Colon Cancer
Colectomy for Cancer
|
|
||||||||||||||
Technique
Technique - Left Colectomy
Anatomy
Guidelines
A few guidelines should be followed when one performs laparoscopic colon resection.
- 1. One must use stable trocars, hereby reducing local parietal trauma.
- 2. The tumour itself should not be mobilized but rather a no-touch technique should be used.
- 3. Vascular control should be achieved at the beginning of the procedure.
- 4. Tumour exclusion plus bowel lumen occlusion proximally as well as distally should be performed.
- 5. The extraction site through which the sample is withdrawn should be protected
- 6. The resection should be no smaller than with the conventional approach
- 7. Preoperative lavage should be avoided as much as possible so as not to scatter tumour cells.
Laparoscopic colon resection is a complex endeavour since it involves wide dissection, causing frequent tool and camera changes.
Preparation of the patient
Bowel preparation is essential; not only for obtaining a clean colon but also for avoiding dilated small bowel. The patient should be put on a residue-poor diet for 8 days, 48 hours before the procedure 3 litres of poly-ethilen glycol should be ingested. An additional 1 or 2 litres of poly-ethilen glycol should be drunk the day before the procedure. With this regimen colon preparation should be satisfactory and the small bowel should not be dilated.
Placement of the patient
The patient is in a so-called lithotomy position, the arms along the body. A nasogastric tube and an indwelling Foley-catheter are in place, the surgeon and the first assistant are located to the right of the patient, the scrub nurse is placed between the legs of the patient. The video monitor is right in front of the surgeon, at the level of the patient's left thigh, so that surgeon, optical system, operative field and monitor are approximately on the same axis. Scissors, the aspiration cannula and the clip applier are placed in a pocket, which is fixed on the patient's right thigh.
Placement of trocars and surgical tools
4 trocars are used for this procedure. The first 10-mm trocar is placed 1 cm cephalad of the umbilicus and will harbour the optical system. A second 5 mm trocar is inserted in the right lower quadrant on the midclavicular line. This trocar opening can be enlarged if needed so as to allow the introduction of a linear cutting and stapling devices. A third 5 mm trocar is placed on the right midclavicular line at the level of the umbilicus. A fourth 5 mm trocar is placed in the left upper quadrant approximately at the level of the umbilicus on the left midclavicular line, An additional 5 mm trocar can be placed in a suprapubic position, if one wants to perform stapling and extraction from this side. The second trocar allows the introduction of scissors or of a coagulating hook, held in the surgeon's right hand. The third trocar harbours the grasping forceps, that will be kept in the surgeon's left hand. The fourth trocar in the left upper quadrant will harbour an atraumatic grasper.
Exploration of the abdominal cavity
If one expects problems with localizing the tumour a preoperative colonoscopy can be performed. However it's preferable to have the gastro-enterologist mark the tumour preoperatively with methylene blue or with China ink. The problem with peroperative colonoscopy is that air insufflation; necessary for visualisation with the colonoscope will reduce the space of vision for the surgeon.
Once the surgeon has spotted the tumour site, the entire abdominal cavity is checked so as to rule out metastatic disease.
Exposure of the left colon
The patient is put in a 10_ Trendelenburg position with a 20' roll to the right. The surgeon stays to the right of the patient or places himself between the legs. The larger omentum is reflected on the anterior side of the stomach and tucked in front of the left liver lobe, hereby exposing the transverse colon. The Trendelenburg tilt is then increased up to a 30_. The small bowel loops are pulled cephalad and tucked in a supramesocolic position so that the entire mesocolon, the third duodenum and Treitz' angle are clearly visible. Sometimes it is necessary to maintain the small bowel in the supramesocolic position by using a grasper from trocar 4. This grasper snaps the small bowel about 20 cm distal to the angle of Treitz and creates a hinge that maintains the small bowel in its desired position.
Exposure of the pelvis necessitates clearance of terminal ileum and caecum. If necessary an additional grasper can be placed through a fifth trocar placed on the right midclavicular line about 8-10 cm proximal to the third trocar. This grasper picks up the distal ileum about 30 cm proximal to the ileocaecal valve and will keep the last small bowel loops as well as the caecum in the right lower quadrant in an orthostatic fashion.
In female patients exposure of the pelvis can be favourably influenced by retracting the uterus with percutaneously inserted transuterine stitch.
It's impossible to expose the entire left colon from midtransversum down to the upper part of the rectum at the same time. The procedure has to be subdivided in 2 steps, first dissection of the splenic angle and then dissection of left colon and rectosigmoid.
Strategy of left colectomy
The strategy of left colectomy is identical in case of cancer or benign colitis. First Toldt's fascia must be dissected, together with the perirectal fascia. Second the left paracolic gutter must he severed. Third Douglas' pouch must be incised. Fourth the mesorectum and distal rectum must be transsected and fifth the proximal colon must be transsected as well. In order to separate colon and mesocolon from the retroperitoneum one must incise the parietal peritoneum along the aorta, dissect lower mesenteric artery and lower mesenteric vein and finally sever the neural branches coming from the periaortic plexus which innervate the mesocolon.
Incision of the mesocolic peritoneal sheet
The peritoneal sheet at the root of the left mesocolon is grasped by the forceps and is incised with scissors from distal to proximal, starting at the sacral promontory, and continuing along the aorta up to the third part of the duodenum. The incision is then taken to the patient's left, aiming towards the splenic angle, hereby crossing the path of the inferior mesenteric vein, on its way to the lower border of the pancreas.
Ligation of inferomesenteric artery and vein
The grasper in the left lower quadrant's trocar grasps the mesosigmoid, which is pulled cephalad towards the patient's left. This manoeuvre puts the inferior mesenteric artery under traction. The root of this artery is then clearly visible at approximately 1-3 cm distal to the third part of the duodenum. The grasper is then repositioned so as to pick up the peritoneum exactly at the level of this artery.
If one decides not to mobilize the splenic angle, the artery is severed just distal to the origin of the left colic artery.
When the patient is obese a significant dissection is needed to reveal the artery. The dissection is performed with the coagulating hook. The periarterial neural plexus should be left posteriorly, away from the specimen. The periarterial lymph nodes however should be included in the specimen. A needle holder is introduced in the second trocar, looped around the artery and the artery is tied with intracorporeal knotting technique. Additional clips can be placed for safety.
The inferior mesenteric vein is clipped at the lower border of the pancreas.
Separation of Toldt's fascia
Unlike with open surgery, the incision of the left colic gutter is delayed until later in the procedure. The purpose of this delay is to avoid that the left colon would drop medially and obscure the operative field. Moreover, the surgeon being positioned to the patient’s right very logically wants to keep the dissection of the most remote part of the operative field towards the end of the dissection.
The correct technique to separate the fascia of Toldt (the adherent left mesocolon) is to grasp the distal part of the inferior mesenteric artery, which is lifted anteriorly. This is done by the surgeon's left hand, while his right hand is dissecting very carefully with the tip of the scissors in the direction pointing towards the patient's left shoulder. The right plane of dissection is the one that leaves anteriorly only the anterior peritoneal sheet, the veins, the arteries and the nerves. Automatically the left ureter and the fascia of Gerota will be left posteriorly. The general shape of the dissection is a pyramid with the forceps from the fourth trocar at the apex.
The superior limit of dissection is the inferior border of the pancreas. The left limit is the left paracolic gutter. The next step of the dissection is oriented distally. Small branches from the neural plexus going towards the left colon and the sigmoid must
be severed at this stage.
Dissection of the pararectal fascia
Dissection of the pararectal fascia is initiated at the level of the sacral promontory. The right plane of dissection is in a continuous plane with the one of Toldt's fascia. The most obvious danger is to start dissecting too posteriorly into the presacral space, which would expose the presacral veins which are easily torn. When one enters the right space however dissection is bloodless. The space located between the visceral sheet of the peritoneum and the parietal sheet is located anterior to the left and right hypogastric nerves, which must be seen and parietalised during the dissection.
Incision of the left colic gutter
The forceps in the fourth trocar pulls the sigmoid loop towards the right upper quadrant. The peritoneal reflexion is held with the forceps in the third trocar. This provides counter-traction which facilitates dissection with scissors coming from the second trocar. Incision is continued from distal to proximal i.e. from the iliac vessels at the level of the sacral promontory all the way up to the splenic angle. This incision joins the previously dissected posterior mesocolon. Subsequently incision is oriented distally towards the left side of the rectum. The ureter is again visualised and left posteriorly. Dissection finally joins the perirectal fascia located at the left side of the rectum.
Incision of Douglas' pouch
The grasper in four pulls the upper rectum to the left of the patient. The grasper in three grasps the peritoneal sheet overlying the bladder and pulls it anteriorly. The peritoneal reflexion is severed from right to left. The prerectal space located between colon and Denonvilliers' fascia is opened and the anterior side of the rectum is exposed.
Dissection of the mesorectum
At the chosen level for transsection the muscular layer of the rectum is exposed on its entire circumference. The dissection can be performed either with scissors, with coagulating hook or with an ultrasonic scalpel. The superior hemorroidal vessels are coagulated or clipped.
Transsection of rectum
The second trocar located at the superior and anterior iliac spine is replaced by a 12 mm trocar, which allows introduction of the linear cutting and stapling device. Alternatively this device can also be introduced in a suprapubic position if the stapler is flexible. It is essential that the stapling device be perpendicular to the rectum. If this is not the case, transsection of rectum is very difficult.
Freeing of the splenic angle, laparoscopic anatomy of the splenic angle
Freeing of the splenic angle allows one to obtain more slack with the proximal colon, which guarantees a tension free anastomosis. Freeing of that angle can be performed either by simple severance of the peritoneal attachments of the colon at that level or by additionally cutting the root of the left mesocolon, care being taken to spare the midcolic artery. Direction of dissection can be either from medial to lateral or the opposite.
Freeing of the splenic angle from medial to lateral
The posterior attachments of the colon at the splenic level are severed after opening Toldt’s fascia as previously described. Posterior dissection is performed from medial to lateral while the surgeon is holding the root of the left mesocolon in a ventral direction while Gerota's fascia and the anterior side of the pancreas are left posteriorly. It is essential not to dissect in too posterior a direction so as not to injure the pancreas or indeed to open the retropancreatic space.
Toldt's fascia dissection is continued along the lower border of the pancreas up to the splenic angle and the left paracolic gutter. The bursa can be opened at this level by severance of the anterior layer of the transverse mesocolon. In order to continue the dissection surgeon and patient must be put in a different position: the patient is put in reversed Trendelenburg. The lateral roll is maintained. The surgeon now is placed between the patient's legs. Dissection of the greater omentum is initiated at the left side of the transverse colon, a little lateral of the midline and is continued towards the splenic angle. The bursa must be opened at this stage in order to allow good visualisation of the blood vessels in the transverse mesocolon, which must be preserved. This step of the dissection is straight forward, good traction and counter-traction being obtained by ventral traction of the omentum and posterior traction of the transverse colon.
Mobilisation of the splenic angle from lateral to medial
The patient is placed in slight reversed Trendelenburg with 20 degrees lateral roll. The surgeonpositions himself betwen the patient’s legs. The surgeon’s right hand is holding the scissors introduced in 4 (Ci-4), while his left hand grasper, introduced in 2 (PAT-2) is pulling the colon distally and to the right.
If one wants to simply mobilise the splenic angle in view of a limited resection, like for a benign polyp, the colo-omental attachments are first best severed from right to left (from mid-transversum towards the splenic angle). Subsequently the left gutter, the phrenocolic ligament (from proximal to distal) and finally the left mesocolonic posterior attachments are severed while the surgeon pulls the colon towards the right lower quadrant with the (PAT-2) grasper.
Transsection of the left mesocolon.
The left mesocolon is incised at the chosen level. The Drummond arcade is spared. Even though some surgeons only transsect the mesocolon while exteriorising the specimen, our technique avoids cumbersome hematoma’s created by forceful pulling while exteriorising. The transsected mesocolon also gives additional slack. The proximal colon section is prepared for anastomosis outside the peritoneal cavity.
Extraction and resection of the tumor
The specimen is to be extracted through a mini-laparotomy obtained by enlarging a trocar opening in the right lower quadrant or suprapubically. It is extremely important to protect the wound by a plastic sleeve in order to avoid soiling by tumor cells or fecal material. The proximal transection level of the colon is dissected free of all fat and small vessels. The bowel is then transected and removed.
The anvil of a circular stapler is introduced in the bowel lumen and a purse string performed. The bowel is replaced intraperitoneally and the mini laparotomy is closed in layers.
Anastomosis
The circular stapler is introduced transanally and a conventional circular stapled anastomosis is performed through the distal staple line. The resected doughnuts are checked for completeness. Anastomosis must be free of traction and well vascularised. The anastomosis can be tested for air leaks after its immersion under saline.
