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268 Mesenteric component of rectal resection
(b)
Pe
Mesosigmoidal
Mesosigmoidal mobilization (right/medial aspect)
through what was thought to be the peritoneal reection,
the true peritoneal reection comes into view. Once congenital adhesions are divided, the lateral aspect of the mesosigmoid is always observed, as is the peritoneal reection
at the base of this. Division of the reection (coupled with
the above mesofascial mobilization) means the mesofascial
plane formed by mesosigmoid, and underlying fascia can be
further mobilized (Figure 18.15).
As was the case for the le colon and mesocolon, iden-
tication of the interface enables detachment of the mesosigmoid from the retroperitoneum and retention of the
fascia overlying the retroperitoneum. Many complete this
activity digitally by gently sweeping the fascia posteriorly
and the mesosigmoid anteriorly, and in this manner separate the mesosigmoid as far medially as possible. Complete
Mesosigmoid
mobilization is impeded by the right peritoneal reection at
the right side of the base of the mesosigmoid (Figure18.16).
is is identied by liing the sigmoid and mesosigmoid
anteriorly, o the retroperitoneum, thereby exaggerating the right-sided mesosigmoidal peritoneal reection.
Peritonotomy here joins the lateral to medial and medial to
lateral planes of mobilization (Figure18.16).
At this point, the distal mesosigmoid is now mobile and
it remains to detach the rest of the mesosigmoid. e le
hand is placed underneath the mesosigmoid, to li the adipovascular pedicle forward, and the pedicle is further mobilized until impeded by the origin of the IMA (Figure18.17).
Anavascular interpedicular region occurs proximal to the
IMA pedicle and can be dissected through. is activity
eectively isolates the pedicle for skeletonization, clamping,
(a)
ritonotomy
of peritoneal
reflection
Right
mesosigmoidal
peritoneal
reflection
Peritonotomy
of peritoneal
reflection
(Toldt’s ) fascia
Figure 18.16 Mesosigmoidal mobilization (right/medial aspect). Right-sided peritoneal reection at the base of the mesosigmoid pre (a) and post (b) peritonotomy. (a) To demonstrate the peritoneal reection at the medial (right) side of the
mesosigmoid the sigmoid and mesosigmoid have been retracted anteriorly and to the left, that is, away from the retroperitoneum. (b) When the peritoneal reection has been divided through, the mesofascial interface is identied.
IMA skeletonization and division
(a)
(c) (d)
Clamping of vessel Division prior to suture ligation
rior mesenteric vessel
Open total or partial mesorectal excision 269
Mesosigmoidostomy
Figure 18.17 Isolation (a, b), clamping (c), and (d) division of inferior mesenteric vascular pedicle.
(b)
Isolation of infe
division, and ligation (Figure 18.17). A connective tissue
collar or cu occurs surrounding the vessel formed by
coalescence of Toldt’s fascia and mesenteric connective tissue. is property means the mesentery can be separated
from the vessel (thereby fully skeletonizing it) without damage to the vessel.
There are minor vessels within the connective tis-
sue at the pedicle, and although bleeding from these is
inevitable, it is invariably minor. A more adventurous
dissection through the pedicle can lead to disruption
of the IMA that will bleed extensively unless hemostasis is obtained there and then. The simplest means of
doing this involves placing the index finger of the left
hand around the pedicle, hooking up the pedicle, and
then pinching it between thumb and index finger (Figure
18.17). This stops bleeding, which allows the surgeon
270 Mesenteric component of rectal resection
Posterior mesorectal mesofascial plane
ace/plane
(b)
time to obtain Kelly clamps and 0-0 Vicryl® sutures to
obtain hemostasis (Figure 18.17).
Some surgeons would now divide the proximal sigmoid
and hemostatically divide across the mesosigmoid toward
the cut edge of the IMA pedicle. is has been referred to
as the “division of convenience” and enables the surgeon
reect the sigmoid/mesosigmoidal complex forward, to
expose the posterior mesorectal plane (Figure 18.18).
Mobilization of the le mesocolon, colon, and splenic
exure as well as greater omentum has been described in
detail in the chapter of mesosigmoidectomy (Chapter 17),
and the reader is referred to that chapter for these steps.
At this point, the surgeon packs the divided colon into the
le ank using a large moist swab. Next, the sigmoid and
mesosigmoid are reected anteriorly to expose the mesorectal plane. is has aptly been called the “holy plane”
and is in fact a continuation of the mesofascial plane
(Figure 18.18) [20].
A number of points should be emphasized at this stage.
If the “holy plane” of mesorectal dissection is not apparent,
then it is likely that one has divided through the mesofascial plane. is observation should alert the surgeon to the
possibility that he/she may be retrofascial in dissection and
the ureter compromised. e latter should be identied
and inspected to ensure that it is not in danger of division.
Ifdissection has been conducted as described earlier, then
one will see that peritoneal margins on the le and right
converge at the pelvic brim. From there, they separate as the
right and le pararectal peritoneal reection. e point at
which the peritoneal margins are closest corresponds to the
rectosigmoid junction, the end of the mesosigmoid, and the
start of the mesorectum.
e upper mesorectum is reected forward, placing the
bers of the mesorectal plane under tension (Figure 18.19).
Mesofascial separation here frees the posterior aspect of the
mesorectum from the mesorectal (Toldt’s) fascia. Based on
Posterior
mesorectum
(a)
Interf
}
Mesorectal
(Toldt’s )
fascia
Posterior
mesorectum
Interface/plane
Mesorectal
(Toldt’s )
fascia
Figure 18.18 (See also QR 13.) (a, b) Intraoperative (open) demonstration of posterior aspect of mesorectum and posterior
mesorectal fascia. (a) The rectum and mesorectum are retracted anteriorly. Tension is transmitted to the mesofascial interface and the components here (i.e. mesentery and fascia) can be differentiated. (b) The fascia can then be divided through
to mobilize the mesorectum as an intact mesenteric package.
(a)
(b
Interface/plane
Pararectal peritoneal reflection
Peritonotomy
of right
pararectal
reflection
Mesorectum
Open total or partial mesorectal excision 271
Interface/plane
Right
Side
Mesorectal
(Toldt’s )
fascia
Mesorectum
pararectal
peritoneal
reflection
)
Figure 18.19 Intraoperative (open) demonstration of right (a) (see also QR 2d/5) and left (b) (see also QR 2d/6) pararec-
tal reection undergoing division with exposure of underlying mesofascial interface between mesorectum and adjacent
fascia. To generate these views the mesorectum is retracted away from the pelvis. This places the reection under stretch
and enables its division. The mesofascial plane is apparent after division.
surgeon’s preference, the right or le pararectal reection
is then divided through, thereby exposing the underlying
mesofascial plane.
e mesorectum remains attached laterally, anterolater-
ally, and anteriorly. e lateral and anterolateral aspects of
the mesorectum must then be separated from their pelvic
attachments. is is aided by the fact that a mesorectal plane
occurs circumferentially around the mesorectum. e plane
is partially interrupted at the zone of adherence.
Mobilization of the posterior and posterolateral mesorectum means that the mesorectum can be retracted laterally
or anteriorly. Countertraction can be exerted on the lateral
aspect of the pelvis. is is achieved by placing the lipped pelvic retractor in an anterolateral location and tilting inward.
Left
Left
side
Mesorectal
(Toldt’s )
fascia
e combination of traction (on mesorectum) and countertraction (on pelvic side wall) is essential as it stretches the
mesorectal plane and provides a road map for further dissection. Dissection at this point follows the principles of
mesofascial separation, as elsewhere along the mesentery.
e fascia is swept toward the mesorectum to maintain an
intact package.
e mesorectal plane can be dicult to identify in obese
patients. In these, the normally areolar fascia is attenuated
due to pressure eects, with the result that traction and
countertraction may not lead to identication of the mesorectal plane.
At the zone of adherence, parasympathetic nerves,
lymphatics, and minute vessels approach the mesorectum
272 Mesenteric component of rectal resection
pararec
(b)
Anterior peritoneal reflection
pararec
tangentially. Here, the mesorectal plane is traversed by
these structures. ey represent an attachment that should
not yet be divided at this point.
Once the anterolateral mesorectum has been mobilized
as much as possible, the anterior mesorectum is mobilized.
e rectum is deected posteriorly by pressing back and
up on a moist 4 × 4cm swab on the anterior surface of the
rectum. e lipped pelvic retractor is placed in the anterior
midline and then angled backward so the peritoneal reection is placed under traction (via the rectum) and countertraction (via the peritoneal reection) (Figure18.20). is
in turn exaggerates the peritoneal reection. In the male, a
peritonotomy is made approximately 5mm anterior to the
Right
tal
reflection
reection, and in the female, peritonotomy is conducted
directly through it.
As earlier, the technical goal is the same, that is, mesofas-
cial identication, component separation and detachment of
the mesorectum. Traction and countertraction will demonstrate the mesofascial interface between the mesorectum and
fascia. In the female, the mesofascial interface is repeatedly
demonstrated by retracting the vagina anteriorly and the
rectum posteriorly. ere is a tendency to underestimate the
transverse extent of the vagina, which may be pulled posterolaterally. To prevent digression into the vagina, the surgeon
repeatedly changes position of the lipped pelvic retractor and
his/her position on the anterior surface of the rectum.
Mesorectum
(a)
Left
tal
reflection
Anterior
reflection
Right
pararectal
reflection
Rectum
Figure 18.20 Anterior peritoneal reection. (a) Intraoperative view of the anterior reection as the right-sided pararectal
peritoneal reection is divided onto the anterior component of the reection. To generate this view the rectum and mesorectum are deected to the left. This places the mesofascial interface under tension. In turn, the components of the plane may
be differentiated and separated. (b) (See also QR 2d/7.) Appearance of anterior peritoneal reection after division of right
and left pararectal reection. The midline component of the reection is still intact and is next for division.
Special considerations: Mesorectal obesity in a narrow male pelvis 273
displaced posteriorly
Anterior mesorectal fascia
In the male, anterior peritonotomy coupled with traction and countertraction exposes the mesofascial interface
formed by the mesorectum and fascia. Anteriorly, the seminal vesicles quickly come into view. Posteriorly, the fascia
overlying the anterior mesorectum is frequently referred
to as Denonvilliers’ fascia. e mesofascial plane between
this and the prostate anteriorly is demonstrated with constant traction (posteriorly on the rectum) and countertraction (anteriorly on the prostate) (Figures 18.21 and 18.22).
Dissection here and in this plane will bring the surgeon to
the distal mesorectum where it cones inward.
At this point, the anterior, posterior, and posterolateral
attachments of the mesorectum have been separated. It
remains to detach the mesorectum from the anterolateral
zone of adherence. e zone can be discretely dissected
through using a tissue sealant device such as the harmonic
scalpel. By now, the mesorectum has been detached circumferentially as far as the pelvic oor.
In the distal pelvis and just proximal to the pelvic oor,
Waldeyer’s (or retrorectal fascia) can sometimes cause
confusion. Division through the fascia leads the surgeon
to a potential space that can be somewhat edematous in
appearance.
Using the principles outlined earlier, the mesorectum is
detached from its pelvic attachments to the level of the distal rectum where it tapers inward at the anorectal junction.
e surface of the rectum can be identied by longitudinal
muscular bers. Care is needed here as the bers can be
Mesorectal fascia
Rectum/mesorectum
Figure 18.21 Intraoperative (open) demonstration of the
fascia overlying the anterior mesorectum. The seminal
vesicles and prostate have been retracted anteriorly.
Theanterior mesorectum is demonstrated posteriorly.
The intervening fascia is remarkably thin and very difcult
to demonstrate.
attenuated and the rectal wall quite thin. e rectum is now
ready for division, which can be done using a stapling device
or by simply dissecting across with a scissors if a hand sewn
coloanal or ileoanal anastomosis is envisaged.
SPECIAL CONSIDERATIONS: COLOANAL
ANASTOMOSIS
One of the challenges in conducting a distal anastomosis is
delivering the bowel into the anal canal without traumatizing it. In the case of a coloanal anastomosis, the colon and
mesentery are brought through the anal canal and amputated at a level that permits a tension-free anastomosis.
is is only possible if the entire le mesocolon and splenic
exure have been mobilized fully back to the middle colic
adipovascular pedicle. If there is insucient intestinal and
mesenteric reach, then further mobilization is required.
SPECIAL CONSIDERATIONS: MESORECTAL
OBESITY IN A NARROW MALE PELVIS
Visceral adiposity in the male pelvis presents considerable
technical challenges. is is particularly relevant anterolaterally and in the anterior midline where Toldt’s fascia may
be attenuated to the point of being absent. is may relate to
pressure eects, as the fascia is sandwiched between mesorectal and pelvic side wall adiposity. e resultant problem
is compounded by the length and narrow nature of the male
pelvis. For example, it may be dicult to get a size 6 hand
into the pelvis and exert traction, let alone countertraction. Finally, the zone of adherence can be particularly well
developed in the viscerally obese. is is not helped by the
fact that we, as the surgical community, continue to struggle
with the anatomic properties of this zone. Collectively, the
aforementioned diculties signicantly increase the challenge inherent in identifying the mesofascial plane in the
viscerally obese male.
To cater for this, one approach involves identication of
the mesorectal fascial plane as far anterolaterally as is feasible
(which may not be very far) and to then commence the anterior dissection in the midline as described earlier. is creates a bridge of fatty tissue between the anterior midline and
the anterolateral dissection. Traction on the rectum allows
the surgeon to introduce the jaws of a hemostatic sealant
device across the bridge and the latter can be divided. is
should be done as close to the mesorectum as possible. In
extreme cases, it may not be possible to t the le hand on
the rectum and a retractor in the pelvis for countertraction.
When this is the case, the surgeon should place his/her hand
on the rectum and then slide the jaws of the tissue sealant
device over the ngers. Although this approach is guided
more by feel than by direct view, it will allow the surgeon to
successfully detach the mesorectum. is approach is a last
resort as it is nonanatomic and should be reserved for exceptional circumstances only.
274 Mesenteric component of rectal resection
Mesorectum transection
mesorectum
posterior mesorectum
(c) (d)
Anterior
mesorectum
(a) (b)
Posterior
Divided
mesorectum
Division of
Figure 18.22 (a) Division of anterior mesorectum during partial mesorectal excision. (b) Anterior rectum following
clearance of distal mesorectum. (c, d) Posterior mesorectum prior to and after separation from distal rectum and prior to
division.
References 275
FUTURE DIRECTIONS
Detachment and disconnection of an intact mesorectum
are the cornerstone of safe resection of the rectum. e steps
involved are described above and could help in the international standardization of this procedure. Unfortunately, a
clinical trial is unlikely to be conducted that will denitely
prove the benets of mesenteric versus non-mesentericbased resection of the rectum. at being the case, then
future eorts should focus on an international standardization of the steps involved in mesenteric-based resection of
the rectum.
SUMMARY
e surgical activities required in both open, laparoscopic
and robotic total (and partial) mesorectal excision are based
on mesenteric, peritoneal, fascial, a nd intestinal continuity as
well as contiguity between each of these. e primary goals
are intact detachment and disconnection of the mesorectum
and rectum. ese are achieved by peritonotomy, mesofascial separation, mesenterotomy, and mesenterectomy.
REFERENCES
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2. Coffey, J.C. etal., Mesenteric-based surgery
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3. Coffey, J.C. etal., Terminology and nomenclature incolonic surgery: Universal application of
a rule-based approach derived from updates on
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4. Culligan, K. etal., Review of nomenclature in colonic
surgery—Proposal of a standardised nomenclature
based on mesocolic anatomy. Surgeon, 2013. 11(1):
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6. Schoenwolf, G.C. etal., Larsen’s Human Embryology.
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7. Ackerman, M.J., The visible human project.
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8. The National Library Of Medicine’s Visible Human
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visible_human.html. N.p., 2016. Web April 10, 2016.
9. Coffey, J.C. etal., An appraisal of the computed
axial tomographic appearance of the human
mesentery based on mesenteric contiguity from
the duodenojejunal exure to the mesorectal level.
EurRadiol, 2016. 26(3): 714–721.
10. Peirce, C. etal., Digital sculpting in surgery: A novel
approach to depicting mesosigmoid mobilization.
Tech Coloproctol, 2014. 18(7): 653–660.
11. Hassinger, J.P. etal., Virtual pelvic anatomy
simulator: A pilot study of usability and perceived
effectiveness. J Surg Res, 2010. 161(1) : 23 –27.
12. Gouvas, N. etal., Quality of surgery for rectal
carcinoma: Comparison between open and
laparoscopic approaches. Am J Surg, 2009.
198(5): 702–708.
13. Selvagi, F. etal., Surgical anatomy of the rectum:
Technical notes. G Chir, 1989. 10(12): 747–751.
14. DiDio, L.J. etal., Morphology of the middle rectal
arteries. A study of 30 cadaveric dissections. Surg
Radiol Anat, 1986. 8(4): 229–236.
15. Bilhim, T. et al., Middle rectal artery: Myth or reality?
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subtraction angiography. Surg Radiol Anat, 2013.
35(6): 517– 522.
16. Application of the “Visible Human Project” in
theeld of anatomy: A review. Eur J Anat, 2003.
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17. Moran, B. and R.J. Heald, Manual of Total
Mesorectal Excision. Taylor & Francis Group, Boca
Raton, FL, 2013, pp. 1–31.
18. Heald, R.J. etal., Rectal cancer: the Basingstoke
experience of total mesorectal excision, 1978–1997.
Arch Surg, 1998. 133(8): 894–899.
19. Jessop, J., C. Beagley, and R.J. Heald, The Pelican
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Mesenteric component of right colectomy
J. CALVIN COFFEY AND STEVEN D. WEXNER
19
Aim 277
Introduction 277
Anatomy 277
Open right mesocolectomy 278
Minimally invasive right mesocolectomy 284
Introduction 284
The perpetual obstacle to human advancement
is custom
John Stuart Mill
AIM
To demonstrate the importance of peritoneal and mesentericbased 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 emergence 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
Medial-to-lateral mesenteric detachment 285
Lateral-to-medial mesenteric detachment 287
Special considerations 290
Future directions 291
Summary 291
References 291
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 suer from the fact that there is no anatomic boundary demarcating the termination of the small intestinal
mesentery and the commencement of the right mesocolon
(Figure 19.1). More recently, the term modied 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 manner, one builds a composite anatomic picture that in turn
helps rationalize the procedural steps required to detach
and disconnect the mesentery during right mesocolectomy.
277