coagulation, whereas ME and BE
could cause serious clinical and histological complications.
We found histological evidence that UC
causes a slightly greater inflammatory response than LS,
and the clinical implications of this warrant further
investigation.
Key words Monopolar · Bipolar · Ligasure · Ultracision ·
Hemostasis
Reprint requests to: A.C. Lazaris
Received: June 2, 2005 / Accepted: March 14, 2006
Introduction
The quest for safer and more efficient hemostatic techniques,
both in open and laparoscopic surgery, has provided
us with several new coagulating tools. Two of the
most widely used are Ligasure (LS), an electrothermal
bipolar vessel sealer, and Ultracision (UC), ultrasonic
coagulating shears. These methods are gradually replacing
the older monopolar electrocautery (ME) and bipolar
electrocautery (BE). 1–17 We conducted this study to
investigate the mid- and long-term healing process after
LS and UC, since there is limited information in the
literature. We also compared the efficacy and safety of
all four methods of coagulation.
Materials and Methods
Approval from the Ethical Committee of Animal Care
of the East Attica County was obtained before commencement
of this study. We used 16 white, male New
Zealand rabbits with an average weight of 2.6 kg. All
procedures were performed with the animals under
general anesthesia.
The animals were fasted for 24h preoperatively, and
anesthesia was induced with 35mg/kg ketamine intramuscularly
(i.m.) and 5 mg/kg xylazine i.m. An ear vein
catheter was inserted and 10µg of fentanyl diluted in
2.5 ml of normal saline was injected intravenously (i.v.).
The animals breathed room air spontaneously under
continuous monitoring of the cardiac and respiratory
rate. After placing the animals on an operating table in
the supine position, we made a midline incision and
identified the short gastric vessels; namely, the artery
and vein. The diameter of each vessel did not exceed
1 mm.
We used a Berchtold Electrotom 530 Monopolar
Electrocautery device (Berchtold, Tuttingen, Germany)
to test ME efficiency and safety. The artery and

T. Diamantis et al.: Methods of Coagulation
vein were grasped at the same time between the jaws of
a common pair of non-toothed forceps and the ME was
applied to the forceps. The machine was set to coagulation
mode at 8/10 of the maximum power. To test BE,
we used a Berchtold Electrotom 530 Bipolar Electrocautery
device (Berchtold). The artery and vein were
grasped together between the jaws of the BE forceps
and BE was applied. The device was set at 8/10 of the
maximum power. The standard Valleylab Ligasure
vessel sealing system, consisting of a generator and
a clamp, was used for the LS testing (Valleylab
Healthcare Group LP, Boulder, CO, USA). The artery
and vein were again grasped at the same time between
the jaws of the clamp and energy was started at 50% of
the maximum power. To test ultrasonic coagulation, we
used Ethicon Ultracision with 10-mm forceps (Ethicon
Endosurgery, Johnson & Johnson, Cincinnati, OH,
USA). The artery and vein were grasped separately
between the jaws of the UC forceps and the power was
set at level 4 of the var mode.
After the application of ME, BE, and LS, the vessels
were divided with a pair of scissors. Division of the
vessels was also achieved with the UC forceps. Three to
five pairs of vessels were found in each animal. In
total, 73 pairs of vessels, consisting of an artery and a
vein, were coagulated and divided. ME was used in 20
pairs of vessels, BE in 20, LS in 16, and UC in 17. If
several applications of a hemostatic method could not
control hemorrhage, a hemostatic suture (silk 3–0) was
placed.
After complete control of hemorrhage, the abdominal
incision was closed and the animals were observed
carefully until they recovered from the effects of the
anesthetic agents. After recovery, they were returned to
their cages and remained under close observation until
they were killed with 1g thiopental i.v.
The animals were randomly allocated into four
groups of four. The animals in group A were killed on
postoperative day (POD) 3, those in group B were
killed on POD 7, those in group C were killed on POD
14, and those in group D were killed on POD21.
After death, the stomach, the area of the operation,
and the whole peritoneal cavity were thoroughly investigated.
We recorded the presence of blood, pus, or
other free peritoneal fluid and free or contained perforation
of the stomach. To investigate the side thermal
injury caused by each method, the greater curvature of
the stomach in close proximity to where hemostasis was
applied and the surrounding fibro-fatty tissue were harvested,
cut appropriately and fixed in 10% buffered
formalin solution for 48h. Subsequently, the tissue was
sampled and processed routinely, then embedded in
paraffin. We stained 4-µm-thick sections with hematoxylin–eosin
(H&E) and evaluated them by light
microscopy.
909
The samples were examined histologically by two
pathologists unaware of the type of coagulating method
used and the number of days the animal lived after
the operation. The presence and degree of coagulation
damage, including tissue degeneration and necrosis,
transmural extension of the lesion, mucosal ischemia,
and the degree of secondary inflammation (determined
by the presence of neutrophils) in the subserosal
and muscular layers were taken into account. Features
of the healing process, including collagen formation
and fibroblastic reaction, were recorded. The extent of
the damage was semiquantitatively evaluated by the
depth of the stomach wall involved. The severity
of damage was determined by the level of stomach
wall involvement, from the serosal to the mucosal
layer.
Results
We coagulated and divided 73 pairs of vessels, being
three to five pairs in each animal. Each pair of vessels
consisted of an artery and a vein. ME was used in 20
pairs, BE in 20, LS in 16, and UC in 17. The single use
of ME failed to achieve hemostasis in 5 (25%) of the 20
pairs of vessels. The respective proportions of failure of
the other methods were as follows: for BE 6/20 (30%)
for LS 0/16 (0%) and for UC 1/17 (5.88%). One or more
further applications of the tool or, finally, the placement
of a hemostatic suture, were used for bleeding control.
Despite multiple applications and hemostatic sutures
being placed, the coagulation method was inefficient in
2 (10%) of the 20 ME sites, 2/20 (10%) of the BE sites,
and in none of the LS or UC sites. The overall efficacy
after one or more applications was 18/20 (90%) for ME,
18/20 (90%) for BE, 16/16 (100%) for LS, and 17/17
(100%) for UC (Table 1).
Postoperatively, weight loss and abnormal behavior
were observed in one animal, while the others had an
uneventful postoperative course. Inspection of the abdominal
cavity revealed multiple adhesions around the
area of coagulation, which were most prominent after
ME, less after BE, and minimal after LS and UC. Free
abdominal fluid was seen in the animal that appeared
unwell postoperatively. In this animal, which was killed
on POD 3, a free perforation of the greater curvature of
the stomach was found at the site where ME was used.
Contained perforation sites were also observed in other
animals, being common after ME (4/20, 20%) and less
frequent after BE (2/20, 10%) (Table 1). The orifice of
the perforation was obstructed by fatty tissue, small or
large bowel, or even the spleen.

910 T. Diamantis et al.: Methods of Coagulation
Table 1. Efficacy and safety of the four hemostatic methods
Hemostasis after Hemostasis achieved
a single after one or more Contained Free
Method application applications perforation perforation
ME 15/20 (75%) 18/20 (90%) 4/20 (20%) 1/20 (5%)
BE 14/20 (70%) 18/20 (90%) 2/20 (10%) 0
LS 16/16 (100%) 16/16 (100%) 0 0
UC 16/17 (94%) 17/17 (100%) 0 0
ME, monopolar electrocoagulation; BE, bipolar electrocoagulation; LS, Ligasure; UC,
Ultracision
Table 2. Pathologic findings of the gastric layers at the sites of monopolar electrocoagulation, bipolar electrocoagulation,
ligasure, and ultracision application
ME BE LS UC
Day 3 4/5 (80%) 4/5 (80%) 3/4 (75%) 4/5 (80%)
Mucosa, 1/5 (20%) Submucosa, 1/5 (20%) Muscular, 1/4 (25%) Muscular, 1/5 (20%)
submucosa mucosa subserosa submucosa focally
Day 7 5/5 (100%) 5/5 (100%) 4/4 (100%) 3/5 (60%)
Mucosa Muscular Subserosa Muscular, 2/5
(40%) subserosa
Day 14 4/5 (80%) 3/5 (60%) 4/4 (100%) 3/3 (100%)
Mucosa, 1/5 (20%) Muscular, 1/5 (20%) Subserosa Muscular
submucosa mucosa, 1/5 (20%)
submucosa
Day 21 4/5 (80%) 3/5 (60%) 4/4 (100%) 3/4 (75%)
Mucosa, 1/5 (20%) Muscular, 1/5 (20%) Subserosa Subserosa, 1/4 (25%)
submucosa submucosa, 1/5 (20%) muscular
subserosa
Pathological Findings
On POD 3, tissue samples from the ME and BE sites
were characterized by severe necrotic and inflammatory
lesions. We observed coagulative necrosis of the submucosal
and muscular layers, and the subserosa, with neutrophil
aggregation, vessel wall necrosis, and thrombus
formation, as well as subserosal vascular congestion.
The lesion often involved the mucosa after ME and in
one BE sample from an animal killed on POD 3 (Table
2). On the other hand, tissue from the UC and LS sites
demonstrated minimal lesions extending to the muscular
layer. These necrotic lesions were located mainly in
the subserosa and in part of the muscular layer of the
gastric wall. The submucosa was only affected focally.
On POD 7, the most severe lesions were again observed
in the ME and BE samples. After ME, lesions
were seen throughout the gastric wall, with necrotic
areas in the muscular layer containing neutrophilic
aggregation. Neovascularization was prominent in the
submucosa. After BE, thrombotic vessels were observed
in the subserosa and coagulative necrosis was
evident in parts of the muscular layer, although no lesions
were detected in the submucosa. The lesions after
LS consisted of fibroblastic reaction in the subserosa,
but the outer muscular layer was unremarkable (Fig.
1A). After UC, in addition to a subserosal fibroblastic
reaction, several necrotic areas were noted in the muscular
layer (Fig. 1B) and thrombotic vessels were seen
in the submucosa.
On POD 14, successful tissue repair was achieved
more easily after BE than after ME, the latter demonstrating
mucosal ulceration, fibrinoid necrosis, and
granular tissue formation throughout the gastric wall.
LS and UC resulted in milder damage. The LS lesions
were again noticeable only in the subserosa and consisted
of a moderate fibroblastic reaction (Fig. 2A).
After UC, in addition to the subserosal fibroblastic
reaction, the muscular layer was thinner, probably as a
result of organization of the necrotic areas by connective
tissue (Fig. 2B).
On POD 21, the healing process had replaced much
of the muscular layer in the ME and BE tissue, whereas
in the LS and UC tissue, a residual fibroblastic reaction

T. Diamantis et al.: Methods of Coagulation
911
A
A
B
B
Fig. 1. A Ligasure — day 7. Fibroblastic reaction was seen
in the subserosa without other notable lesions (H&E, ×40).
B Ultracision — day 7. In addition to the fibroblastic reaction
of the subserosa, several necrotic areas were seen within the
muscular layer (H&E, ×40)
was barely noticeable and the integrity of the gastric
wall layers was re-established. The pathologic results
are arithmetically summarized in Table 2.
The depth of each lesion produced by the hemostatic
methods used in the vast majority of specimens is demonstrated
schematically in Fig. 3. This figure clearly
shows that the damage caused by ME was significantly
greater than that caused by LS or UC.
Discussion
To our knowledge, this is the first study to compare
these four methods of hemostasis experimentally at the
same time. The results show the clear superiority of the
new LS and UC systems over the older ME and BE
techniques, but also reveal a difference in the healing
process between LS and UC. ME proved to be the least
Fig. 2. A Ligasure — day 14. Moderate fibroblastic reaction
was limited to the subserosa (H&E, ×40). B Ultracision — day
14. In addition to the subserosal fibroblastic reaction, the
muscular layer was thinned, probably as a result of the organization
of necrotic areas (of day 7) by connective tissue (H&E,
×40)
effective and safe method of hemostasis, producing
various complications and leaving serious histologic
changes. The effects of BE are better than those of ME,
but not as good as those of LS or UC.
We based our evaluation of efficiency on the achievement
of hemostasis intraoperatively. A high percentage
of ME and BE initial applications were not effective,
necessitating re-applications or hemostatic suturing.
ME and BE seemed to have similar efficiency with a
possible superiority of ME, in accordance with previous
reports. 18–20 LS was the most efficient method of hemostasis
12 and UC required re-application in only one
animal. UC demonstrated better efficiency than ME
and BE, in agreement with the report by Kwok et al. 21
The slight superiority of LS over UC in our series
reflects the findings of previous studies. 1,3
Safety is indicated by involvement of the adjacent
gastric wall, either as free or contained perforation or as

912 T. Diamantis et al.: Methods of Coagulation
Fig. 3. Schematic representation of the depth of the lesions
caused by each hemostatic method. The bars refer to the
depth of most lesions in each group. ME, monopolar electrocautery;
BE, bipolar electrocautery; LS, Ligasure; UC,
Ultracision
remarkable histologic evidence of gastric wall thermal
injury. In the present study, ME was the least safe
method of hemostasis, causing contained perforations
in 20% and free perforation of the gastric wall in 5% of
the animals. Thermal injury after ME application has
been described in many studies. 20,22–24 Although BE was
safer than ME, it was not as safe as LS or UC. 25 UC and
LS seemed to be the safest, with no complications seen
in this study. 26,27
Side thermal injury is likely to occur after every
method of coagulation. The ideal technique would be
one that provides excellent hemostatic results and allows
no thermal energy to escape from the area where it
has been strictly applied. Thermal injury of the surrounding
tissue was much more evident after ME and
BE than after LS or UC.
We found that ME causes by far the most damage,
sometimes resulting in gastric perforation. Moreover,
the healing process takes considerably longer and is still
incomplete by the end of the third week. BE produces
less damage and although tissue injury is comparable
with that of ME, the healing process is generally faster,
with less residual damage.
The short-term damage left by LS and UC has been
reported by other investigators. Goldstein et al. reported
that LS and laparosonic shears caused equally
minimal thermal damage on domestic pig ureters. 28
Thermal spread from LS and UC is limited to an area
less than 1.5 mm and 1.6mm beyond the tissue bundle or
vessel, respectively. 29,30 Ultrasonic energy delivered
through a harmonic scalpel has been shown to be safe
and to produce minimal damage to the surrounding
tissues in demanding clinical settings, such as anorectal
mucosectomy for ulcerative colitis. 31 On the other hand,
high-power ultrasonic dissection may result in considerable
heat production and collateral tissue damage, especially
when the activation time exceeds 10 s. 32
We also investigated the long-term healing period
after LS and UC application and found that although
the effects of the two methods appeared similar initially,
a difference emerged between the end of the first and
the end of the second week. The thermal injury produced
after UC application was more severe, manifesting
as a delayed healing process with inflammatory
structures invading the muscular layer. These findings
were constant in almost all the UC sites examined histologically
on PODs 7 and 14. On the other hand, the
healing process after LS application was minimal
throughout the study period and the lesions did not
extend beyond the subserosa. This may indicate less
severe thermal injury, resulting in a milder inflammatory
response.
We studied the “coagulation” and not the “cutting”
mode of ME because the former is used more often by
general surgeons. The “cutting” mode is sometimes
used in the clinical setting when ME is applied between
the jaws of forceps. It is believed to cause less damage to
the tissue than the “coagulation” mode.
In conclusion, our findings suggest that the newer
hemostatic techniques LS and UC are safer and more
effective than the older ME and BE. Despite this, many
surgeons still use ME in conventional operations. Although
LS might cause slightly less thermal injury than
UC, the clinical implications of this need to be investigated
further.
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