腹腔镜下乙状结肠癌（图文演示）

中文版：腹腔镜下乙状结肠癌（中文图文演示）

LAPAROSCOPIC   SIGMOIDECTOMY   FOR   CANCER
Authors
J Leroy, J Okuda, J Milsom
Abstract
The description of the laparoscopic sigmoidectomy for cancer covers all aspects of the surgical procedure used for the management of sigmoid colon cancer.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: exploration, exposure, vascular approach, mobilization of sigmoid colon, division of sigmoid colon, mobilization principles, lateral mobilization, medial mobilization, extraction of sigmoid colon, preparation of anastomosis, anastomosis.
Consequently, this operating technique is well standardized for the management of this condition.

1. Introduction
The sigmoid colon is the most frequent location for colon cancer. Sigmoid colon resection is the first line treatment in most cases of sigmoid colon cancer. A laparoscopic approach may be used to perform sigmoid resection in a manner equivalent to the open technique. Indeed, most laparoscopic surgeons consider laparoscopic sigmoidectomy relatively straightforward.
Laparoscopic sigmoid colon resection for cancer was described in a standardized manner as early as 1994 (Geis et al., 1994). Nevertheless, it should be reserved for highly skilled surgical teams participating in controlled multicenter studies.

2. Anatomy

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The sigmoid colon is the mobile terminal portion of the left colon. Except in advanced stages of cancer, the mobility of the sigmoid colon depends on the length of the sigmoid loop and on cancer-associated pathologies such as diverticulosis.
The vascular supply of the sigmoid colon is based entirely on the inferior mesenteric artery and its branches. Thorough knowledge of the vascular anatomy and its variations is essential for a safe resection.
The close proximity of the vessels to the left sympathetic trunk and the left ureter represents potential risks in sigmoid colon resection.

• Arteries

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The arteries are all branches of the inferior mesenteric artery (IMA).
1. Inferior mesenteric artery (IMA)
2. Left colic artery (LCA)
3. Trunk of sigmoid arteries
4. Superior rectal artery (SRA)
5. Marginal arteries

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The inferior mesenteric artery (IMA) originates from the anterior surface of the abdominal aorta, 1 to 3 cm below the third portion of the duodenum, to form the main blood supply of the left colon. It gives off branches for the left colon, the sigmoid colon, and the rectum.

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The left colic artery (LCA) is the first branch of the IMA and supplies the vasculature of the left colon. After crossing over the inferior mesenteric vein (IMV), the LCA courses along the IMV’s left border for a variable distance. It then approaches the marginal arteries, which it generally joins somewhere between the splenic flexure and the transverse colon. Its preservation is possible during mobilization of the left colon.

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There are at least 3 sigmoid arteries (SA), often originating from a common trunk distal to the LCA. Variations are common. These sigmoid branches can originate separately from the IMA up to the promontory or from the LCA. They are always situated medial to the sigmoid veins and posterior to the superior rectal vein.

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The superior rectal artery (SRA) is the terminal branch of the IMA. It is located just anterior to the fascia propria of the rectum at the rectosigmoid junction. It gets progressively closer to the rectal wall as it divides into a right and a left branch, or into even more branches in 17% of cases (Ayoub, 1978). These branches supply the upper two thirds of the rectum. The larger right branch often extends from the IMA (Ayoub, 1978). These 2 branches divide 2 or 3 more times without anastomosing and end on the pelvic floor. All these arterial branches remain in the mesorectum along with the rectal veins, which drain into the superior rectal vein (SRV) and then into the IMV.

• Veins

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Rectal, sigmoid, and left colic veins join to form the inferior mesenteric vein (IMV).
1. Inferior mesenteric vein (IMV)
2. Left colic vein (LCV)
3. Trunk of sigmoid veins
4. Superior rectal vein (SRV)
5. Marginal veins

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The sigmoid and left colic veins join to form the inferior mesenteric vein (IMV).
1. Portal vein
2. Splenomesenteric trunk
3. Splenic vein
4. Inferior mesenteric vein (IMV)
5. Superior mesenteric vein (SMV)

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There are several sigmoid veins (SV). They run separately or as a common trunk into the SRV to form the IMV.

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The left colic veins (LCV) often join into a main trunk. There are often 2 LCVs for 1 LCA. Accessory venous branches, originating from the descending colon, run directly into the IMV. They must be divided to allow mobilization of the left colon.

3. Operating room set-up

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It is essential that the patient be appropriately positioned to avoid complications (nerve and vein compression, injuries to the brachial plexus) and to facilitate the procedure and anesthetic monitoring.
- Trendelenburg position with a 15° to 25° tilt and a 5° to 10° right tilt;
- lithotomy position;
- buttocks placed at the distal edge of the table;
- thighs and legs stretched apart with a slight flexure;
- right arm alongside the body;
- left arm at a right angle or alongside the body (surgeon’s preference);
- gastric tube and urinary catheter;
- heating device.

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1. Surgeon
2. First assistant
3. Second assistant
4. Scrub nurse
5. Anesthesiologist
Although the procedure can be performed with a single assistant, it is preferable to have 2 assistants and a scrub nurse, especially when experience in performing the procedure is limited.
The team can remain in the same position throughout the entire procedure.

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- The table must allow for both abdominal and perineal access. It is advisable to use a table that can be easily tilted laterally and placed into steep Trendelenburg and reverse Trendelenburg position, facilitating perineal exposure.
- The laparoscopic unit is located to the left of the patient along with the main monitor. It may be useful to use a second monitor placed above the patient's head.
- To perform the procedure in excellent conditions, a 3CCD camera is mandatory.
- A high output (>= 9L/min) insufflator should be used to electronically monitor pressures. Its inertia should be low to make up for losses in carbon dioxide (induced or not).
- Voice-controlled robotic arm
1. Laparoscopic unit
2. Electrocautery
3. Operating table
4. Monitor
5. 3CCD camera
6. Instrument table

4. Trocar placement

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Although a sigmoidectomy can be performed using only 3 trocars, for complicated presentations and especially when the surgeon’s experience in performing the technique is limited, the use of more trocars is preferable. This helps to ensure the safety of the procedure by allowing improved exposure of the operative field and the mesentery, and by facilitating mobilization of the splenic flexure.
We readily use 6 trocars, with a trend toward reducing trocar size. The patient’s body habitus, previous surgical history and the initial laparoscopic exploration via the supraumbilical trocar should be used as guides for introducing the various operating trocars.

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Firm trocar fixation in the wall is important. This is achieved by adapting the size of the incision to the trocar and, if needed, fixing the trocar to the abdomen with a suture. We no longer use screw-like devices, as they increase parietal trauma.

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Trocar A: 10/12 mm, 0° optical
The trocar is positioned on the median line 3 to 4 cm above the umbilicus or 20 cm above the pubis in patients with a small stature.
This trocar accommodates a 0° optical.

• Operating

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This is a 5 mm operating trocar, used for retraction during mobilization of the splenic flexure (caudal retraction of the left colon), during which time trocar D is used for operating instruments. At the end of the procedure, Trocar B may be replaced by a 12 or 15 mm trocar for introduction of a linear stapler.
It is situated on the right midclavicular line, at the level of the umbilicus.
This trocar accommodates an atraumatic grasper.

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This is a 5 mm operating trocar, used for retraction during mobilization of the splenic flexure (caudal retraction of the left colon). At the end of the procedure, it may be replaced by a 12 or 15 mm trocar for introduction of a linear stapler.
It is situated on the right midclavicular line, 8 to 10 cm below trocar B.
This trocar accommodates:
- scissors (monopolar, high-frequency hemostasis device, clip, staplers), bipolar hook, surgical loop, suction-irrigation device;
- an atraumatic grasper.

• Retractors

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This is a 5 mm retractor, except during mobilization of the splenic flexure, when it is used as an operating trocar.
It is situated on the left midclavicular line, at the level of the umbilicus.
This trocar accommodates:
- an atraumatic grasper;
- scissors (monopolar, high-frequency hemostasis device, clip, staplers), bipolar hook, surgical loop, suction-irrigation device.

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This is a 5 mm retractor, except during mobilization of the splenic flexure when it is used as an operating trocar. It accommodates a grasper used to expose the sigmoid mesocolon and left mesocolon.
It is situated 8 to 10 cm above the pubis on the median line.
This trocar accommodates a grasper and a suction-irrigation device.

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This is a 5 mm retractor that accommodates an atraumatic grasper used to laterally retract the terminal portion of the small intestine and to better expose the attachments of the omentum to the transverse colon during mobilization of the splenic flexure.
It is situated on the right midclavicular line in the subcostal position.
This trocar accommodates an atraumatic grasper.

5. Instruments

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Most authors use laparoscopes with 0° and 30° visual axes and with a 70° visual field.
Some authors use a laparoscope with a 45° visual axis.

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1. Grasper
2. Bipolar
3. Ultrasonic dissectors
4. Linear stapler
5. Scissors
6. Clip applier
7. Circular stapler
8. Plastic-coated drape to protect the incision after freeing the colostomy

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1. Flexible retractor
2. Peanut swab

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Efficient suction-irrigation device for lavage and dissection (lysis of adhesions)

6. Exploration

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As with open surgery, all laparoscopic procedures begin with an exploration of the abdominal cavity. The exploration is panoramic. Visceral organs may be manipulated with blunt instruments to complete the exploration. This can be combined with an ultrasound examination of the liver to search for associated pathologies that may contraindicate the laparoscopic procedure.

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Exploration of the liver is associated with an ultrasound examination. Considered mandatory in oncology for some authors (Milsom), it is performed with a flexible 10 mm catheter. It can supplement preoperative imaging studies, especially if a surgical liver procedure is performed during the same operation.

7. Exposure

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Improved exposure greatly facilitates the surgical procedure.
Proper exposure is a function of a host of factors. These include the working space in the abdominal cavity, the quality of the preoperative gastrointestinal (GI) preparation, the positioning of the patient as well as a perfect understanding of the organization of the operating field.

• Working space

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The working space depends on the quality of the preoperative GI preparation, the positioning of the patient and complete relaxation allowing the abdominal wall to distend correctly under the pressure of the pneumoperitoneum.

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An empty digestive tract facilitates the layering of intestinal loops. It is achieved by a strict, fiber-free diet 3 to 8 days prior to surgery.
As most experts do, polyethylene glycol is no longer used before surgery to complete the intestinal preparation.
The day before, or even on the day of the operation, the patient is placed on a fibre-free diet and undergoes enemas.

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To prevent the patient from sliding, shoulder supports or straps around the thorax may be used.
In our current practice, we rarely use such measures, despite a 20° to 30° Trendelenburg position and a right tilt.

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In addition to the pressure of the pneumoperitoneum (12 mm Hg), complete relaxation of the muscular wall is essential to create the working space.

• Layering intestinal loops

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Layering the intestinal loops requires gravity and retraction of organs.

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The greater omentum and the transverse colon are placed in the left subphrenic region and maintained in this position by the Trendelenburg tilt. An atraumatic retractor, introduced through trocar D, may also be used.

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The jejunum is retracted toward the right hypochondrium, below the right transverse colon. The right tilt and Trendelenburg position, along with an atraumatic retractor if needed, maintain the small intestine in this position.

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The distal portion of the small intestine is placed in the right iliac fossa along with the cecum. If the small intestine is too bulky, this operative maneuver can be difficult, notably in obese patients.

• Specific cases

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Obesity characterized by a flaccid muscular wall (female patients) is not a major handicap as ample working space remains. In the setting of a tonic muscular wall (male patients) and short, fatty mesenteries, the surgeon must progressively layer the intestinal loops to expose the dissection areas.

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By freeing the digestive tract, layering can be performed for better exposure of the operating field. It is sometimes useful to preserve adhesions, especially at the level of the cecum or the splenic flexure.

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The uterus may be an obstacle to adequate exposure in the pelvis. In postmenopausal female patients, the uterus can be suspended to the abdominal wall by a suture. This suture is introduced halfway between the umbilicus and the pubis to suspend the vagina and make it horizontal, thereby opening the rectovaginal space.

8. Vascular approach

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The initial vascular approach makes it possible to dissect the sigmoid mesocolon posteriorly and medially without manipulating the colon and the tumor. It must be associated with a lymphadenectomy, removing the lymph nodes of the inferior mesenteric chain.
Except in simple cases where vessels are visible due to transparency, the vessels are gradually exposed once the peritoneum of the sigmoid mesocolon has been widely opened.
Before dividing the vessels, it is important to identify the sympathetic nerve plexus trunks and the left ureter in order to preserve them.

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The peritoneum is opened upward along the right anterior border of the aorta, starting the incision from the promontory and extending it to just below the third portion of the duodenum.
Anterior traction of the sigmoid mesocolon, using a grasper introduced through trocar E, exposes the base of the sigmoid mesocolon. The pneumodissection (entry of CO2 into the retroperitoneal space), which results from the pneumoperitoneum, facilitates the dissection.

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Dissection of the fatty cellular tissue is pursued upward and from right to left by gradually dividing the sigmoid branches of the right sympathetic trunk to expose the origin of the IMA.
This operative step is essential as it allows a safe dissection of the IMA at its origin.

• Division of IMA/branches

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To remove the lymph node tissue, the IMA is dissected 1 to 2 cm in a circular fashion before clipping.
A more extensive dissection can also be performed. The IMA is skeletonized and the left colic artery is identified and isolated in order to be preserved.

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A gold standard in cancer, it involves a risk of injury to the left sympathetic trunk situated on the left border of the IMA. A meticulous dissection of the artery to apply clips before division is the only way to avoid this risk.
Dissection performed close to the artery has a low risk for damaging the left ureter if clips are used to ligate the IMA.

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This allows preservation of the vascular supply of the left colon, but it can limit the mobility of the left colon. The sympathetic nerve trunks situated to the left of the IMA must be preserved.
If clips are used, the ureter must not be visible before ligature and division of the artery.

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The IMV is identified to the left of the IMA or in case of difficulty, higher, to the left of the ligament of Treitz (duodenojejunal flexure). It is then crossed anteriorly by the LCA, which then runs along its left border. The IMV is divided below the inferior border of the pancreas or above the left colic vein.

9. Mobilization/sigmoid

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Mobilization of the sigmoid colon follows the division of the vessels.
This step includes the freeing of posterior and lateral attachments and the division of rectal and sigmoid mesenteries.
The approach is either medial or lateral. We prefer using the medial approach, except in thin patients whose sigmoid colon is very mobile. The medial approach is well adapted for laparoscopy as it preserves the working space and demands the least handling of the sigmoid colon.

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A medial approach is used.
After division of the vessels, the sigmoid mesocolon is retracted anteriorly (trocar E) in order to open the posterior space. The plane between Toldt’s fascia and the sigmoid mesocolon can then be identified. This plane is avascular and easily detached. It is exposed when the dissection is pursued posterior to the sigmoid mesocolon (not laterally nor to the left of the aorta).
The dissection is pursued laterally to Toldt’s line, posteriorly and external to the colon.
The left sympathetic nerve trunk, the ureter and genital vessels, covered by Toldt’s fascia, are viewed internally to externally during dissection.
The lateral attachments can then be divided using a lateral approach.

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Cylindrical, retrovascular division is used to resect the freed upper portion of the mesorectum.
The use of ultrasonic dissectors or a high frequency hemostasis device can facilitate this act. Nevertheless, the surgeon must be careful in the left region: the mesorectum there is closely attached to the left lateral fascia where the superior hypogastric nerve and the left ureter are situated.
The superior rectal vessels are again divided in the mesorectum.

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The sigmoid loop is pulled toward the right hypochondrium (grasper in trocar F) to exert traction on the left layer of the sigmoid mesocolon.
The base of this layer is opened toward the paracolic gutter and the pelvis. In case of adhesions of the sigmoid colon to the abdominal wall, this operative step can be difficult.
After incision of the left layer of the sigmoid mesocolon, the medially performed posterior detachment is joined. During this step, care must be taken to avoid genital vessels and the left ureter as they can be tethered by the medial pressure exerted on the mesentery. In case of difficulty, it is useful to combine with a medial posterior approach. Identification of the ureter with a ureteral catheter (luminous bougie or not) does not seem necessary to us.