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19
Mesenteric component of right colectomy
J. CALVIN COFFEY AND STEVEN D. WEXNER
The perpetual obstacle to human advancement
is custom
John Stuart Mill
AIM
To demonstrate the importance of peritoneal and mesenteric-
based activities in excision of the ascending colon.
INTRODUCTION
Even to the present terminology such as ileocolic resection,
right hemicolectomy and colectomy are used in reference to
removal of the right side of the colon [1–4]. More recently,
the terms complete mesocolic excision (CME) and total/
partial right mesocolic excision are being increasingly used
in place of conventional terminologies [5–22]. e emer-
gence of this terminology followed that of “total mesorectal
excision,” a term that has widely (though not universally)
substituted “anterior resection” or “proctosigmoidectomy.”
e term total mesorectal excision implies that the entire
mesorectum has been excised intact. Given that the rectum
cannot be retained in the absence of a mesorectum, removal
of the rectum can be considered as implicit. Similarly, it is
argued that removal of the right side of the colon should
be referred to “total” or “partial right mesocolectomy”
[1–3,6–9]. e prex “total” or “partial” describes the extent
of the mesenterectomy performed and is thus informative.
Omission of these leave the reader unclear as to the extent of
mesenterectomy (if any) conducted.
A question arises as to whether the term “complete
mesocolic excision” should be adopted over “total or partial
right mesocolectomy” [2]. One could argue that “complete”
is inaccurate as in order to conduct a CME, the entire right
mesocolon and some of the small intestinal mesentery
(which are continuous structures) would require removal
(Figure 19.1). While the terms partial or total right meso-
colectomy (RMC) may be marginally more accurate, they
also suffer from the fact that there is no anatomic bound-
ary demarcating the termination of the small intestinal
mesentery and the commencement of the right mesocolon
(Figure 19.1). More recently, the term modifi d CME may
prove more acceptable [2,3].
ere is no doubt that a more accurate nomenclature is
required for colonic and rectal surgery and that this should
in some manner incorporate the extent of mesenterectomy
performed. In the absence of consensus, and in the interest
of being as informative as possible, some support usage of the
terminology “right mesocolic excision” as it informs on the
extent of mesenterectomy performed and at least attempts a
specicity in respect of the region of the mesentery resected
[1–4,8]. In the following, right mesocolectomy is used in place
of CME, ileocolic excision, and right hemicolectomy [2].
ANATOMY
e anatomy of the mesentery on the right side has been
dealt with in detail in Chapter 2. A brief recap of the main
principles is appropriate here. In describing the anatomic
features of the mesentery on the right, it is reasonable to
commence with a description of the mesentery followed by
peritoneal reections and congenital adhesions. In this man-
ner, one builds a composite anatomic picture that in turn
helps rationalize the procedural steps required to detach
and disconnect the mesentery during right mesocolectomy.
Aim 277
Introduction 277
Anatomy 277
Open right mesocolectomy 278
Minimally invasive right mesocolectomy 284
Introduction 284
Medial-to-lateral mesenteric detachment 285
Lateral-to-medial mesenteric detachment 287
Special considerations 290
Future directions 291
Summary 291
References 291
278 Mesenteric component of right colectomy
e small bowel mesentery curves down onto the pos-
terior abdominal wall and extends laterally as the attached
right mesocolon. Toldt’s fascia separates the mesocolon from
the underlying retroperitoneum. As the terminal ileum has
a junction with the cecum at the ileocecal junction, a sub-
stantial mesenteric tissue mass occurs at the ileocecal junc-
tion. e mesoappendix arises from the undersurface of this
conuence. Depending whether this is short or narrow, the
appendix adopts a retrocecal or a pelvic position [1,4,23,24].
Where the small bowel mesentery curves downward at
the mesenteric base a peritoneal reection is apparent. is
commences at the fourth part of the duodenum and extends
obliquely across the posterior abdominal wall to reach the
ileocecal mesenteric region. Division of the reection (i.e.,
peritonotomy) exposes the mesofascial interface between
small bowel mesentery and underlying Toldt’s fascia. Here,
it can be arbitrarily called the ileocecal peritoneal reection.
e peritoneal reection at the small bowel mesenteric base
has yet to be formally named (despite it’s being an anatomic
constant). e ileocecal peritoneal reection extends around
the inferolateral aspect of the cecum and then proximally as
the right peritoneal reection. Importantly, it “closes o”
access to the colofascial and mesofascial interface in this
region [1,2,4,23,24].
e ileocecal peritoneal reection continues around
the hepatic exure as the peritoneal component of the lat-
ter, where it is called the hepatocolic reection. e greater
omentum coalesces to varying degrees with the superior
surface of the hepatocolic reection. Although the right
mesocolon is attached to the retroperitoneum, it is sepa-
rated from the latter by Toldt’s fascia. Beneath the fascia lie
retroperitoneal structures (i.e., ureters, gonadal vessels, and
duodenum) [1,2,4,23,24].
In describing the activities required for right mesocolec-
tomy, the terms mesofascial and colofascial separation
will be repeatedly used. Mesofascial separation is separa-
tion (or detachment) of mesentery from underlying fascia
and colofascial separation is separation of the colon from
underlying fascia. As mentioned previously, a plane is the
interface between two contiguous surfaces. In the case
of the mesofascial plane, the contiguous surfaces are the
mesocolon and fascia. In the case of the colofascial plane,
the contiguous surfaces are the colon and fascia. A further
terminology, retrofascial separation, refers to the separa-
tion of the fascia from the underlying retroperitoneum (an
approach adopted in some institutes) [1–4,23,24].
OPEN RIGHT MESOCOLECTOMY
e abdomen is opened via a midline laparotomy and
adequate access obtained using the principles described in
Chapter 16. In keeping with this, the greater omentum (if
attached) is separated from the right colon by division of
adhesions. It may also be necessary to separate the small
bowel and associated mesentery via adhesiolysis. In this
manner, the right colon, mesocolon, terminal ileum, and
ileocecal mesenteric conuence are fully exposed. Special
circumstances arise when the pathology encountered
impedes access to these structures and will be dealt with in
a later section of this chapter.
e lateral-to-medial approach is begun by liing the
right colon off the posterior abdominal wall, placing the right
peritoneal reection under tension. Congenital adhesions
may occur between the right colon and lateral abdominal
wall. ese initially obscure the right peritoneal reection
and must be divided (Figure 19.2). Aer their division,
the right colon is lied away from the posterior wall. is
exaggerates the grove formed by the right peritoneal reec-
tion. e groove at the reection is exaggerated, identifi d,
and divided through. Following peritonotomy, the plane
between the colon and underlying fascia can be identifi d
(the colofascial interface). If the plane is not readily appar-
ent, then the colon can be lied further away from the ret-
roperitoneum. e traction transmitted to the colofascial
interface is usually sucient to permit its identication and
detachment can be achieved [2].
When colofascial separation has been completed and
the colon detached, the mesofascial interface is seen
(Figure 19.2). Mesofascial separation involves liing the
colon upward and medially and concurrently displacing
the fascia toward the retroperitoneum. e right peritoneal
reection is divided further, enabling continued mesofas-
cial separation (Figure 19.3). e activities of peritonotomy
and mesofascial separation are continued until further mes-
enteric detachment is limited by the ileocecal and hepato-
colic exures.
At this point, the right colon is still attached at the ileoce-
cal junction and the hepatic exure. To mobilize the former,
the ileocecal peritoneal reflection is divided (Figure19.4).
e fascial interface between the ileocecal mesenteric
Mesenteric and mesocolic continuity
Right mesocolon
Small bowel
mesentery
Transverse
mesocolon
Figure 19.1 (See also QR 1 and 7.) Intraoperative image
demonstrating continuity between small intestinal mesen-
tery, right and transverse mesocolon.
Open right mesocolectomy 279
exure and underlying retroperitoneum is viewed and com-
ponents separated (Figure 19.4).
Next, the peritoneal reection at the base of the small
intestinal mesentery is sharply divided. e peritonotomy
is extended proximally to the fourth part of the duode-
num (Figure 19.5). e mesofascial interface between
small intestinal mesentery and fascia is identifi d and
components separated. At this point, the lateral, infe-
rior, and medial planes of dissection meet. e remain-
ing attachments are the mesenteric root region (where the
superior mesenteric vein courses toward and the superior
mesenteric artery emerges from the pancreas) and the
hepatic exure [2].
To mobilize (i.e., detach) the hepatic f lexure, peri-
tonotomy of the right peritoneal ref lection is extended
around the hepatocolic reflection (Figure 19.6). This
exposes the colo- and mesofascial interface so their com-
ponents can then be separated. The complex formed by
mesentery and intestine can now be medialized as far as
the third part of the duodenum and head of the pancreas
(Figure 19.6).
Not infrequently, the greater omentum coalesces with
the hepatocolic reection. In order to separate the greater
omentum, the omento-colic reection is divided at the mid-
transverse colon level (Figure 19.7a). is permits access to
the lesser sac and enables the surgeon separate the greater
omentum from the upper surface of the transverse meso-
colon. If this activity is continued from the midline toward
the hepatic exure, the hepatocolic peritoneal reection is
exposed.
At this point, the mesentery has been fully mobilized.
e remaining attachment is the mesenteric root region,
where the superior mesenteric artery comes through the
head of the pancreas (Figure 19.7b). If the mesentery has
been fully mobilized, then the head of the pancreas and
second part of the duodenum are clearly seen (Figure19.7b).
Once the mesentery has been mobilized the associated
bowel is by denition fully mobilized. A resection and
Right
(ascending)
colon
Congenital adhesions and right peritoneal re˜ection
Congenital
adhesions
(a)
(b)
Cecum
Right
peritoneal
reflection
Figure 19.2 (See also QR 2/3-5.) (a) Congenital adhesions between the right colon and lateral abdominal wall. These
obscure the right peritoneal reection from view. They become apparent after the ascending colon has been retracted
medially. They impede direct access to the right peritoneal reection unless divided. (b) Intraoperative appearance of
right peritoneal reection after division of congenital adhesions. The reection has been divided (i.e., peritonotomy) and
the surgeon has placed his ngers underneath the reection.
280 Mesenteric component of right colectomy
(b)
Exposed surface
of right mesocolon
Right mesocolic
(Toldt’s ) fascia
Divided edge
of right
peritoneal
reflection
Divided edge
of peritonotomy
Right
peritoneal
re˜ec tion
(a)
Right mesofacial plane and mesofacial separation
Figure 19.3 (a) (See also QR 6/3.) Right peritoneal reection after division. The ascending colon is retracted medially and
the peritoneal reection brought under stretch. This enables its division without entering underlying structures. (b) Right
mesofascial plane. Toldt’s fascia is interposed between the right mesocolon and retroperitoneum. The plane becomes
apparent after the right colon and mesocolon are lifted away from the posterior abdominal wall.
Open right mesocolectomy 281
Small
bowel
mesentery
Mesocolon
Mesofacial interface beneath ileocecal peritoneal reflection
Peritonotomy
margin
(a)
(b
)
Mesocolon/small
bowel mesentery
Peritonotomy
margin
Toldt’s
fascia
Pe
ritonotomy
margin
Figure 19.4 (See also QR 3d/3.) (a) Ileocecal peritoneal reection viewed from above and toward the midline. The reec-
tion has been grasped with a forceps and retracted toward the midline. (b) Mesofascial interface beneath the ileocecal
peritoneal reection. The interface is exposed following peritonotomy here. The interface is formed between Toldt’s
fascia and the conuence between small intestinal and right mesocolon. Toldt’s fascia overlies the retroperitoneum. If the
interface is not immediately apparent, then retraction of the mesentery to the right and away from the posterior abdomi-
nal wall will demonstrate it.
282 Mesenteric component of right colectomy
Peritoneal reflection at base of small intestinal mesentery
Small
intestinal
mesentery
Peritoneal
reflection
at base of
mesentery
Retroperitoneum
(a)
Small
intestinal
mesentery
Toldt’s
fascia
(b)
Figure 19.5 (See also QR 8/1.) (a) Peritoneal reection at base of the small intestinal mesentery. To generate this view, the
small bowel and mesentery are retracted to the right. This places the reection under stretch. The surgeon is pointing in
the direction of the mesenteric root region. (b) Mesofascial interface beneath the ileocecal peritoneal reection. The inter-
face is exposed following peritonotomy here. The interface is formed between Toldt’s fascia and the conuence between
small intestinal and right mesocolon. Toldt’s fascia overlies the retroperitoneum. In order to demonstrate the interface, the
small bowel mesentery is retracted away from the posterior abdominal wall and to the right. The peritoneal reection is
grasped and retracted to the left.
Open right mesocolectomy 283
Hepatocolic
peritoneal reflec
tion
Mesofacial
plane
Toldt’s
fascia
Transverse
mesocolon
Hepatocolic peritoneal reflection and mesofacial plane
(a)
(b)
Figure 19.6 (See also QR6/7 and 8.) (a) The hepatocolic peritoneal reection. This is demonstrated by retracting the colic
component of the hepatic exure toward the left iliac fossa. (b) The mesofascial interface after peritonotomy of the hepa-
tocolic peritoneal reection. Once the reection has been divided, the fascia and the interface are apparent with contin-
ued downward retraction of the colon.
284 Mesenteric component of right colectomy
mesenterectomy can then be conducted. Intestinal division
is completed using cutting or stapling techniques and is
followed by exposure of the intestinal margin of the mes-
entery. As described in previous chapters, the mesentery is
divided (and disconnected from adjacent structures) into
avascular interpedicular and adipovascular pedicle regions.
ese can be diffe entiated by backlighting the mesentery.
e means by which the mesentery is divided is predicated
on the thickness and consistency, but this can usually be
completed by developing a window in interpedicular areas,
cross- clamping pedicular regions, and dividing between
these. All mesenteric stumps are suture ligated in a hemo-
static manner.
e steps in anastomosis can be completed quickly by
attending to the details listed earlier. In contrast, the mes-
enteric mobilization and division take a signicantly longer
time to complete eff ctively and safely. In fact, most of the
time spent in operating is spent in detaching and discon-
necting the mesentery, and not the intestine.
MINIMALLY INVASIVE RIGHT
MESOCOLECTOMY
Introduction
As in open right mesocolic excision, the primary goals
are (a) mobilization (i.e., detachment) of the intestine and
mesentery back to the mesenteric root region and (b) dis-
connection of the mobilized intestine and mesentery.
When mobilization is complete, only the root region and
the middle colic adipovascular pedicle remain as points of
suspension. Mobilization can be conducted via medial-to-
lateral or lateral-to-medial approach. Most recommend that
the approach be tailored to the intraoperative ndings. e
medial-to-lateral approach requires that the adipovascular
pedicle be exposed and surgically divided in order to permit
access beneath the right mesocolon. e lateral-to-medial
approach does not require adipovascular pedicle ligation.
Once intestinal and mesenteric mobilization are completed,
Omentum
Divided edge
of omento-c
olic
reflection
Omento-colic
reflection
Transverse
colon
(a)
(b)
Mesenteric
root region
Duodenum
(second pa
rt)
Head of
pancreas
Omento-colic peritoneal reflection
Figure 19.7 (a) Intraoperative view of the peritoneal reection that connects the greater omentum to the underlying
transverse colon (i.e., the omento-colic reection). This must be divided through to expose omentocolic adhesions.
Division of these leads to complete mobilization of the transverse mesocolon and unimpeded access to the lesser sac.
(b)Intraoperative view of the second part of the duodenum and head of pancreas after detachment of the right mesoco-
lon and small intestinal mesentery. The mesentery remains attached only at the root region.
Minimally invasive right mesocolectomy 285
the right colon and mesocolon can be easily exteriorized
and all vascular pedicles directly ligated. e following will
address the ileocolic adipovascular pedicle and medial-to-
lateral mobilization rst. It is followed by a description of
the key steps involved in lateral-to-medial mobilization.
Medial-to-lateral mesenteric detachment
e patient is then placed in a gentle head down position with
the right shoulder raised. e small bowel will gravitate away
from the right mesocolon. Access to the latter is sometimes
impeded by the greater omentum that must be separated from
it. Adequate right mesocolic access is a requirement in laparo-
scopic right mesocolectomy. A further assistant port (5mm)
placed in the right iliac fossa is oen useful. e assistant
places a toothed grasping device through this port, grasps an
appendices epiploicae, and places it under tension toward the
right side. e eff ct is to transmit tension to the right meso-
colon (without tearing it), which in turn exaggerates the ileo-
colic adipovascular pedicle (Figures 19.8 and 19.9a).
e avascular interpedicular region on either side can
be quickly divided through until the mesofascial plane is
identifi d. e mesofascial plane is developed by inserting
an instrument into the window created, liing the right
mesocolon upward, and displacing the fascia posteriorly
(Figure 19.9b). Separation of Toldt’s fascia detaches the right
mesocolon (i.e., mesofascial separation). is is completed
as far laterally as possible aer which attention is turned to
the adipovascular pedicle (Figure 19.9b).
e adipovascular pedicle is skeletonized under high
magnication with a “chimney” for smoke evacuation. e
fat of the adipovascular pedicle is divided in a stepwise and
gradual manner using an harmonic scalpel. In this manner,
the fat on the anterior, anterolateral, and posterolateral aspect
is dealt with. However, mesenteric fat on the far side of the
pedicle cannot be directly cleared given the limitations of the
30° laparoscope lens. To overcome this, a curved retraction
device (see below) can be gently inserted to generate a mesen-
teric window on the opposite side of the pedicle (Figure 19.9c).
One such retractor has a retractable and blunt tipped blade
that is curved. is combination of features makes it suited
for gentle introduction immediately posterior to the vessel.
ere are numerous means by which ileocolic ves-
sels may be divided. One includes insertion of a stapling
device in the left upper quadrant port. Under direct view,
the stapling device is articulated to allow placement of the
narrow blade behind the vessel prior to closure. Ideally, one
should keep the jaws of the stapler closed for approximately
Ileocolic
adipovascular
pedicle
Ileocolic adipovascular pedicle—Medial view point
To right
mesocolon
(a)
(b)
To small
bowel
mesentery
Ileocolic
adipovascula
r
pedicle
To small
intestinal
mesentery
5
Figure 19.8 (See also QR 1/5.) Laparoscopic view of the ileocolic adipovascular pedicle. The cecum is retracted toward the
right and anterior abdominal wall. This lifts the pedicle away from the retroperitoneum and exaggerates the pedicle. (a)
Intraoperative view of the ileocolic adipovascular pedicle in a thin individual as seen during laparoscopic right mesocolec-
tomy (i.e., hemicolectomy). Continuity is apparent between the small intestinal mesentery on the near side of the mesen-
tery, and the right mesocolon on the far side. (b) Similar view of the ileocolic adipovascular pedicle as observed during
laparoscopic surgery in a patient with an elevated BMI.