1. © 2008 BC Decker Inc ACS Surgery: Principles and Practice
5 GASTROINTESTINAL TRACT AND ABDOMEN 29 INTESTINAL ANASTOMOSIS — 1
29 INTESTINAL ANASTOMOSIS
Neil J. Mortensen, MD, and Shazad Ashraf, MD
The creation of a join between two bowel ends is an operative that of collagenolysis. After surgery, degradation of mature
procedure that is of central importance in the practice of collagen begins in the first 24 hours and predominates for the
a general surgeon. Despite the potentially disastrous conse- first 4 days. This is caused by the upregulation of matrix
quences that can arise from leakage of an intestinal anasto- metalloproteinases (MMPs), which are an important class
mosis, joining bowel segments is one of the procedures that of enzymes involved in collagen metabolism.10 This family
junior surgeons often perform in the emergency setting. With includes 20 zinc-dependent endopeptidases, among which is
proper supervision and appreciation of fundamental concerns, collagenase (MMP-1).10 In vivo use of MMP inhibitors has
however, there is little difference between the outcomes of been found to increase the strength of intestinal anastomoses
anastomoses performed by trainees and those performed by by up to 48% at postoperative day 3, which suggests that
established surgeons.1 these enzymes may be important in determining the risk of
To minimize the risk of potential complications, it is leakage.11 Sepsis is thought to increase the level of transcrip-
imperative to adhere to several well-established principles tion and activity of these enzymes, thereby potentially leading
[see Table 1]. The main ones relate to the creation of a to problems in the early postoperative period. In an animal
tension-free join with good apposition of the bowel edges in model where bacterial peritonitis was induced, increased
the presence of an excellent blood supply.2 The importance MMP levels were seen on postoperative day 3, coinciding
of surgical technique is underscored by the wide variations of with a fall in the bursting pressure.10 However, no increase in
anastomotic leakage rates among surgeons.3 anastomotic dehiscence was found in comparison with the
The frequency of anastomotic leakage ranges from 1 to control group. By postoperative day 7, collagen synthesis
24%.4–6 The rate of leakage is generally considered to be becomes the dominant force, particularly proximal to the
higher for elective rectal anastomoses (12 to 19%) than for anastomosis. After 5 to 6 weeks, there is no significant
colonic anastomoses (11%).7–9 The consequences of postop- increase in the amount of collagen in a healing wound or
erative dehiscence are dire and include peritonitis, blood- anastomosis, though turnover and thus synthesis are exten-
stream infection, further surgery, creation of a defunctioning
sive. The strength of the scar continues to increase for many
stoma and death. A threefold rise in mortality was seen (from
months after injury.
7% to 22%) in the St. Mary’s Large Bowel Cancer Project,
The cross-linking between collagen fibers and their orien-
when anastomotic leakage occurred.7 Also other problems
tation are the major factors that determine the tensile strength
encountered include a significant increase in hospital stay,
of tissues. Bursting pressure is used as a quantitative measure
and there is a proportion of patients who do not go on to have
to grade the strength of an anastomosis in vivo. This pressure
their stomas reversed.4
has been found to increase rapidly in the early postoperative
This chapter is divided into three broad sections. The first
period, reaching 60% of the strength of the surrounding
discusses factors that influence intestinal anastomotic healing.
bowel by 3 to 4 days and 100% by 1 week.12,13 The submu-
The second analyzes different technical options for creating
cosal layer is, in fact, where the tensile strength of the bowel
anastomoses. The third and final section concentrates on the
operative techniques that are currently used in constructing lies, as a consequence of its high content of collagen fibers
intestinal anastomoses. [see Figure 1]. Therefore, in constructing a hand-sewn intes-
tinal anastomosis, it is imperative that this layer is included
when extramucosal bites are taken. Collagen synthetic capac-
Intestinal Healing ity is relatively uniform throughout the large bowel but less
The process of intestinal anastomotic healing mimics that so in the small intestine: synthesis is significantly higher in the
of wound healing elsewhere in the body in that it can be proximal and distal small intestine than in the midjejunum.
arbitrarily divided into an acute inflammatory (lag) phase, a Overall collagen synthetic capacity is somewhat less in the
proliferative phase, and, finally, a remodeling or maturation small intestine. Although no significant difference has been
phase. Collagen is the single most important molecule for found between the strength of ileal anastomoses and that of
determining intestinal wall strength, which makes its metabo- colonic anastomoses at 4 days, colonic collagen formation is
lism of particular interest for understanding anastomotic much greater in the first 48 hours.14 It is noteworthy that the
healing. During the proliferative stage, fibroblasts become the synthetic response is not restricted to the anastomotic site but
predominant cell type, playing an important role in laying appears to be generalized to a significant extent.15 The pres-
down collagen in the extracellular space. At the epithelial ence of the visceral peritoneum on the bowel wall also has an
level, the crypts undergo division to cover the defect on the influence on the ease with which two bowel ends can be
luminal surface of the bowel. The density of collagen synthe- joined. This effect is highlighted by the increased technical
sis is in a constant state of dynamic equilibrium, which is difficulty of joining extraperitoneal bowel ends, for example
dependent on the balance between the rate of synthesis and the thoracic esophagus and the rectum.
DOI 10.2310/7800.S05C29
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5 GASTROINTESTINAL TRACT AND ABDOMEN 29 INTESTINAL ANASTOMOSIS — 2
Table 1 Principles of Successful Intestinal Anastomosis
critical stage in collagen formation is the hydroxylation of
proline to produce hydroxyproline; this process is believed
Well-nourished patient with no systemic illness to be important for maintaining the three-dimensional triple-
No fecal contamination, either within gut or in surrounding helix conformation of mature collagen, which gives the mole-
peritoneal cavity
Adequate exposure and access
cule its structural strength. The amount of collagen found in
Well-vascularized tissues a tissue is indirectly determined by measuring the amount of
Absence of tension at anastomosis hydroxyproline, though no significant statistical correlation
Meticulous technique between hydroxyproline content and objective measurements
of anastomotic strength has ever been demonstrated.19 Vita-
min C deficiency results in impaired hydroxylation of proline
and the accumulation of proline-rich, hydroxyproline-poor
systemic factors
molecules in intracellular vacuoles.
Dehiscence has been linked adversely with increasing In high doses, corticosteroids have been associated with
age.16,17 This connection may be secondary to a number poor healing. One study employing therapeutic doses, how-
of factors, including the presence of comorbid conditions, ever, reported no difference in leakage rates was found
malnutrition, and vitamin deficiency. A study employing an between control subjects and those treated with steroids.17
in vivo model of severe protein malnutrition, which can occur
in advanced cancer, demonstrated a reduction in tissue local factors
collagen, as well as in the bursting pressure of colonic anas- Blood flow is a critical factor in tissue healing. The increased
tomoses.18 However, the introduction of parenteral nutrition vascularity of the bowel wall is the reason why gastric and
has not been shown to enhance anastomotic healing.18 small bowel anastomoses heal more rapidly than anastomoses
Several factors that are known to inhibit collagen synthesis, involving the esophagus or the large bowel. In preparing
such as vitamin C deficiency, zinc deficiency, jaundice, the bowel ends for anastomosis, it is imperative that the
and uremia, have a detrimental effect on tissue healing.16 A mesentery be prepared carefully and not dissected too far
Figure 1 Shown are the tissue layers of the jejunum. Most of the bowel wall’s strength is provided by the submucosa.
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5 GASTROINTESTINAL TRACT AND ABDOMEN 29 INTESTINAL ANASTOMOSIS — 3
from the bowel edge. Mesenteric compromise, secondary to a
overly enthusiastic dissection or inappropriate suturing, may
result in a reduction of perianastomotic blood flow. The
avoidance of tension at the anastomosis is also critical; this is
achieved through the appropriate mobilization of the splenic
flexure. Other factors that influence blood flow at the site of
anastomoses are hypovolemia and the viscosity of the blood.20
Radiation may damage the microcirculation and thereby
predispose to poor healing.17
Technical Options for Fashioning Anastomoses
Over the past 160 years, numerous different materials b
have been used to join one bowel end to another, including
substances such as catgut and stainless steel. Newer materials
include monofilaments and absorbable sutures. In the past
30 years, stapling devices have been embraced enthusiasti-
cally by the surgical community. The main attraction of
these devices lies in their ability to create a robust anastomo-
sis in a relatively short space of time. Their main drawback,
as with any technologically advanced device, is their cost.
More important, there continues to be some controversy
regarding which of the two methods of creating an anastomo-
sis yields better clinical outcomes.21 Accordingly, the follow- c
ing sections review the relative merits of hand-sewn and
stapled anastomoses.
suturing: technical issues
Choice of Suture Material
Apart from inert substances, most foreign materials will
evoke an inflammatory reaction in the human body. Surgical
sutures are no exception. Studies that have examined the
relative abilities of different suture materials to elicit such a
reaction have found that silk has a potent ability to cause a
cellular infiltrate at the site of the anastomosis that may per- Figure 2 Shown are stitches commonly used in fashioning
sist as long as 6 weeks after implantation.22 Substances such intestinal anastomoses: (a) the continuous over-and-over
as polypropylene (Prolene), catgut, and polyglycolic acid suture, (b) the interrupted Lembert suture, and (c) the
(Dexon) evoked a milder response.22,23 There is little differ- Connell suture.
ence between absorbable and nonabsorbable sutures with
respect to the strength of the anastomosis.
The ideal suture material is one that elicits little or no continuous single-layer technique for intestinal anastomosis
inflammation while maintaining the strength of the anasto- (in the small bowel and colon) with the two-layer interrupted
mosis during the lag phase of healing. This ideal substance technique. No significant difference was seen in the leakage
has yet to be discovered, but the newer generation of sutures, rate (3.1% for the single-layer technique versus 1.5% for the
which include monofilament sutures and coated braided two-layer). The added advantages of reduced operating times
sutures, represent a substantial advance beyond silk and other and cost were observed. In a case series review that included
multifilament materials. 3,027 patients who had single-layer anastomoses done with
continuous sutures, fistula rates ranged from 0 to 6.8%
Continuous versus Interrupted Sutures (mean fistula rate, 1.7%), which demonstrated that this
Both continuous and interrupted sutures are commonly suture technique could be safely performed.29
used in fashioning intestinal anastomoses [see Figure 2]. Ret-
rospective reviews have not shown interrupted sutures to Single-Layer versus Double-Layer Anastomoses
have any advantage over continuous sutures in a single-layer The technique of double-layer anastomosis, originating
anastomosis.24–26 Oxygen tension and blood flow, as discussed from work done by Travers and Lembert,29 has been
previously, are critical factors in anastomotic healing. Animal used traditionally for more than 100 years. A double-layer
studies indicated that perianastomotic tissue oxygen tension anastomosis consists of an inner layer of continuous or inter-
was significantly lower with continuous sutures than with rupted absorbable suture and outer layer of interrupted
interrupted sutures.27 This finding was correlated with absorbable or nonabsorbable suture [see Figure 3]. The tech-
an increased anastomotic complication rate and impaired nique of single-layer anastomosis was championed because of
collagen synthesis and healing with continuous sutures in a potential advantages such as reduced operating time and
rat model.28 A prospective, randomized trial compared the lower cost. The main issue to consider, however, is safety. A
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5 GASTROINTESTINAL TRACT AND ABDOMEN 29 INTESTINAL ANASTOMOSIS — 4
a b surgical practice dramatically. With modern devices, techni-
cal failures are rare, the staple lines are of more consistent
quality, and anastomoses in difficult locations are easier to
construct.
Three different types of stapler are commonly used for
fashioning intestinal anastomoses. The transverse anastomo-
sis (TA) stapler is the simplest of these. This device places
two staggered rows of B-shaped staples across the bowel but
does not cut it: the bowel must then be divided in a separate
step. The gastrointestinal anastomosis (GIA) stapler places
two double staggered rows of staples and simultaneously cuts
between the double rows. The circular, or end-to-end anas-
tomosis (EEA), stapler places a double row of staples in a
circle and then cuts out the tissue within the circle of staples
with a built-in cylindrical knife. All of these staplers are avail-
able in a range of lengths or diameters. Staplers may be used
to create functional or true anatomic end-to-end anastomoses
as well as side-to-side anastomoses. The original staplers
c d were all designed for use in open procedures, but there
are now a number of instruments (mostly of the GIA type)
available for use in laparoscopic procedures. The staples
themselves are all made of titanium, which causes little tissue
reaction. They are not magnetic and do not cause subsequent
difficulties with magnetic resonance imaging (MRI).
In a functional end-to-end anastomosis, two cut ends of
bowel (either open or stapled closed) are placed side by side
with their blind ends beside each other. If the bowel ends are
closed, an enterotomy must be made in each loop of bowel
to allow insertion of the stapler. A cutting linear (i.e., GIA)
stapler is then used to fuse the two bowel walls into a single
septum with two double staggered rows of staples and to
create a lumen between the two bowel segments by dividing
Figure 3 Double-layer end-to-end anastomosis.
(a) Interrupted Lembert stitches are used to form the
this septum between the rows. A noncutting linear (i.e., TA)
posterior outer layer. (b) A full-thickness continuous stapler is then used to close the defect at the apex of the
over-and-over stitch is used to form the posterior inner layer. anastomosis where the GIA stapler was inserted. An alterna-
(c) A Connell stitch is used to form the anterior inner layer. tive, and cheaper, method of closing the defect is to use a
(d) Interrupted Lembert stitches are used to form the anterior continuous suture. The cut and stapled edges of the bowel
outer layer. should be inspected for adequacy of hemostasis before the
apex is closed. Some authors suggest cauterizing these edges
to ensure hemostasis31; however, given that electrical current
randomized trial comparing the single- and double-layer
may be conducted along the metallic staple line to the rest of
techniques of anastomosis found no evidence that there was
the bowel, it is probably easier and safer simply to underpin
an increased risk of leak with the single-layer approach.29
bleeding vessels with a fine absorbable suture. It is also
However, the study groups (65 and 67 patients) were too
important to offset the two inverted staple lines before closing
small for any significant difference to be detected; the authors
stated that a multicenter trial comprising at least 1,500 the apex.32
patients would be required to establish whether any such True anatomic end-to-end stapled anastomoses may be
difference existed. Furthermore, a 2006 meta-analysis that fashioned with a linear stapler by triangulating the two cut
addressed this issue by analyzing six trials with data from ends and then firing the stapler three times in intersecting
670 patients (299 in the single-layer group, 371 in the double- vectors to achieve complete closure [see Figure 4]. The poten-
layer group) concluded that there was no evidence that tial drawback of this approach is that the staple lines are all
two-layer anastomoses yielded a lower rate of postoperative everted. It is often easier to join two cut ends of bowel with
leakage than single-layer anastomoses.30 an EEA stapler, which creates a directly apposed, inverted,
stapled end-to-end anastomosis. However, circular staplers
stapling: technical issues can be more difficult to use at times because of the need
to invert a complete circle of full-thickness bowel wall.
Choice of Stapler In addition—at least at locations other than the anus—they
Surgical stapling devices were first introduced by Hültl in typically require closure of an adjacent enterotomy.
1908; however, they did not gain popularity at that time and
for some time afterward because the early instruments were Staple Height
cumbersome and unreliable. The development of reliable, TA and GIA staplers are available with a variety of inserts
disposable instruments over the past 30 years has changed containing several different types of staples. These inserts
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a b
c d
Figure 4 (a) The bowel ends are triangulated with three traction sutures. (b) A noncutting linear stapler (TA) is placed between
two of the sutures. (c) The stapler is closed and the excess tissue excised. (d) The bowel is rotated, and steps b and c are repeated
twice more to close the remaining two sides of the triangle.
vary with respect to width, the height (or depth) of the closed healing site was provided by stapled anastomoses in which
staple, and the distance between the staples in the rows. They the staple height was adjusted to the thickness of the bowel
are designed for use in specific tissues, and it is important to wall.33 The next best blood flow was provided by double-layer
choose the correct stapler insert for a given application. In stapled and sutured anastomoses, followed by double-layer
particular, inserts designed for closing blood vessels should sutured anastomoses and tightly stapled anastomoses, in that
not be used on the bowel, and vice versa. With TA and EEA order.
staplers, it is possible to vary the depth of the closed staples
by altering the distance between the staples and the anvil as Single-Stapled versus Double-Stapled Anastomoses
the instrument is closed. The safe range of closure is usually To accomplish many of these anastomoses, intersecting
indicated by a colored or shaded area on the shaft of the staple lines are created. Initially, some concern was expressed
instrument. Thus, if full closure would cause excessive crush- about the security of these areas and about the ability of
ing of the intervening tissues, the stapler need not be closed the blade in the cutting staplers to divide a double staggered
to its maximum extent. A 1987 comparison of anastomotic row of staples. Animal studies, however, demonstrated that
techniques that used blood flow to the divided tissues as a even though nearly all (> 90%) of the staple lines that were
measure of outcome found that the best blood flow to the subsequently transected by a second staple line contained
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bent or cut staples, the integrity of the anastomosis was not unusual techniques
compromised in any way, nor was healing adversely In 1892, Murphy introduced his button, which consisted
affected.34,35 of a two-part metal stud that was designed to hold the bowel
hand-sewn versus stapled anastomoses edges in apposition without suturing until adhesion had
occurred.43 Thereafter, the stud was voided via the rectum.
Titanium staples are ideal for tissue apposition at anasto- Several modifications of this technique have been described
motic sites because they provoke only a minimal inflammatory since then, primarily focusing on the composition of the
response and provide immediate strength to the cut surfaces rings or stents. In particular, dissolvable polyglycolic acid sys-
during the weakest phase of healing. Initially, tissue eversion tems have been developed. These so-called biofragmentable
at the stapled anastomosis was a major concern, given that anastomotic rings leave a gap of 1.5, 2.0, or 2.5 mm between
everted handsewn anastomoses had previously been shown to the bowel ends to prevent ischemia of the anastomotic line.
be inferior to inverted ones; however, the greater support and The use of adhesive agents such as methyl-2-cyanoacrylate
improved blood supply to the healing tissues associated with to approximate the divided ends of intestinal segments has
stapling tend to counteract the negative effects of eversion. been studied as well.44 There was only a moderate inflamma-
In fact, one study found that bursting strength for canine tory response at the wound, which persisted for 2 to 3 weeks.
colonic end-to-end anastomoses was six times greater when Leakage rates were high, however, and many technical prob-
the procedure was performed with an EEA stapler than when lems remained (e.g., how to stabilize the bowel edges while
it was done with interrupted Dacron sutures.36 they underwent adhesion). Fibrin glues have also been
In 1993, a randomized multicenter trial studied 440 employed in this setting. Although these substances are not
patients who had either hand-sewn or stapled anastomoses strong enough to hold two pieces of bowel in apposition, they
after ileocolic resection for cancer.37 The patients were have been used to coat a sutured bowel anastomosis in an
assessed both clinically and by imaging for the presence of a effort to reduce the risk of anastomotic failure. To date, no
leak (consisting of a contrast enema at about 10 days after the controlled clinical trials have confirmed that this approach is
operation). The overall leakage rate in the hand-sewn group worthwhile.
was 8.3%, which compared unfavorably with the 2.8% rate
in the stapled group. A possible explanation for the higher factors contributing to failure of anastomoses
rate in the hand-sewn group might have been surgical
Type and Location of Anastomosis
inexperience with the variety of suture techniques used in the
study (end-to-end and end-to-side with either continuous or Since the introduction of stapling, there has been an
interrupted sutures). In a study from the West of Scotland increase in the number of extremely low anterior resections
and Highland Anastomosis Study Group that included data being performed routinely. The literature seems to suggest
on 732 patients at 5 centers, the rate of radiologically proven that rectal anastomoses are more prone to leakage than more
leakage was significantly higher in the sutured group (14.4% proximal joins are.7–9 A retrospective review of risk factors
versus 5.2%); however, no difference was seen with respect in patients undergoing rectal resection for cancer found that
to clinical leaks, morbidity, or postoperative mortality.38 A low anastomoses, defined as being 5 cm or less from the
1998 meta-analysis comparing the hand-sewn and stapled anal verge, were associated with a 6.5-fold increased risk of
techniques of intestinal anastomosis addressed 13 trials leakage when compared to anastomoses that were more than
published from 1980 to 1995.39 For colorectal anastomoses, 5 cm from the anal verge.45 Another study showed that the
no significant differences were seen in mortality, total leakage leakage rate was increased in patients undergoing low colorec-
rate, clinical leakage rate, radiologic leakage rate, tumor tal anterior resection in the absence of a proximal stoma (the
recurrence rate, or incidence of wound sepsis. Strictures leakage rate was 17%, which fell to 6% when a stoma was
and technical problems, however, were more common in the present).46 The technique of total mesorectal excision (TME),
stapled group. A subsequent meta-analysis that reviewed data which is now standard for rectal cancer operations, has
from 955 patients with ileocolic anastomoses reported reduced the local recurrence rate to 5% at 5 years.47 How-
a significant reduction in the overall leakage rate and the ever, the incidence of anastomotic leakage in patients under-
clinical leakage rate when stapling was employed.40 going TME for low anterior resection is higher in the absence
Even when the anastomosis had to heal under adverse of a defunctioning stoma (25% versus 8%).48 The Rectal
conditions (e.g., carcinomatosis, malnutrition, previous che- Cancer Trial on Defunctioning Stoma (a randomized multi-
motherapy or radiation therapy, bowel obstruction, anemia, center trial) studied the outcomes of 234 patients undergoing
or leukopenia), no significant differences have been demon- low anterior resection with a defunctioning stoma.4 The
strated between stapled and hand-sewn anastomoses. overall leakage rate was 19.2%; however, the rate in the group
Stapling has, however, been shown to shorten operating time, that had a stoma was only 10.3%, compared with 28.0% in
especially for low pelvic anastomoses. Cancer recurrence the group that did not. Therefore, it is safe practice to cover
rates at the site of the anastomosis have been reported to be a low anterior resection with a defunctioning stoma.
higher or lower depending on the technique used. Certainly,
suture materials engender a more pronounced cellular Patient Preparation
proliferative response than titanium staples do, particularly Patients who present in the emergency setting are usually
with full-thickness sutures as opposed to seromuscular ones, compromised in terms of hydration status, typically as a con-
and malignant cells have been shown to adhere to suture sequence of sepsis, obstruction, or a combination of the two.
materials.41,42 Preoperative fluid optimization is always necessary and may
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require the aid of intensivists. Before an elective procedure, suggest that there is an increased risk of Clostridium difficile–
the patient is assessed with regard to systemic diseases associated diarrhea with the use of cephalosporin, penicillin,
(e.g., cardiovascular, respiratory, or diabetes), and anemia is and clindamycin.60–62 Prophylaxis of thromboembolism [see
corrected. Adequate preoperative antibiotic prophylaxis has 6:6 Venous Thromboembolism] is mandatory in all patients
been shown to reduce the risk of postoperative infection in all scheduled to undergo intestinal anastomosis. There is very
types of bowel surgery and must be given at the start of the little evidence in the literature to indicate that thromboembo-
operation [see 1:1 Prevention of Postoperative Infection]. Some lism has any direct effect on anastomotic leakage rates.
patients require additional steroids perioperatively [see 8:10 However, mesenteric venous thrombosis (MVT) accounts for
Endocrine Problems]. one-tenth of acute mesenteric ischemic events.63 The extent
Mechanical bowel preparation (MBP) has been thought to of thromboses is variable, with the worst outcome being mes-
be an essential component of colorectal surgery for more than enteric infarction necessitating urgent repeat laparotomy.
100 years.49,50 Emptying the bowel before elective operations Inadequate prophylaxis may increase the risk that MVT will
on the colon was traditional until about 5 years ago, and occur postoperatively, especially in patients with other risk
indeed, this practice was recommended by the Association of factors (e.g., a hypercoagulable state, previous thrombosis, or
Surgeons of Great Britain and Ireland (ASGBI) until rela- a history of smoking).
tively recently.51,52 The evidence for MBP was derived from
Associated Diseases and Systemic Factors
observational studies showing that mechanical clearance of
feces from the bowel was associated with reduced morbidity Anemia, diabetes mellitus, previous irradiation or chemo-
and mortality in colonic surgery.53 Proponents of MBP listed therapy, malnutrition with hypoalbuminemia, and vitamin
several advantages, such as reduction in intraluminal bacte- deficiencies are all associated with poor anastomotic healing.
rial load, prevention of potential anastomotic disruption by Some of these factors can be corrected preoperatively.
fecal pellets and also easier handling of bowel.54 In recent Malnourished patients benefit from nutritional support deliv-
years, however, there has been a shift in practice regarding ered enterally or parenterally before and after operation [see
the use of MBP. 8:22 Nutritional Support]. Well-nourished patients appear not
A Swiss randomized clinical trial published in 2005 studied to derive similar benefits from such support.64
the effect of MBP on patients undergoing left-side colorectal Resections for Crohn disease appear to carry a significant
resection with primary anastomosis.54 The anastomotic leak- risk of anastomotic dehiscence (12% in one prospective
age rate proved to be lower in the group that did not receive study) even when macroscopically normal margins are
MBP than in the group that did. Furthermore, the former obtained.65 With the lifetime risk of repeated resections, stric-
group spent less time in hospital and exhibited less extra- tureplasty has therefore become an attractive alternative
abdominal morbidity (e.g., pneumonia and cardiac-related to resectional management of Crohn disease even in the pre-
problems). These results seemed to agree with the findings of sence of moderately long strictures, diseased tissue, or sites of
a Cochrane review.52 Two large randomized trials published previous anastomoses. This approach allows preservation of
in 2007 compared the outcomes of patients who underwent more of the length of the small intestine.
MBP (with either polyethylene glycol or sodium phosphate) The glucocorticoid response to injury may attenuate
and patients who did not.55,56 One recruited 1,431 patients physiologic responses to other mediators whose combined
undergoing elective colorectal surgery from 13 centers.55 effects could be deleterious to the organism.66 In animal
Leakage was defined by the onset of significant symptoms experiments, wound healing, as measured by the bursting
and corroborated by means of imaging. The rate of leakage pressure of an ileal anastomosis 1 week after operation, was
optimal at a plasma corticosterone level that maintained
was 4.8% in the MBP group, which was not significantly dif-
maximal nitrogen balance and corresponded to the mean
ferent from the 5.4% rate in the non-MBP group. The other
corticosterone level of normal animals.67 Both supranormal
trial examined 1,343 patients from 21 centers and found no
and subnormal cortisol levels resulted in significantly impaired
significant differences in outcomes (such as cardiovascular
wound healing, probably through different mechanisms. It
problems, general infections and surgical site infections)
is believed that slow protein turnover is responsible for
between the MBP group and the non-MBP group.56 How-
delayed anastomotic healing in adrenalectomized animals,
ever, in a a subsequent meta-analysis57 that examined data
whereas negative nitrogen metabolic balance is responsible
from 10 randomized trials conducted over the past 24 years,
for increased protein breakdown and delayed healing in
the rates of both anastomotic leakage and wound infection
animals with excess glucocorticoid activity.67,68
were significantly higher in the MBP group than in the
Lifestyle factors have also been associated with an increased
non-MBP group (5.1 versus 2.6% and 8.2% versus 5.5%,
risk of leakage. A Danish prospective study of 333 consecu-
respectively).57 Possible explanations of these findings include
tive patients undergoing colorectal resection collected lifestyle
immune changes in the colonic mucosa that might impede
information by means of a questionnaire.69 The overall leak-
wound repair.57 In view of the currently available evidence,
age rate was 15.9% (53 out of 333). Smoking was found to
some surgical institutions, including our own, have chosen
be associated with an increased risk of anastomotic leakage
to adopt a policy of employing fluid restriction and enemas
(relative risk 3.18), as was alcohol consumption exceeding 35
rather than MBP before elective colorectal surgery.58
units a week (relative risk 7.18).
Enemas are given to patients undergoing anterior resec-
tions to ensure that fecal matter does not impede the use of controversial issues in intestinal anastomosis
stapling devices. It is advisable for patients to stop eating
solid food 24 hours before the operation. Many trials Inversion versus Eversion
have confirmed the benefits of giving IV antibiotics over the The question of the importance of inversion (as described
perioperative period.59 However, there is some evidence to by Lembert in the early 1800s) versus eversion of the
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anastomotic line has long been a controversial one. It has study of pelvic drainage after a rectal or anal anastomosis
been argued that the traditional inverting methods ignore showed that prophylactic drainage did not improve outcome
the basic principle of accurately opposing clean-cut tissues. In or reduce complications.81 Yet another study reported
the late 19th century, Halsted proposed an interrupted the severe inflammatory reaction caused by drains at
extramucosal technique, which has since been assessed in anastomoses.82
retrospective3 and prospective65 reviews and found to have a Despite these findings, many surgeons elect to place an
low leakage rate (1.3% to 6.0%) in a wide variety of circum- intra-abdominal drain in the pelvis after an anterior resection
stances. A 1969 study reported greater anastomotic strength, or a coloanal anastomosis because of the higher than
less luminal narrowing, and less edema and inflammation usual risk that a fluid collection will develop. Drainage is
with everted small intestinal anastomoses in dogs.70 Subse- rarely helpful, or indeed easy, after a gastric or small bowel
quent laboratory and clinical studies have not confirmed anastomosis. Drains are indicated, however, after emergency
these findings and, in fact, have often yielded quite the oppo- operations for peritonitis or trauma in which it was necessary
site results: lower bursting pressure, slower healing, and more to close or anastomose damaged or inflamed bowel.
severe inflammation have all been associated with an everted
suture line.71–73 A 1970 trial, however, conclusively demon-
Operative Techniques for Selected Anastomoses
strated the importance of inverting the cut edges of bowel
in colorectal surgery. In this study, the rate of fecal fistula The following section covers the essential preliminary steps
formation was far higher in the group that had everted suture before a bowel anastomosis and then describes three generic
anastomoses (43%) than in the group with inverted suture operations involving the small and large bowel. These proce-
anastomoses (8%).74 dures illustrate many of the general principles previously
discussed (see above).
Nasogastric Decompression
Routine nasogastric decompression in patients undergoing patient positioning and incision
a procedure involving an intestinal anastomosis remains con- Patients must be positioned on the operating table in a
troversial. In retrospective75 and prospective,76 randomized, manner that is appropriate for the planned operation. Most
controlled trials, routine use of a nasogastric tube conferred abdominal operations are performed through a midline inci-
no significant advantage in terms of reducing the risk of anas- sion of adequate length with the patient supine. For pelvic
tomotic leakage. In fact, there was a trend toward an increased procedures, the patient is placed in the lithotomy position to
incidence of respiratory tract infections after routine gastric allow access to the abdomen and the anus; care must be
decompression.77 Nonetheless, one study found that nearly taken to position the legs and feet in the stirrups correctly,
20% of patients required insertion of a gastric tube in the without excessive flexion or abduction and with sufficient
early postoperative period.76 If the choice is made not to place padding to prevent pressure ulceration, thrombosis, and
a nasogastric tube routinely, it is important to remain alert neurapraxia. For esophageal procedures, the patient is posi-
to the potential for gastric dilatation, which can develop tioned lying on the appropriate side, and the incision of
suddenly and without warning. choice is a lateral thoracotomy [see 4:7 Open Esophageal
Procedures]. Occasionally, the patient must be shifted to a
Abdominal Drains different position during the course of an operation. Gravity
Fecal contamination from bowel surgery is a dreaded com- can be useful for moving structures out of the way. Accord-
plication. Peritoneal drainage is of the subject of considerable ingly, it is often helpful to alter the axis of the operating table.
controversy, with two basic schools of thought dominating.78 For example, a 30° head-down or Trendelenburg position
The first school accepts the possibility that drains may help facilitates pelvic operations.
with diagnosis by serving as an early warning system for either
anastomotic leakage or bleeding and makes the point that exposure, mobilization, and dissection
evacuating blood and serous fluid will reduce the risk of Access is a critical determinant of the ease with which
abscesses. The other school is skeptical about the benefits, an operative procedure can be carried out. Accordingly, the
arguing that drains may irritate the peritoneum, thus increas- incision must be made in such a way as to allow adequate
ing the production of serous fluid, and may provide a route exposure of the operating field. The lateral aspects of the field
whereby microbes can enter the peritoneal cavity. In addi- can be controlled by using a suitable retractor, which can be
tion, there is a potential risk that the drain may physically attached to the operating table. This measure allows more
impede the movement of the omentum and adjacent organs efficient use of operating assistants and space. Often, the
and consequently may hinder the body’s innate ability to wall colorectal surgeon is faced with operating in confined spaces,
off any possible infection. Finally, it is thought that drains are such as the pelvis. Therefore, it is important to be able to
at high risk for blockage. compartmentalize the abdomen. This can be achieved in a
Even before World War I, the old dictum “when in doubt, number of ways. The small bowel can be extremely difficult
drain” was called into question by Yates, who wrote that the to handle and therefore is commonly packed away by placing
peritoneal cavity could not be effectively drained because of wet gauze. The next stage involves bringing the bowel to the
adhesions and rapid sealing of the drain tract.79 Six decades surface. In the absence of adhesions or tethering caused
later, one study showed a dramatic increase in the incidence by disease, the small bowel is usually sufficiently mobile
of anastomotic dehiscence (from 15% to 55%) after the to allow the relevant segment to be brought out of the
placement of perianastomotic drains in dogs.80 This increase abdomen. Doing so makes the operation easier and allows
was associated with a significant increase in mortality. A 1999 the remainder of the bowel to be kept warm and tension free
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inside the abdominal cavity. Sometimes, the transverse colon results in a hematoma within the leaves of the mesentery,
and the sigmoid colon are mobile enough to be brought to which can itself threaten the viability of the bowel. Generally,
the surface. More commonly, however, as with the other sec- the bleeding vessel can be secured with a fine stitch; some-
tions of the large bowel, the peritoneum must be divided times, however, a limited further bowel resection is the only
along the lateral border of the colon and the retroperitoneal safe course of action. Both of these problems can be avoided
structures reflected posteriorly. Tension is rarely a problem by using the ultrasonic scalpel or the bipolar coagulating
with small bowel anastomoses, but with colonic or esophageal electrocautery.
anastomoses, it is absolutely vital that the two ends of bowel
to be joined lie together easily. For a large bowel anastomosis, Division of Bowel
this means that the splenic flexure or the hepatic flexure—or, If staplers are not available, the bowel segment to be
sometimes, both—must be adequately mobilized. removed is isolated between noncrushing clamps placed
Classically, the tissues around the bowel are divided with a across the intestinal lumen some distance away from the
scissors, whereas the mesentery is divided between clamps resection margin so as to limit the amount of bowel contents
and tied with a suitable thread. Recognized tissue planes are that can escape into the wound. Crushing clamps are then
separated by means of blunt dissection with either the fingers placed on the specimen side of the diseased segment at the
or a swab. Minor bleeding points are occluded with a coagu- point of the resection, and the bowel is divided with a knife
lating electrocautery, though this approach is often relatively just proximal and distal to the clamps. Thus, the lumen of
ineffective on mesenteric or omental vessels. The disadvan- the diseased segment is never open within the abdominal
tages of this dissection technique are that oozing from raw wound. Even so, the contents of the bowel between the open
surfaces can be a nuisance and that the tissues beyond a ends and the non-crushing clamps can leak into the wound.
tie are often bulky and leave dead tissue within the body To minimize this problem, it is usual to isolate the working
that may act as a focus for infection and adhesions. Newer area with abdominal packs, which are sometimes soaked in
methods of dissection that make use of the ultrasonic scalpel an antiseptic (e.g., povidone-iodine).
or the bloodless bipolar electrocautery prevent these prob- One advantage of using staplers for an anastomosis is that
lems by coagulating a small section of tissue between the jaws in most instances, division of the bowel can be accomplished
of the instrument and simultaneously occluding all blood without opening the lumen. A linear cutting stapler (e.g.,
vessels up to a certain size within the tissues. Consequently, GIA) transects the bowel and seals the two cut ends simulta-
bleeding is reduced, fewer (or no) ties are needed, and only neously. Unfortunately, in the pelvis, it is usually necessary to
a small quantity of dead tissue results at each point. Becom- employ an angulated noncutting linear stapler (e.g., TA) so
ing skilled in the use of these instruments often takes a little as to obtain as much length as possible distal to the lesion.
time, but the time is well spent, in that it is now possible to The proximal rectum is then clamped with a crushing bowel
perform an intestinal resection without resort to a single tie. clamp, and a long knife is used to transect the rectum
above the staple line. Even so, there remains the potential for
bowel resection leakage of a small amount of fecal material, which must then
The precise techniques involved in resecting specific bowel be suctioned away.
segments will not be discussed in great detail here. (Colonic
simple bowel closure
resection, for example, is described elsewhere [see 5:34 Seg-
mental Colon Resection].) The following discussion outlines There are occasions where the bowel damage requires
only the general principles. simple repair rather than a formal resection, as in the case of
a perforated duodenal ulcer or an iatrogenic injury sustained
Preparation during adhesiolysis. Such holes may be closed in a number of
The segment of bowel to be removed must be isolated with ways. Most surgeons would use a double layer of absorbable
an adequate resection margin. To this end, all surrounding sutures. Special mention should be made of the technique of
adhesions are divided. Next, the mesentery is divided. The strictureplasty, which is employed for a number of benign
key consideration in this step is to preserve the blood supply small bowel strictures (especially those resulting from Crohn
to the two remaining ends of bowel while still achieving disease) as a means of avoiding small bowel resection and
adequate excision of the diseased bowel. This is more easily anastomoses. In this procedure, the bowel is opened longitu-
accomplished in the small bowel than in the large bowel, dinally and closed transversely with a single layer of 2-0 poly-
thanks to the ample blood supply of the former; even so, glycolic acid sutures in a Connell stitch. Excellent functional
transillumination of the mesentery and careful division of the results have been achieved with this technique despite its
vascular arcade are vital. In the colon, the surrounding fat reputation for fistula formation, which is associated with
and the appendices epiploicae should be cleared from the Crohn disease.
remaining bowel ends so that subsequent suture placement is
straightforward. single-layer sutured extramucosal side-to-side
Care should be taken to avoid two common problems. enteroenterostomy
First, ties placed close to the bowel can bunch tissues A side-to-side anastomosis [see Figure 5] may be performed
excessively and thereby cause angulation or distortion of the when no resection is done, as a bypass procedure (e.g.,
free edge of the intestine, which can make the anastomosis a gastroenterostomy); after a small bowel resection; when
difficult and threaten the blood supply. Second, because there is a discrepancy in the diameter of the two ends to
mesenteric vessels are usually tied very close to their ends, the be anastomosed (e.g., an ileocolic anastomosis after a right
arteries sometimes slip back beyond the ties. Such slippage hemicolectomy);or when the anatomy is such that the most
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tied together and may simply be cut off. The remainder of the
posterior wall is sewn away from the surgeon in the same
manner as the portion already sewn, and the corners are
approximated with the baseball stitch. The anterior wall
is then completed with this second suture, either with
the Connell stitch or with an over-and-over stitch with the
assistant inverting the edges before applying tension to the
previous stitch.
When the defect is completely closed, the two sutures are
tied across the anastomotic line. The stay sutures are removed,
and the anastomosis is carefully inspected. Often, there is no
mesenteric defect to close in a side-to-side anastomosis, but
if there is one, it should be approximated at this point with
continuous or interrupted absorbable sutures, with care taken
not to injure the vascular supply to the anastomosis.
Figure 5 Single-layer sutured extramucosal side-to-side double-layer sutured end-to-side
enteroenterostomy. A full-length suture is started in the back enterocolostomy
wall and run through the seromuscular and submucosal
layers in the direction of the surgeon; the corners of the In this procedure, the end of the ileum is joined to the side
enterotomy are approximated with a baseball stitch, and a of the transverse colon [see Figure 6]. The distal colon is
single Connell stitch is used to invert the anterior layer. A divided with a cutting stapler so that a blind end is left. Some
second suture is started at the same spot on the posterior wall surgeons underpin or bury this staple line, though this prac-
and run in the opposite direction, again through all layers tice is probably unnecessary. The proximal cut end of the
except the mucosa; the corners of the enterotomies are intestine is similarly closed either with staples after division
approximated with a baseball stitch, and the suture is
with a cutting linear stapler or with a crushing bowel clamp.
continued in either the Connell stitch or the over-and-over
This proximal end is brought into apposition with the side of
stitch to complete the anterior wall of the anastomosis.
the distal bowel segment at a point no farther than 2.5 to
5 cm from the blind end of the distal segment; this proximity
tension-free position for the anastomosis is with the two to the cut end is important for prevention of the blind loop
bowel segments parallel (as in a Finney strictureplasty). syndrome.
Two stay sutures of 3-0 polyglycolic acid are placed Stay sutures of 3-0 polyglycolic acid are placed between the
approximately 8 cm apart on the inner aspect of the antimes- serosa of the proximal limb, about 10 to 15 mm from the
enteric border. A 5 cm enterotomy is made on each loop clamp, and the serosa of the distal limb. Interrupted seromus-
with an electrocautery or a blade on the inner aspect of the cular sutures of 3-0 polyglycolic acid are then placed between
antimesenteric border. If an electrocautery is used, care must these stay sutures, spaced about three to six to the centimeter.
be taken not to injure the mucosa of the posterior wall during These stitches may be tied sequentially or snapped and tied
this maneuver; placement of a hemostat into the enterotomy once they are all in place. It is crucial not to apply excessive
to lift the anterior wall usually prevents this problem. tension, which could cut the seromuscular layer or render it
Hemostasis of the cut edges is ensured, and the remaining ischemic. Suction is then readied. The staple line or crushed
enteric contents are gently suctioned out. A swab soaked in tissue on the proximal limb is cut off with a coagulating
povidone-iodine may be used at this point to cleanse the electrocautery or a knife; this maneuver opens the lumen of
lumen of the bowel in the perianastomotic region. the proximal limb. All residual intestinal content is gently
A full-length seromuscular and submucosal stitch of 4-0 suctioned.
polyglycolic acid is placed and tied on the inside approxi- An enterotomy or colotomy is created on the distal
mately 5 to 10 mm from the far end of the enterotomies. limb opposite the open lumen of the proximal bowel. A full-
The stitch is not passed through the mucosa: to do so would thickness suture of 3-0 polyglycolic acid is inserted in the
add no strength to the anastomosis and would hinder epithe- posterior wall at a point close to the far end of the enterotomy
lialization by rendering the tissue ischemic. A hemostat is and run in an over-and-over stitch back toward the surgeon.
placed on the short end of the tied suture, and the assistant The corner is rounded with the baseball stitch, and when the
applies continuous gentle tension to the long end of the anterior wall is reached, the Connell stitch is used. A second
suture. An over-and-over stitch is started in the direction of full-length 3-0 suture is started at the same point on the
the surgeon; small bites are taken, and proper inversion of posterior wall as the first, and the short ends of the two
the suture line is ensured with each pass through tissue. When sutures are tied together and cut. This second suture is then
the proximal ends of the enterostomies are reached, this run away from the surgeon to complete the posterior wall,
so-called baseball stitch is continued almost completely and the anterior wall is completed with the Connell stitch.
around to the anterior wall of the anastomosis. A single The two sutures are then tied across the anastomotic line.
Connell stitch may be used to invert this anterior layer. A second series of interrupted seromuscular stitches is then
Another full-length seromuscular and submucosal suture placed anteriorly in the same fashion as the seromuscular
of 4-0 polyglycolic acid is then inserted and tied at the same stitches placed in the posterior wall. It is important not
location in the posterior wall as the first. If the two sutures to narrow either lumen excessively by imbricating too much
are placed close enough together, the short ends need not be of the bowel wall into this second layer. The lumen of the
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a b
c
Figure 6 Double-layer sutured end-to-side enterocolostomy. (a) The proximal bowel end is stapled, interrupted Lembert
stitches are used to form the posterior outer layer, and a colotomy is made. (b) Two continuous sutures are used to form the
inner layer of the anastomosis; the posterior portion is done with the over-and-over stitch, the anterior with the Connell stitch.
(c) Interrupted Lembert stitches are used to form the anterior outer layer.
anastomosis is palpated to confirm patency, and the mesen- lithotomy position with the head tilted down, and the small
teric defect is closed if possible with either continuous or bowel is packed away in the upper abdomen. This positioning
interrupted absorbable sutures. The integrity of the join gives the surgeon the best access to the pelvis. The splenic
can be tested by injecting 20 mL of saline into the lumen of flexure and all of the distal large bowel are fully mobilized
the bowel, which is then placed under gentle pressure by along with the rectum. The proximal resection margin is
simultaneously finger-clamping the bowel a couple of centi- determined and cleared of serosal fat, and the bowel is divided
meters distal to the anastomosis and a couple of centimeters either with a GIA stapler or between crushing bowel clamps.
proximally. An angled TA stapler is fired across the distal rectal resection
margin, and another bowel clamp is placed proximal to it.
double-stapled end-to-end coloanal anastomosis The rectum is divided with a long-handled knife, with care
Resection of the distal sigmoid colon and the rectum is a taken to avoid plunging the blade into the pelvic sidewall,
common procedure. In the past, it often resulted in a perma- which could cause significant neurovascular damage. The
nent colostomy because of the technical difficulties associated specimen is removed and the stapler withdrawn. Adequate
with a hand-sewn anastomosis deep in the pelvis. The devel- pelvic hemostasis is ensured.
opment of circular staplers reduced the technical difficulty of Once the surgeon is satisfied that the bowel is sufficiently
the operation and made possible anastomoses as far down as mobilized, a noncrushing bowel clamp is placed on the colon
the anus [see Figure 7]. 10 to 15 cm proximal to the margin, and the crushing clamp
Proper preparation of the patient and the bowel is essential is removed. At this stage, it is usual to create an 8 to 10 cm
before resection of the rectum. The patient is placed in the colonic J pouch; this measure typically yields a substantially
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improved functional outcome, especially in the early postop- crunching sound is heard. The anvil is then loosened the
erative period in older patients.83 A whip-stitch (or purse- appropriate amount, and the entire mechanism is withdrawn
string suture) of 2-0 polypropylene is placed around the through the anus. Finally, the proximal and distal rings of
colotomy, and the anvil from the appropriately sized curved tissue, which remain on the stapler, are carefully inspected to
EEA stapler is inserted into the open end and secured in confirm circumferential closure of the staple line.
place by tying the suture [see Figure 7].The proximal bowel The pelvis is then filled with body-temperature saline,
clamp is removed. The assistant—who may also, if desired, and a Toomey or bladder syringe is used to insufflate the
gently wash out the rectal stump with a dilute povidone- neorectum with air. The surgeon watches for bubbling in the
iodine solution—performs a digital rectal examination. pelvis as a sign of leakage from the anastomosis. If there is a
The stapler, with its trocar attachment in place, is then leak, additional soluble sutures must be placed to close the
inserted into the anus under the careful guidance of the sur- defect and another air test performed. A rectal tube may
geon. The pointed shaft is brought out through or adjacent then be inserted by the assistant or may be placed at the end
to the linear staple line, and the sharp point is removed. The of the procedure. When the anastomosis is very low or there
peg from the anvil in the proximal colon is snapped into the is some concern about healing, a drain may be placed in
protruding shaft of the stapler, and the two edges are slowly the pelvis behind the staple line; however, as noted [see
brought together. The colonic mesentery must not be twisted, Controversial Issues in Intestinal Anastomosis, above], this
and the ends must come together without any tension what- practice has not been shown to be beneficial and may in fact
soever. The stapler is fired. In some types of stapling guns, a impair healing.
a b c
d e
Figure 7 Double-stapled end-to-end coloanal anastomosis. (a) The C-EEA stapler comes with both a standard anvil (left) and a
trocar attachment (right). A more recent version of these staplers comes with a trocar in the body rather than in the head of the
device. (b) The rectal stump is closed with an angled linear noncutting stapler. A purse-string suture is placed around the coloto-
my, and the anvil of the stapler is placed in the open end and secured. (c) The stapler, with the sharp trocar attachment in place,
is inserted into the anus, and the trocar is made to pierce the rectal stump at or near the staple line, after which the trocar is
removed. (d) The anvil in the proximal colon is joined with the stapler in the rectal stump, and the two edges are slowly brought
together. (e) The stapler is fired and then gently withdrawn.
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As noted (see above), a 1998 meta-analysis by Macrae factors and take the measures necessary to prevent any harm
demonstrated an association between stapled anastomoses that may ensue if leakage results. This may mean giving the
and an increased incidence of colorectal anastomotic stric- patient a temporary stoma. Even if fecal diversion has been
tures, in comparison with hand-sewn anastomoses.39 The carried out, it is important to keep watching closely for any
cause of this association remains uncertain. Most of these signs of failure and to take prompt action if such signs
patients were asymptomatic and in those who required treat- appear.
ment, simple dilatation was sufficient to rectify the problem. Anastomotic failure rates have improved over the past
A 2007 Cochrane review did not find the risk of anastomotic two centuries, and postoperative morbidity and mortality
stricture to be increased in patients undergoing ileocolic have decreased accordingly. These beneficial developments
resection with a linear cutting stapler.40 can be attributed to a combination of factors, such as
better appreciation of the principles of healing, improved
anesthesia, appropriate antibiotic prophylaxis, and enhanced
Conclusion postoperative monitoring. Currently, with the emergence
Any anastomosis, no matter how technically sound on of laparoscopic colorectal surgery, it is essential that the
creation, may fail. The limiting factor may be the tissue or surgeon continues to practice the same principles of creating
the resulting inflammatory sequelae that follow closure of a join—good apposition of the edges, without tension
the abdominal wall. Therefore, as for ultralow anterior and with an optimal blood supply—just as for open colorectal
resections, it is important to recognize any potential risk surgery.
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Acknowledgment
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