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35 Mesenteric Resection in Upper Abdominal Surgery 331
Contraindications
Contraindications to mesenteric resection relate to contraindications for small bowel
resection. Absolute contraindications include poor blood supply to the ends of the
bowel for the anastomosis or unclear bowel viability after attempted revascularization. Relative contraindications include peritoneal sepsis and hemodynamic
instability.
Description of Surgery
Small Bowel Resection with Adjacent Mesentery (Open Approach, Hand Sewn Anastomosis)
The abdomen is entered through a standard midline incision. The abdomen is
explored in all four quadrants, and lysis of adhesions is performed in the area of
pathology only. The margins of resection are determined. The mesentery is scored
using electrocautery at the planned margins. A surgeon must ensure that the
mesentery encompasses only the vessels and lymph nodes (for oncologic staging if
required) related to the section of bowel that is to be removed (Fig. 35.2). A window is then made in the mesentery next the bowel at the margins. This can be done
with a right angle. A GIA stapler is then passed through the windows on either side
of the bowel. A blue (3.8 mm) load is typically used to divide the bowel. The
mesentery is then divided using electrocautery, suture ligation, or a harmonic
scalpel along the score lines. Division of mesentery in patients with Crohn’s disease
can be difficult due to its thickening from chronic inflammation. Vessel sealing
devices may not adequately provide hemostasis; therefore, overlapping clamps with
suture ligations should be used (Fig. 35.3). For a handsewn anastomosis, a 3-0 silk
is then used in an interrupted fashion to close the posterior layer (Lembert stitch).
The staple line is excised. The inner layer is then closed starting in the middle using
a 3-0 absorbable, double arm suture. Each arm closes the posterior inner layer in a
continuous fashion. After the corner, a transition stitch is performed from suturing
inside to outside to allow closure of the anterior layer. The outer anterior layer is
closed with a Lembert stitch. The mesentery is closed with 3-0 interrupted or
continuous silk to prevent internal herniation. The patency of the anastomosis is
confirmed by manual exploration. The anastomosis and mesentery is observed for
hemostasis. The abdomen is closed in a standard fashion.
332 S. Gaines and J. C. Alverdy
Fig. 35.2 Margins of small
bowel resection with adjacent
mesentery and accompanying
vasculature
Fig. 35.3 Small bowel
resection with thickened
mesentery performed with
suture ligation
35 Mesenteric Resection in Upper Abdominal Surgery 333
Complications
Early complications include mesenteric hematoma and anastomotic bleeding. Late
complications include bowel ischemia, prolonged ileus, anastomotic leak,
mechanical obstruction, wound infections, and enterocutaneous fistula.
Summary
Margins of a small bowel resection and mesentery must encompass relevant vasculature and lymph nodes. Status of the mesentery dictates bowel viability. It is
critical to ensure mesenteric hemostasis.
Suggested Reading
1. Minter RM, Doherty GM, editors. Current procedures: surgery. New York, NY: McGraw-Hill.
2. Cameron JL, Cameron AM, editors. Current surgical therapy. Philadelphia, PA: Elsevier.
3. Mulholland MW, Lillemoe KD, Doherty GM, Maier RV, Simeone DM, Upchurch GR, editors.
Greenfield’s surgery. Philadelphia, PA: Lippincott Williams & Wilkins.
Mesenteric Considerations in Surgery of the Colon and Rectum
Hermann Kessler, Mariane G. M. Camargo, and Kristen T. Crowell
Introduction
The mesentery is contiguous along the intestines from the esophagus to the distal
rectum. It has a different shape along the GI tract and provides suspension of the
intestines and encases the feeding blood vessels and draining lymphatics. In this
chapter we will describe the anatomic and functional aspects of the mesentery
which are important in surgical decision making in malignant and benign colon and
rectal resections.
Mesenteric Role in Diseases of the Colon and Rectum
36
Malignancy
The mesorectal plane, or the “Holy Plane”, was first described by R. J. Heald in
1984 and defined as the optimal plane for rectal cancer resection. Sharp dissection
along embryologic planes that separate the visceral (mesorectal) fascia off of the
surrounding parietal peritoneum provides a resected specimen containing the rectum, lymph nodes, lymphatic vessels, and surrounding fat within the mesorectum
H. Kessler (&)
Digestive Disease and Surgery Institute, Department of Colorectal Surgery, Cleveland Clinic,
9500 Euclid Avenue, A30, Cleveland, OH 44195, USA
e-mail: kessleh@ccf.org
M. G. M. Camargo
Department of Gastroenterology and Nutrology, Service of Colorectal Surgery, Hospital das
Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
K. T. Crowell
Department of Surgery, Division of Colon and Rectal Surgery, Beth Israel Deaconess
Medical Center, Boston, MA, USA
© Springer Nature Switzerland AG 2021
E. D. Ehrenpreis et al. (eds.), The Mesenteric Organ in Health and Disease,
https://doi.org/10.1007/978-3-030-71963-0_36
335
336 H. Kessler et al.
en bloc. This technique revolutionized rectal cancer operations and began the
investigation into complete mesenteric resections.
Malignant lymphatic spread to mesenteric lymph nodes is an important mechanism for systemic spread. Lymph node drainage from colorectal adenocarcinoma
follows the supplying arteries. Therefore, in addition to adequate intestinal margins,
resection of the mesenteric lymph nodes en bloc with the tumor is a key factor in
principles of oncologic resections. Lymph node involvement in colorectal cancer is
a significant and even an independent prognostic indicator. When lymph nodes are
found to be positive, adjuvant treatment is recommended. An increased number of
resected lymph nodes more precisely defines pathologic staging and improves
survival. Guidelines recommend resection and pathologic evaluation of at least 12
lymph nodes in all colon and rectal cancer specimens.
In the 1990s W. Hohenberger transferred the principles of TME to the colon in
an attempt to improve colon cancer outcomes. He introduced central vascular
ligation (CVL) and dissection along embryologic planes with preservation of the
anterior and posterior peritoneum of the mesocolon and named the procedure
“Complete Mesocolic Excision” (CME). With this technique, outcomes in colon
cancer improved stepwise at his home institution, the University of Erlangen,
Germany. The 5-year local recurrence rate decreased from 6.5 to 3.6%, and the
5-year disease related survival increased from 82.1 to 89.1% Since that time,
multiple studies succeeded in reaffirming the relationship between anatomic-based
colon and rectal cancer surgery and improved outcomes.
Although TME dissection plane in rectal cancer is globally accepted, the
implementation of CME for colon cancer is far less prevalent. It is critical for the
surgeon to understand the anatomic planes to achieve the optimal resected specimen. Achieving this goal requires preoperative discussion with radiologists as well
as postoperative evaluation with the pathologist to provide surgical quality control
and feedback to improve the surgical techniques.
Benign Disease
Complete resection of the mesentery is not required in colon and rectal resections
for benign disease since there is no concern for systemic spread. Thus, in a prophylactic colectomy or proctocolectomy for hereditary colorectal cancer, such as
familial polyposis syndrome or Lyn ch syndrome, performed to prevent cancer
occurrence, CME or TME is not required as long as the presence of cancer has been
ruled out prior to resection (Fig. 36.1). The resection margin may violate the
mesentery, and the resection plane can proceed close to the bowel wall, leaving
behind some of the mesentery.
Colon and rectal resections for inflammatory bowel disease (IBD) also do not
require an oncologic CME or TME. Ulcerat ive colitis is a disease of the intestinal
mucosa, and the mesentery has not been implicated as a factor in disease severity or
outcomes, thus complete resection of the mesentery is not indicated. Although not
ontologically required, during a proctectomy for IBD, the authors recommend
36 Mesenteric Considerations in Surgery of the Colon and Rectum 337
Fig. 36.1 Sagittal (a) and coronal (b) views comparing the dissection planes of TME versus close
rectal dissection. Reprinted with permission, Cleveland Clinic Center for Medical Art &
Photography ©2020. All Rights Reserved
Fig. 36.2 A tumor thrombus
is seen within a mesenteric
vessel that is only 0.1 mm
from the mesenteric surface
dissecting in the avascular TME plane to avoid bleeding associated with diss ecting
through the mesorectum. Crohn’s disease has a characteristic “fat wrapping” of the
mesentery onto the bowel serosa and thickening of the mesentery. When thickening
and foreshortening of the mesentery is extensive, vascular ligation can become
difficult and increase the blood loss, thus resections are classically performed close to
the bowel wall or at a central area of the mesentery apart from the diseased bowel
338 H. Kessler et al.
where inflammation and thickening have not yet arrived. Suture ligation may be
required instead of vascular sealing devices, which more easily ligate vessels in
normal mesentery. Although, Crohn’s disease is conventionally defined a disorder of
the intestine itself, the contribution of hypertrophic mesenteric adipose tissue in the
disease process is under debate. Coffey and colleagues found that ileocolic resections
with a mesenteric excision had a lower rate of recurrence requiring surgery compared to conventional resection next to the bowel wall (10% vs. 30%). More patients
were smokers in the conventional resection group, however, even in multivariate
analysis, mesenteric excision was an independent protective factor. A retrospective
study by de Groof et al. investigating proctectomy without restoration of intestinal
continuity in Crohn’s disease, found a significant increase in perineal wound complications when the mesentery was resected close to the rectum compared to a TME
resection (59.5% vs. 17.6%). A secondary resection of the rema ining mesorectum in
patients with nonhealing wounds resulted in a 75% healing rate. Additionally, the
re-resected mesorectum still expressed higher levels of the proinflammatory cytokine TNFa mRNA, suggesting the remaining mesorectum created a persistent
proinflammatory environment even after resection of the diseased bowel. Further
studies are required to determine the optimal mesenteric resection for Crohn’s disease. These issues are discussed in other chapters in this textbook.
Colon Cancer Principles
In many Western Countries, the survival in rectal cancer has escalated to the extent
that it now exceeds that of colon cancer, due to the improvement in rectal cancer
treatment. There is a wide variation in colon cancer outcomes based upon location,
with conce rn that the surgical quality may be an important variable. One consistent
feature of colon cancer surgical treatment is removal of lymph nodes within the
mesentery along the feeding vessels. The choice of surgical resection is based upon
the location of the tumor. Each tumor has a unique anatomy and drainage, and
therefore the operation needs to be individually tailored. Adjuvant therapy can
improve outcome based upon lymph node involvement and tumor pathology, such
that an ideal mesocolic resection with an increased excision and pathologic evaluation of mesenteric lymph nodes can correctly guides which pati ents should
receive adjuvant therapy.
In Europe, CME and central vascular ligation (CVL) as proposed by Hohenberger have been introduced first. Sharp and careful dissection of the mesocolon’s
visceral plane from the retroperitoneal plane is mandatory to prevent spread of
potentially involved lymph nodes, tumor deposits, or micrometastases in the
mesocolon into the peritoneal cavity. Along with CME, ligating the named vessels
through CVL, also referred to as high vascular ligation, promotes maximal harvest
of regional lymph nodes including those at the root of the mesentery. If the peritoneal surfa ce of the mesentery is penetrated, tumor cells may be disseminated
(Fig. 36.2). Achieving CME and CVL offer the most accurate staging along with
36 Mesenteric Considerations in Surgery of the Colon and Rectum 339
significant survival advantage with decreased local recurrence rates and improved
5-year cancer-related survival rates.
The Stockholm colon cancer project was initiated from 2004–2007 focusing on
interdisciplinary exchange of knowledge and creating multidisciplinary teams.
Improvements targeted more appropriate staging by screening, daytime specialists
performing emergency surgeries, improved surgery by a more complete resection,
maximizing lymph nodes by increasing extent of resection and pathologic evaluation
of nodes in the specimen, and decreasing hospital and surgeon variability through
training and centralization. This project lead to an increase in specimens with >12
lymph nodes from 42.2 to 81.4%, and an increase in the mean number of lymph
nodes from 11 to 18. Overall survival was increased in all stages, and disease-free
survival also improved, which was most pronounced in stage III disease. Thus,
standardization of technique along with CME should be considered for all colon
cancer resections. Examples of resected specimens are shown in Fig. 36.3a and b.
Fig. 36.3 CME specimens
for carcinoma at the splenic
flexure (a) and ascending
colon (b)
a
b
340 H. Kessler et al.
In Japan, the “D3 lymphadenectomy” was described in 1977 and is now the
standard approach there and also in, China, Korea, and Taiwan. The lymph nodes
are described as epicolic and paracolic, D1, intermediate, D2, and central lymph
nodes along trunks of named arteries and veins, D3. This approach focuses more on
anatomic location of the lymph nodes rather than the embryologic dissection
planes, and the D3 lymphadenectomy is recommended in T2–T4 tumors and in
presence of lymph node metastas es. Another difference between D3 lymphadenectomy in Asia and CME and CVL in the Western World is a shorter length
of resected intestine.
The length of resected bowel is largely based upon the goal to obtain adequate
lymph node resection. Initially published in 1983, Jinnai recommended that lymph
nodes 10 cm laterally from the tum or should be resected. Additional studies supported this finding and further characterized that the distance of metastatic lymph
node spread from the tumor increases with an increasing T stage. In a study of
pathological evaluation of resected specimens, in T1 tumors, lymph node metastases were found up to 3 cm from the tumor, while in T3 and T4 tumors, metastatic
lymph nodes were found up to 7 cm from the tumor. Since T stage is difficult to
predict preoperatively, a proximal and distal margin of 10 cm is recommended to
resect all potentially positive lymph nodes.
Studies of Anatomy and Embryology
Surgical embryology and anatomy have a key function for optimized colon cancer
surgery. The primitive gastrointestinal tract in an embryo at 4–6 weeks (Fig. 36.4a
and b) is reduced to a single somatic tube with the visceral peritoneum directly
overlying the gastrointestinal tract and a second external layer, the parietal peritoneum which lines the body wall and associated organs including the retroperitoneal structures. The visceral peritoneum surrounds the somatic tube including the
mesentery containing the vessels from the aorta to the intestines. As the organs
grow, the primitive GI tube is divided into the foregut including stomach and
duodenum, the midgut with jejunum, ileum, ascending and transverse colon, and
the hindgut including left colon and rectum. The intestines grow and twist to
elongate. In some regions of the intestine, the visceral peritoneum fuses with the
parietal peritoneum to become fixed in specific areas. The transverse colon lies over
the duodenum in close proximity to the stomach, and the anatomy in this area
becomes more complex. The greater omentum attaches to the anterior transverse
colon creating the lesser sac. The mesentery in all of these connections is covered
by the visceral peritoneum which can be separated from the adjacent parietal
peritoneum to recreate the embryologic planes (Fig. 36.5). The ascending and
descending colon become fused to the parietal peritoneum lining the body wall
laterally and posteriorly the kidneys and ureters. Toldt’s fascia is a fusion of the
visceral peritoneum of the bowel mesentery and the parietal peritoneum of the
retroperitoneal structures. Gerota’s fascia is a distinct layer overlying the kidney
36 Mesenteric Considerations in Surgery of the Colon and Rectum 341
Fig. 36.4 Embryologic gastrointestinal (GI) tube at 4–6 weeks of life, shown in cross section (a),
and sagittal view after further development (b). The GI tube is a central tube lined by visceral
peritoneum which wraps directly around the visceral organs. The parietal peritoneum is the outer
layer that lines the organs embedded in the body wall. There is a double layer of visceral
peritoneum allowing blood vessels to enter the GI tube from the aorta which will become the
mesentery. The parietal and visceral peritoneum join at the origin of the visceral arteries. Reprinted
with permission, Cleveland Clinic Center for Medical Art & Photography ©2020. All Rights
Reserved
and adrenal glands within the retroperitoneum. The correct dissection planes discussed later in this chapter should be between the visceral and parietal peritoneum,
rather than extending into the retroperitoneum to expose Gerota’s fascia.
Surgical Principles
Preoperative Vascular Anatomical Considerations
A part of the preoperative evaluation of patients with colon and rectal cancer is
staging of the disease in the context of involvement of the mesocolon and
mesorectum. Staging CT scans of the abdomen and pelvis with IV and PO contrast
are indicated for both colon and rectal cancer to identify distant metastases but can
also help identify vascular anatomy as well as potentially enlarged lymph nodes.
MRI has become the recommended modality to stage rectal cancer, which is most
useful in classifying T and N stages, and if adjacent structures are involved by the
tumor. MRI also helps determine whether preoperative radiation is indicated prior