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238 Mesenteric component of sigmoid colectomy
Exposed/mobilized
retroperitoneal fa
(a)
retroperitoneal fat(b)
Undersurface of left mesocolon (laparoscopic surgery)
Prior to vascular division the surgeon is advised to have
a clip application device available. at way, any residual
bleeding from the staple-divided edge of the vessel can
be promptly controlled. Persistent bleeding at this point
requires that the pedicle stump be gently grasped (using an
atraumatic grasper) and suture loop placed and snugged
securely. Analternative is to place a Babcocks clamp around
the pedicle prior to its division. If there is residual bleeding,
this can be promptly controlled with the clamp while a clip
applicator is prepared for denitive haemostasis.
Mesocolon pre mesofacial seperation
Aer IMA division, the upper region of the opera-
tive eld is occupied by the le mesocolon, the interface
between it, and underlying fascia (i.e., the mesofascial
interface). elower part of the operative eld is occupied
by the retroperitoneum and overlying fascia (Figure 17.4).
Further dissection involves liing the mesocolon anteriorly and displacing Toldt’s fascia posteriorly. e resultant
“mesofascial separation” is continued as far cephalad and
lateral as possible, leading to le mesocolic mobilization.
Laterally, the colon is reached and colofascial separation
Left mesocolon
from below
Fascia overlying
t
Mesocolon post mesofacial seperation
left mesocolon
Fascia overlying
Figure 17.4 (a) (See also QR 6/2.) Intraoperative view of the mesocolon (above) and fascia (below) as seen during lapa-
roscopic mobilization of the mesocolon off the underlying fascia (and hence retroperitoneum). When the mesocolon is
retracted away from the retroperitoneum the fascia is seen to ride up onto the undersurface of the mesocolon and must
be gently swept away to achieve mesofascial separation. (b) Similar point of view showing the exposed surface of the
leftmesocolon after the fascia has been separated from it.
Open mesosigmoidectomy 239
exposes the le peritoneal reection. is attachment is
retained for the present as it prevents the colon falling into
the operative eld.
e le mesocolon is then divided across toward the
colon (i.e., mesenterotomy). Lateral to the duodenojejunal
exure, the inferior mesenteric vein (IMV) will be encountered. Skeletonization and division are completed using the
steps described earlier in management of the IMA adipovascular pedicle. Once divided, the avascular interpedicular
region of the le mesocolon is apparent and can be quickly
divided through until the intestinal margin of the mesentery
is reached. e focus of dissection returns to the mesosigmoid, and medial to lateral mobilization of this follows the
same principles of mesofascial separation. When complete,
only the lateral peritoneal reection at the base of the mesosigmoid remains to be divided. Peritonotomy is temporarily
deferred as the reection suspends the mesosigmoid, thus
preventing it from falling into the operative eld.
e 30° lens is reoriented to visualize the peritoneal
reection at the lateral aspect of the mesosigmoid and
descending colon. is continuous structure is divided
using the sealant device or a scissors with minimal bleeding (minor vessels occur in the submesothelial connective
tissue). Peritonotomy is continued as far proximally as the
splenic exure. By now, the intestine and mesentery from
the splenic exure to the rectosigmoid junction have been
fully detached from the posterior abdominal wall.
It is usually necessary to mobilize the upper part of the
rectum as part of mesosigmoidectomy. e mesofascial plane
used to mobilize the le mesocolon and mesosigmoid is continued distally beneath the mesorectum. e right and le
pararectal peritoneal reections are divided, thereby exposing
the underlying mesorectal/fascial interface and component
separation here leads to mobilization of the upper rectum.
Although splenic exural mobilization is not an absolute
requirement, some do this routinely to be certain of adequatei ntestina l and mesenteric reach. e patient is placed in
the reverse Trendlenberg position, and the greater omentum
is grasped just distal to the gastroepiploic arcade by both the
assistant and surgeon (Figure 17.5). Tissue sealant devices
can be used to dissect directly through the greater omentum and enter the lesser sac. e dissection is then continued across the greater omentum toward the splenic exure.
At the exure, the greater omentum and the splenocolic
reection coalesce to a variable degree. e resultant complex is directly divided through until the cephalad aspect of
the transverse mesocolon is reached. e colon in the region
of the splenic exure can then be gently grasped (using an
atraumatic grasper) and retracted toward the patient’s right.
In doing this, tension is transmitted to the mesocolon and
thereaer to the mesofascial interface (Figure 17.6). is
activity demonstrates the colo- and mesofascial interface
at the exure, and component separation of each interface
leads to full mobilization of the splenic exure.
e surgical focus returns to the rectosigmoid region
where the mesosigmoid continues as the mesorectum. Many
surgeons will aim to ensure sucient gastromesenteric
length for a tension-free colorectal anastomosis and will
mobilize the upper rectum (see earlier). Following mobilization the nal stage involves mesenterotomy of the mesorectum for which a number of approaches can be adopted.
One approach involves direct dissection across the mesorectum using a tissue sealant device such as the Harmonic®
scalpel or a vessel sealer under high magnication and close
view. e latter are important as the superior rectal artery
and vein will be encountered and should be skeletonized
and divided. ey are generally small enough in diameter
for hemostatic division with the vessel sealer or other tissue
sealant devices. eremainder of the mesorectum can then
be divided across to the serosal surface. Once mesenteric
fat has been cleared from the serosa, the rectum is divided
using an appropriate linear stapling device (see Chapter 15
on instrumentation).
A short Pfannenstiel incision is made and the intestine
and mesentery exteriorized through a wound retractor. As
the mesentery has been fully mobilized, tension should be
minimal. e previous approach also ensures adequate
bowel length should a more distal (even coloanal) anastomosis be required. e proximal resection margin is identied and the mesenterotomy completed to the serosal surface
using a bovie or tissue sealant device. At the proximal colic
margin, it is important to assess for adequate mesenteric
vascularity. An artery clip is placed distally while the proximal mesentery is sharply divided. e result should be brisk
and pulsatile mesenteric bleeding that requires direct control with application of a further clip or ligature. Mesenteric
(and not mucosal bleeding) is regarded by many as the most
important determinant of adequate anastomotic vascularity.
e proximal intestinal margin must be prepared for anastomosis by clearing the serosa of mesentery. is ensures all
bowel wall layers are visible for anastomosis (see Chapter 16).
OPEN MESOSIGMOIDECTOMY
Even in open surgery, minimization of the laparotomy is
preferable as an infraumbilical incision is associated with
less postoperative pain and earlier recovery [20]. In this
context, it is important to evaluate the preoperative CT
abdomen and review the lesion for resection and the clinical context. For example, the mesenterectomy required
in benign disease (e.g., Crohn’s disease or short segment
diverticulosis) can be limited, while the oncologic mesenterectomy must be extensive to ensure adequate lymphadenectomy. If access to the root of the IMA pedicle and IMV
are required, then an extensive midline laparotomy may
be necessary. At open surgery, mobilization of the splenic
exure is impeded when mesenteric access is impeded, and
rather than representing a technical inadequacy, an appropriately sized laparotomy is the safest and optimal approach.
e techniques of ensuring adequate access to the
mesocolon, and mesosigmoid have been dealt with in detail
elsewhere but will be briey touched on here. A reliable
self-retaining retractor is required and examples include
theGusset, Omni-Tract®, or Bookwalter® retractor. e time
240 Mesenteric component of sigmoid colectomy
Divided edge
transverse mesocolon
(b)
Direc
Entry into lesser sac (laparoscopic surgery)
tion of upward traction
Attenuated
greater
omentum
(a)
Divided edge of
greater omentum
Direction of upward traction
Greater
omentum
of greater
omentum
Upper surface of
Figure 17.5 (a) (See also QR 2/9.) Intraoperative appearance of the greater omentum after being retracted upward,
grasped at a secondpoint, and then splayed open for division, during laparoscopic splenic exure mobilization. The
greater omentum canthen be directly dissected through in a hemostatic manner. If this is completed just outside the
gastroepiploic arcade (i.e.,where omental adhesions to the underlying mesocolon are minimal), the lesser sac is safely
entered. (b)Intraoperative laparoscopic view of the lesser sac after omental division. The divided edge of the omentum is
apparent. The upper surface of the transverse mesocolon is also evident. There are minimal adhesions between omental
and mesocolic surfaces.
Spleen
Toldt’s fasciaMesentery
(b)
The splenocolic peritoneal reflection (laparoscopic surgery)
Open mesosigmoidectomy 241
Greater
omentum
Splenocolic
peritoneal
reflection
Divided edge
of greater
omentum
Mesocolon at flexure
(a)
Fascia over
retroperitoneum
Spleen
Greater
omentum
coalesced with
splenocolic
peritoneal
reflection
Remnant of
splenocolic
peritoneal
reflection
Fascia over
retroperitoneum
Figure 17.6 (a) (See also QR 2/5.) Intraoperative appearance of the mesofascial plane at the splenic exure. The plane
here, as elsewhere, is formed by the mesenteric component of the exure and contiguous Toldt’s fascia. The greater
omentum is apparent with the spleen located above it. The splenocolic peritoneal reection is less readily apparent as
theoverlying omentum has coalesced with it. (b) Similar view to (a) after further mobilization involving division of the
splenocolic peritoneal reection and separation of the mesocolon from contiguous fascia.
242 Mesenteric component of sigmoid colectomy
C
Duodenum
(b)
Congenital adhesions (open surgery)
(a)
spent in setting up the latter is justiable, as the retraction
provided and mesenteric access are excellent. is combination is essential in achieving the goals of mesenteric-based
colorectal surgery, and concurrently facilitates education of
these principles.
Important initial steps are aimed at setting up the opera-
tive eld; these involve mobilization of the small bowel and
its mesentery o the le mesocolon, and liing the mesosigmoid out of the pelvis. e small intestine and mesentery
can either be tucked away using a large moist swab in the
Left
mesocolon
ongenital
adhesions
right upper quadrant or exteriorized and held in place again
with a moist swab and large Deaver retractor. It is frequently
necessary to divide adhesions that tether nearby structures
(including the fourth part of the duodenum) to the le-sided
mesocolon (Figure 17.7).
In general in open mesosigmoidectomy, most adopt a
lateral to medial approach starting by dividing congenital
adhesions between the lateral aspect of the mesosigmoid and
parietal peritoneum (Figure 17.8). is provides access to the
base of the lateral aspect of the mobile mesosigmoid where
To feet
To head
To head
Duodenum
To Feet
Figure 17.7 (a) Intraoperative appearance of the adhesions that frequently occur between the duodenojojeunal exure
and the left mesocolon, as observed during an open procedure. The view is from above down. (b) (See also QR 2/10.)
Further example of relationship of the left mesocolon to the fourth part of the duodenum (view from below upward).
Themesocolon can be separated from the adjacent duodenum via mesofascial separation.
(a)
(d)(c)
descending colon
Congenital adhesions (open surgery)
Left
iliac f
ossa
Congenital adhesions
Distal
Proximal
(b)
Divided
congenital
adhesions
Open mesosigmoidectomy 243
Peritoneal reflection
Distal
Left
iliac fossa
Junction between
sigmoid and
Proximal
Toldt’s fascia
Left mesocolon
Figure 17.8 (See also QR 2d/1,2.) (a) Congenital adhesions at the lateral aspect of the mesosigmoid (view from above
down). (b) Following division of congenital adhesions the peritoneal reection at the lateral aspect of the mesosigmoid
becomes apparent. (c)Identication of the left peritoneal reection at the junction between the descending and sigmoid
colon. (d)Identication of the mesofascial interface after division of the left peritoneal reection.
it curves down and becomes attached or apposed to the
posterior abdominal wall. If the peritoneal reection atthe
lateral aspect of the mesosigmoid is divided (Figure17.8),
the mesofascial interface is visualized and component separation can be conducted to mobilize the mesosigmoid. isis
oen easier saidthan done as the mesosigmoidal fascia is
remarkably thin here and can easily be missed. A medial to
lateral approach is favored for neoplastic disease to minimize
manipulation of the tumor and permit early vascular and
venous drainage control.
244 Mesenteric component of sigmoid colectomy
retroperitoneum
l
Mesofascial plane (open surgery)
Subfascial structures
Toldt’s fascia
Mesofacia
interface
Mesosigmoid
(lateral aspect)
Figure 17.9 (See also QR 2d/8,9.) Intraoperative view of the
mesosigmoid and mesosigmoidal fascia. Mesofascial separation involves separation of both and mobilizes the mesosigmoid from the underlying fascia and retroperitoneum.
Fascia overlaying
Given the diculty associated with identifying the meso-
fascial interface in this region, most tend not to divide the
peritoneal reection at this particular level. Instead they li
the junction between the sigmoid and the descending colon
forward. Peritonotomy here exposes the junction between
the colon and underlying fascia and more readily enables
colofascial separation (Figure 17.8c and d). Colofascial sepa-
ration exposes the mesofascial interface and components of
this are separated. is mobilizes the distal le mesocolon,
and once the correct plane has been identied, it can then
be developed distally under the mesosigmoid (Figure 17.9).
Further caudal mobilization requires division of the lat-
eral peritoneal reection, mesofascial separation, and liing
of the mesosigmoid forward o the fascia. e fascia underlying the mesosigmoid is areolar in nature and less distinct
(compared with that beneath the le mesocolon). us, it is
relatively easier (even for experienced surgeons) to digress
into an intra-mesosigmoidal or retrofascial plane, in this
region (Figure 17.10). is risk increases in local inamma-
tion where the mesosigmoid, fascia, and underlying retroperitoneum densely adhere. Intramesosigmoidal dissection
is followed by increased bleeding. Retrofascial dissection
exposes bers of the iliopsoas muscle. Many trainees (and
sometimes experienced surgeons) commence attempts at
mesosigmoidal mobilization in this region and inevitably
end up excavating through to inappropriate planes. is
can be avoided by commencing mesosigmoidal mobilization at the level of the distal descending colon, as described
earlier.
Ureter
Minute vessel in Toldt’s fascia
Figure 17.10 Demonstration of relationship between
retroperitoneal structures (i.e., ureter and gonadal vessel)
to overlying mesosigmoidal (Toldt’s) fascia. Once the
surgeon conducts a mesofascial separation then the fascia
is not breached and all retroperitoneal structures are
safeguarded.
Gonadal vessel
Lateral to medial mesosigmoidal mobilization is continued as far medially as possible until the peritoneal reection
at right side of the mesosigmoid impedes further progress
(Figure 17.11). At this point, the sigmoid and mesosigmoid
are placed under anterior tension, thereby transmitting
tension to the mesofascial interface and exaggerating the
peritoneal reection. Peritonotomy here exposes the mesofascial interface and component separation joins the lateral
and medial plane of dissection (Figure 17.12). e surgeon
then places his or her le hand and index nger through the
window so created to li the adipovascular pedicle containing the IMA forward. is permits further mobilization of
the adipovascular pedicle o the retroperitoneum up to the
level where the IMA curves down on to the aorta. Next the
avascular mesenteric region proximal to the IMA is identied and divided, further isolating the IMA within its pedicle. e IMA can be fully skeletonized, clamped, divided,
and suture ligated with 0-0 Vicryl
®
sutures (Figure 17.12).
It is important to recognize and avoid the sympathetic
nerve bers in the para-aortic area at this level.
Le mesocolic mobilization is progressed by separating
the le mesocolon o the underlying fascia and continuing
this as far cephalad as possible. In open cases, one can place
one’s le hand under the le mesocolon and use the right
to sweep the mesocolon away from the mesofascial interface
Mesofascial separation (open surgery)
c
(c)
(a)
Open mesosigmoidectomy 245
Mesosigmoid
Peritoneal
reflection
Inferior mesenteric
adipovascular
pedicle
Peritonotomy
of peritoneal
reflection
Mesosigmoidal
(Toldt’s ) fascia
(b)
Mobilized
inferior mesenteri
adipovascular
pedicle
Figure 17.11 (See also QD3d/1,2 and QR 2/11.) Medial (right) side of mesosigmoid before (a) and after (b) peritonotomy
and mesofascial separation. (c)When mesofascial separation is complete the inferior mesenteric adipovascular pedicle is
fully mobilized.
246 Mesenteric component of sigmoid colectomy
Inferior mesenteric artery
(a)
(b
(c)
Clamping of
inferior
mesenteric
artery
Division
)
Ligation
Figure 17.12 Inferior mesenteric vessel after skeletonization (a), clamping (b), division, and ligation (c).
Mesofascial interface between the left mesocolon and underlying fascia
mesocolon
(b)
(a)
Open mesosigmoidectomy 247
Left
(undersurface)
Mesofascial
interface
Mesocolic
(Toldt’s )
fascia
Left mesocolon
(undersurface)
Mesofascial
interface
Mesocolic
(Toldt’s )
fascia
Figure 17.13 (See also QR 6/2.) The mesofascial interface between the left mesocolon and underlying fascia before (a) and
after (b) hemostatic mesofascial separation. In (a) the mesocolic fascia (Toldt’s fascia) is pulled up onto the undersurface
of the leftmesocolon. In (b) the fascia has been separated from the mesocolon and the latter mobilized. By repeating this
process the left mesocolon is fully mobilized.
until the le mesocolon has been fully free up to the splenic
exure (Figure 17.13). In fact, the mesenteric component
of the splenic exure can also be mobilized in this manner.
Ultimately, the surgeon enters the lesser sac where he/she
will be impeded by the apposition of the greater omentum
to the cephalad aspect of exural and transverse mesentery.
Mobilization of the le colon proceeds as far as the
splenic exure by dividing the le peritoneal reection and
congenital adhesions. e latter can be prominent just distal
to the exure. It is usually possible at this point to insinuate the ngers of the right hand underneath the splenocolic
reection and then diathermy divide the latter onto one’s
nger. is action divides the peritoneal component of
theexure. Peritonotomy exposes the underlying colo- and
mesofascial planes. Separation of planar components completes mobilization of the splenic exure.
Increasing volumes of visceral adiposity mean that omen-
tal mobilization from the transverse mesocolon and colon is
required to achieve complete mobilization of the splenic exure. To achieve this, the surgeon stands between the legs and
the patient is placed in the slight head up position. e peritoneal reection between the greater omentum and transverse
colon is divided and adhesions between the greater omentum
and transverse colon divided (Figure 17.14). While applying
downward traction on the transverse colon/mesocolon and
upward traction on the greater omentum, separation of both
is continued laterally as far as the splenocolic reection. At
the exure, the greater omentum and splenocolic reection