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342 H. Kessler et al.
Fig. 36.5 The fusion planes of the peritoneum during development. The mesentery of the
transverse colon fuses with the greater omentum. There is a continuously running plane from the
pancreas across the duodenum towards the transverse mesocolon which can be identified during
surgery to ‘turn back’ embryology. The ligament of Treitz is shown here as a duplication of the
mesentery on the aorta. Reprinted with permission, Cleveland Clinic Center for Medical Art &
Photography ©2020. All Rights Reserved
to surgical resection, which is recommended for T3–T4 cancers, any lymph node
involvement, and in cases where the tumor is close to the mesorectal fascia.
The preoperative identification of vascular anatomical variations can be helpful
at the time of the surgery. The anatomy of the left sided colonic arteries is relatively
simple although variations can occur (Fig. 36.6). The left colic artery (LCA) is
absent in only 5% of individuals. The origin of the first sigmoid artery is variable,
as it arises from the inferior mesenteric artery (IMA) as a separate artery (Type 1) in
41–58% of individuals, from the LCA (Type 2) in 27 – 45%, and at the angle
between the LCA and IMA (Type 3) in 9–15%. The number of sigmoid arteries
varies usually between one and five, with two (21–40%), three (32–50%), and four
(7–25%) as the most common numbers.
The right side of the colon derives from the midgut and is supplied by the
superior mesenteric artery (SMA). The ileocolic artery (ICA) is consistent, and
supplies the cecum, ascending colon and, through anastomoses with the SMA, the
terminal ileum (Fig. 36.7a–c). The anatomy of the middle colic artery (MCA) and
the right colic artery (RCA) varies. The MCA has more than one separate branch
36 Mesenteric Considerations in Surgery of the Colon and Rectum 343
Fig. 36.6 Variations in anatomy of inferior mesenteric artery (IMA). In type 1, the first sigmoid
artery (SA) branch arises directly from the IMA. In type 2, the SA arises from the left colic artery
(LCA). In type 3, the SA and LCA arise together at an angle from the IMA. Reprinted with
permission, Cleveland Clinic Center for Medical Art & Photography ©2020. All Rights Reserved
arising directly from the SMA in 4–36% of cases. In a few cases a left branch of the
MCA might arise from the dorsal pancreatic artery or the IMA. The RCA is an
artery supplying the middle part of the ascending colon, arising from the SMA, and
running inferior to the avascular mesocolic window covering the duodenum.
However, the RCA is present as a separate artery in only 11–20% of cases.
Surgical Approach
The classic open approach utilizes a lateral-to-medial dissection for benign and
malignant disease, although a posterior and medial-to-lateral approach have also
been described. With the integration of minimally invasive surgery in colon and
rectal cancer, the development of the medial-to-lateral approach has become widely
adopted, but the lateral-to-medial approach is equally acceptable. There are a
variety of minimally invasive options for colon and rectal resections.
Laparoscopy enables an intracorporeal anastomosis while hand assisted surgery
344 H. Kessler et al.
Fig. 36.7 Variations of arterial supply to the right colon. a The ileocolic (ICA), the right colic
(RCA) and the middle colic (MCA) arteries originate independently from the superior mesenteric
artery (SMA). b The RCA originates from the ICA, and a common trunk of the MCA supplies the
hepatic flexure and the right two-thirds of the transverse colon. c The two main branches of the
MCA originate separately from the SMA, with the right branch of the MCA supplying the distal
part of the ascending colon and the hepatic flexure. Reprinted with permission, Cleveland Clinic
Center for Medical Art & Photography ©2020. All Rights Reserved
facilitates entrance of a hand into the dissection field to assist with retraction and
additionally provides a potential extraction site for assistance with the anastomosis.
In laparoscopic assisted surgery, the dissection is laparoscopically performed, while
the anastomosis is perfor med through a mini-laparotomy under direct visualization.
More recently, robotic assisted surgery is becoming integrated into colon and rectal
resections. The surgical approach should not alter the surgical goals, to obtain a
complete resection including a complete lymph node resection, negative circumferential margins, while preserving surrounding structures and preventing unnecessary complications. For simplicity, this chapter will focus on the description of
the open approach.
Surgical Management of Colon Cancer
Surgical principles of colon cancer resection are based upon lymph nodes in the
colonic mesentery and as described above, the technical details of lymph
node dissection within the specimen vary based upon location. It is globally
accepted that an incre ased number of lymph nodes improves survival, and the main
relevant vessels should be centrally ligated. The techniques currently practiced vary
36 Mesenteric Considerations in Surgery of the Colon and Rectum 345
from a traditional high ligation of the vessels and dissection of at least 12 lymph
nodes without specific considerations regarding the mesocolon, to CME and CVL
as refined techniques, and the D3 lymphadenectomy in mainly Japan. We describe
the CME and CVL technique in resection of colon cancer which focuses on sharp
separation of the colon and mesentery following the embryologic planes and
respects the completeness and quality of the preservation of surfaces of the
mesocolon.
Cecal and Ascending Colon Carcinoma
For right-sided cancer, or tumors located in the cecum and ascending colon below
the hepatic flexure, a right colectomy is the treatment of choice (Fig. 36.8). The
resection should include ligation at the origin of the ileocolic artery and right branch
of the middle colic artery, with lymph node removal along both vessels down to the
origin. If the right colic artery is present, the ligation should also be at the origin. To
enter the correct surgical plane between the retroperitoneal and visceral peritoneum,
retraction of the lateral peritoneal reflection allows for identification of the white
line of Toldt where parietal and visceral peritoneum are fused, and the initial entry
point should be away from the tumor to preserve the circumferential surgical
Fig. 36.8 Right
hemicolectomy. Reprinted
with permission, Cleveland
Clinic Center for Medical Art
& Photography ©2020. All
Rights Reserved
346 H. Kessler et al.
margins. With careful traction on the ascending colon using a gauze, the mesocolon
is sharply dissected from the parietal peritoneum of the retroperitoneum, with care
to preserve the mesocolon. This dissection continues to mobilize the entire right
colon from the lateral and posterior attachments following the embryologic planes
cephalad. Medially, areolar tissue is centrally encountered and the duodenum and
pancreatic head are sharply mobilized off of the mesocolon and remain in the
retroperitoneum. To completely expose the central nodes, a Kocher maneuver is
recommended. The anterior surface of the superior mesenteric vein (SMV) is a
landmark and is exposed and the superior mesenteric artery (SMA) remains to its
left and further posterior.
Mobilization in this area should be performed with caution due to numerous
anatomic variations of the veins forming the gastrocolic trunk of Henle (GTH) or
the “bleeding point” (Fig. 36.9a–e). Proximally the anterior and superior
Fig. 36.9 Gastrocolic trunk
of Henle (GTH). The venous
drainage around the hepatic
flexure is highly variable
and bears high risk of
bleeding during surgical
dissection. Henle’s trunk
depicts the point of drainage
of the superior right colic vein
(SRCV), right colic vein
(RCV), right gastroepicolic
vein (RGEV) and the anterior
and superior
pancreaticoduodenal vein as
they form a trunk to enter the
SMV near the head of the
pancreas, many variations are
possible. The middle colic
vein (MCV) can also be in
close proximity (a–d).
Reprinted with permission,
Cleveland Clinic Center for
Medical Art & Photography
©2020. All Rights Reserved
This intraoperative picture
shows the veins (arrow) and
depicts that with inappropriate
traction the veins can be at
risk of injury (e)
e
36 Mesenteric Considerations in Surgery of the Colon and Rectum 347
Fig. 36.10 CT scan of right
colon cancer with tumor
recurrence in
the central mesentery (white
arrow) in axial (a) and coronal
(b) views at root of
mesocolon likely from an
incomplete mesenteric
resection. The duodenum is
identified by a yellow arrow
showing the importance of
complete central resection to
prevent recurrence
pancreaticoduodenal veins, the right gastroepiploic vein, right colic vein, and
superior right colic vein form the trunk of Henle; however, many variations are
possible as also right colic vein and middle colic vein (MCV) may flow to the
GTH. Most frequently, the middle colic vein has a separate mouth towards the
SMV. Also, the SMV itself may be split up into two branches: a jejunal and an ileal
one. Any transection of the GTH demands clarity of the anatomic situation in order
to avoid complications. In order to prevent bleeding, traction of the mesocolon in
this area must be done carefully during the separation of the mesocolon from the
pancreas and the duodenum. At least the right colic and superior right colic veins
should be ligated to gain full access to the SMV.
After full access, the vessels are ligated; the ileocolic artery and vein should be
identified and individually secured. The ileocolic artery may pass posterior to the
SMV in 40% of patients, thus the origin of the ileocolic vessels should be identified
to verify ligation of the artery at its origin and to avoid injury to the jejunal trunk.
All lymph nodes should be dissected with the specimen in this area including those
overlying the SMV at the root of the right mesocolon (Fig. 36.10a, b). If the right
colic artery is present (11–20%) it should be taken with high ligation. The middle
348 H. Kessler et al.
colic artery is identified and lymph nodes over the base should be removed en bloc.
After the right branch of the middle colic artery is ligated at the branching of the
middle colic artery, the dissection should continue through the mesentery toward
the proximal transverse colon. Omental resection beyond 10 cm from the tumor is
not required; omentum within 10 cm from the tumor can be dissected from the
proximal transverse colon. After the transverse colon is divided between the right
and left branch of the middle colic artery, the ileum is divided 5–10 cm proximal
from the ileocolic valve. In this manner, the entire lymphatic field is resected after
which an ileocolic anastomosis is performed.
Hepatic Flexure Carcinoma
Additional lymph node clearance is required for cancers at the hepatic fl exure and
central transverse colon. Approximately 5% of lymph node metastases can be found
over the head of the pancreas or along the lower edge of the pancreas, and 5–8%
lymph nodes along the greater gastroepiploic arcade along the greater curvature of
the stomach if lymph node involvement is present. An extended right hemicolectomy is required (Fig. 36.11). During the required resection, the greater curvature
Fig. 36.11 Extended right
hemicolectomy. Reprinted
with permission, Cleveland
Clinic Center for Medical Art
& Photography ©2020. All
Rights Reserved
36 Mesenteric Considerations in Surgery of the Colon and Rectum 349
Fig. 36.12 Lymphatic drainage along the transverse colon which involves the gastroepiploic
arcade (a) and lymph nodes overlying the head and lower border of the pancreas (b). Reprinted
with permission, Cleveland Clinic Center for Medical Art & Photography ©2020. All Rights
Reserved
should be freed of lymph nodes along the right gastroepiploic vessels to retrieve all
possible lymph node metastases.
350 H. Kessler et al.
The initial dissection is similar to the right hemicolectomy above, initially
incising into the lateral peritoneal re flection and continuing with sharp dissection of
the ascending colon from the retroperitoneum, Kocher’s maneuver, and identification of the ileocolic vessels, SMV and gastrocolic trunk of Henle which is ligated
centrally. The dissection is then extended by entering the lesser sac. The right
gastroepiploic artery is freed from the greater curvature of the stomach removing
the nodes along the right gastroepiploic arcade (Fig. 36.12a, b). The right gastroepiploic artery is ligated just below the pylorus while preserving the gastroduodenal artery. The gastrocolic trunk of Henle is next ligated, again traction of the
mesocolon may tear veins in this region and should be performed with caution. The
ileocolic artery and vein are centrally ligated as described above. The middle colic
vein and artery can be approached by further proximal dissection along the SMV as
a landmark. The middle colic vein and artery are ligated near their respective
origins and transected. Following the transection of the ileum at about 5–10 cm
proximal to the ileocolic valve, the mesocolon is separated at the level of the ligated
vessels along the SMV while preserving autonomic nerves along the SMV and
SMA. The transverse mesocolon is then completely dissected from the lower
margin of the pancreas. Lymph node metastases may be present on the lower border
of the pancreas, therefore, these lymph nodes below the pancreatic edge should be
removed and included when performing central transverse mesocolic dissection;
these nodes should be left behind only for technical reasons if they are fixed or the
patient has a history of pancreatitis to avoid risk of severe postoperative pancreatic
complications. The colon is transected distally to the level of the left branch of the
middle colic artery but at least 10 cm from the tumor edge, and an ileocolic
anastomosis is created.
Transverse Colon Carcinoma
These tumors are treated by resecting at least the transverse colon, central ligation
of the middle colic artery, and resection of the neighboring lymphatic vessels. The
greater omentum with the gastrocolic ligament and the gastroepiploic arcade corresponding to the location of the tumor is resected again observing that a minimal
clearance of 10 cm needs to be kept. As an anastomosis of the ascending colon to
the descending colon is not recommended, the resection usually favors an extended
right or left hemicolectomy or a subtotal colectomy.
Splenic Flexure Carcinoma
Splenic flexure carcinoma is unique because of its borderline localization between
midgut and hindgut with bidirectional lymph node spread towards middle colic
vessels and inferior mesenteric artery. Thus, it can be treated by a left or right sided
approach, howe ver, in most cases, an extended left colectomy is preferred. In order
to avoid complications with a transverse-descending colonic anastomosis, another
36 Mesenteric Considerations in Surgery of the Colon and Rectum 351
option is subtotal colectomy with an ileosigmoid anastomosis. The targeted arteries
for resection are the middle colic and the left ascending colic artery along with the
accompanying pericolic and central lymph nodes. Lymph nodes along the greater
gastroepiploic arcade at the greater curvature of the stomach should be included as
well requiring mobilization of the gastroepiploic arcade off the greater curvature of
the stomach 10–15 cm opposite to the tumor site. This maneuver allows the
omentum to accompany the specimen. There are potential communicating arteries
along the inferior border of the pancreatic tail and splenic hilum, thus lymph nodes
in this region should be removed.
The dissection starts with the skeletonization of the stomach; the transverse
colon and gastroepiploic arcade are prepared and en-bloc resection of the gastrocolic ligament and the omentum is planned. Following full separation of the
transverse mesocolon, the lesser sac is fully exposed, and the lymph nodes along
the lower edge of the pancreatic corpus and tail are also dissected with central
transection of the transverse mesocolon at its root. The ascending colon is mobilized but the ileocolic vessels and lymphatic dissection off the SMV and right colic
vessels are not required. Central vascular ligation of the middle colic vessels is
crucial as it allows dissection of the central lymph nodes. Up to 4–6% of lymph
nodes at the root of the middle colic artery can be involved with carcinoma. Full
mobilization of the splenic flexure and the descending colon is performed along the
embryological planes. The descending colon is transected at least 10 cm distally to
the tumor and the lymph nodes around the IMA are removed. The left colic artery is
ligated at its origin along the IMA, and the IMV is ligated centrally at the lower
border of the pancreas. The complete mesocolon, transverse and adjacent colon,
omentum, and gastrocolic arcade are removed en-bl oc as specimen.
Descending Colon Carcinoma
Carcinomas in the descending colon require a left hemicolectomy (Fig. 36.13) with
high ligation of the inferior mesenteric artery. Lesions located 10 cm away from the
splenic flexure do not necessitate removal of omentum or skeletonization. However,
splenic flexure mobilization is crucial for a tension-free anastomosis. The lateral
peritoneal attachment is sharply divided and the left mesocolon is dissected off the
retroperitoneum. Fatty tissue around the kidney, left ureter and gonadal vessels
remains covered by the parietal fascia. The omentum is mobilized from the left
transverse colon and the lesser sac is fully exposed. Subsequently, both layers of the
mesocolon are divided at the lower border of the pancreas and the integrity of the
mesocolon should be strictly preserved. The peritoneum over the aorta is opened to
achieve central access to perform central lymph node dissection around the IMA
which is divided at about 1 cm distally to its origin at the aorta. Injury to the
autonomic nerves in this area should be avoided. The IMV is transected centrally at
the lower border of the pancreas facilitating a tension-free colorectal anastomosis.
The colon is transected proximally at least 10 cm proximally and distally to the