Dissection Approaches

Fig. 6.1

‘Glove-port’ access device formed by use of conventional wound retractor, size 6 glove with three fingertips cut off and standard laparoscopic ports secured with non-absorbable suture ties

Position, Anatomy and Body Habitus

The majority of commercially available access devices have no more than five ports, and it is often the case that the assistant will be unable to retract effectively for the operating surgeon due to ergonomics or limitations of the access device. Consequently, the surgeon has to use gravity as their ‘third hand’, which may necessitate more severe patient positioning than usual, with steep head-down/head-up and lateral tilt. As such, the patient may need to be more securely strapped to the table with shoulder and side supports, rather than the isolated use of a gel mat. The preferred patient position for specific points of colorectal mobilisation will be discussed later.

There are a number of anatomical considerations that may limit the progress of a single-port case. The most obvious is the presence of adhesions from prior surgery. Adhesions may be managed more easily by SILS as compared with multiport laparoscopy. The SILS port is placed by mini-laparotomy at which point ‘open’ adhesiolysis can be performed. This permits the creation of a working space more quickly and readily identifies whether laparotomy will be necessary or not. Generally, all colonic resections that are suitable for laparoscopy can be undertaken by SILS, assuming they are performed by an appropriately trained surgeon. The same, however, is not true for rectal dissection. In particular, a significantly raised sacral promontory may prevent rectal mobilisation due to straight instruments rocking on the promontory, a problem that will not easily be overcome even when curved or angled instruments are employed.

Patient habitus is an obvious problem that affects all laparoscopic procedures . When beginning a SILS practice, it is wise to only embark upon this technique if one anticipates a case could be completed relatively easily if it were performed by conventional laparoscopy. When the surgeon becomes more confident and attempts all laparoscopic procedures using SILS, it can be a surprise how infrequently additional ports are required. While the author has on occasion successfully completed SILS left colon or sigmoid resections for patients with a BMI > 50 patient, safety is paramount. This should never be compromised for the sake of placing extra laparoscopic ports or conversion to laparotomy.

Medial Versus Lateral Approach

While there are many ways to safely perform SILS colonic mobilisation, the author’s preferred approach is lateral-to-medial dissection . The benefits this offers the surgeon are replication of open surgery with views of the ‘normal’ operative planes; minimal requirement to layer the small bowel out of the surgical field, which can be challenging with SILS procedures in obese patients; little to no input required from the assistant, who is likely to lack experience with SILS ergonomics or camera holding; and simpler retraction and better operative views due to the lack of dissection between mesocolic and retroperitoneal attachments. Nevertheless, a medial-to-lateral approach is popular in the USA, the UK and Europe. For the purposes of this chapter, both lateral-to-medial and medial-to-lateral dissection techniques will be discussed, and as in the real world, a mixture of these approaches is often necessary to complete technically challenging SILS procedures.

Mobilizing the Right Colon

Lateral Approach

The operating table is placed in the head-down position with a left lateral tilt, and the surgeon stands at the left side of the patient. A lateral-to-medial dissection is commenced by retracting the appendix into the left upper quadrant with the left hand and using a combination of energy device dissection and gently sweeping from lateral to medial to free the colon, caecum and terminal ileum from their parietal attachments (Fig. 6.2). As a surgeon becomes more confident, he/she will find scissor dissection leads to more accurate separation of surgical planes. Only the lateral aspect of the duodenum is exposed and mobilised from the right colon at this point. Thereafter, the dissection is continued to the corner of the parietal peritoneum where the hepatic flexure is encountered.

Fig. 6.2

Lateral-to-medial dissection of the caecum from the parietal peritoneum with an ultrasonic dissection device

The patient is then placed in the head-up position and continued left lateral tilt, with the appendices epiploicae of the proximal transverse colon grasped close to the bowel by the left hand of the surgeon. The colon is then deflected downward in the direction of the right iliac fossa. An energy device is used to free the supracolic-parietal attachments of the proximal transverse colon and hepatic flexure to meet the previously developed plane. The use of diathermy scissors is discouraged at this point due to the relatively large vessels that will be encountered in this area. When the peritoneal attachments have been released, progressive retraction of the right colon towards the left iliac fossa is undertaken. This allows a plane to be developed between the retroperitoneal structures and the colon, over the anterior surface of the duodenum, by a combination of gentle sweeping movements and diathermy scissors dissection until the colon is fully mobilised.

Medial Approach

The patient is positioned in the same way as described above. The small bowel is placed in the left upper quadrant, and the ileocolic pedicle is identified following suspension of the ileocolic fat pad or meso-appendix by the left hand of the surgeon towards the abdominal wall. An energy device is then used in the surgeon’s right hand to open the peritoneum underneath but parallel to the ileocolic vessels, up to the level of the superior mesenteric vein. After this is performed, the embryonic surgical plane can be seen and developed by blunt dissection towards the hepatic flexure. This plane is anterior to the duodenum, and this structure must be freed from the mesocolic fat prior to vessel division, or inadvertent duodenal injuries may occur (Fig. 6.3). The duodenum is best freed by downward blunt dissection. The lateral dissection under the colon is continued in a blunt manner in the same embryonic plane, as this will allow the operating surgeon to remain immediately above Toldt’s fascia and thus protect the ureter. The remaining lateral attachments of the colon and the terminal ileum are released as previously discussed.

Fig. 6.3

Medial-to-lateral dissection of the right colon . Supra-duodenal tunnel created to mobilise the ileocolic vessels, which are suspended over the laparoscopic retractors. The duodenum can be seen within the tunnel on the right

Mobilization of the Sigmoid Colon, Left Colon and Splenic Flexure

Lateral Approach

For this portion of the procedure, the operating room table is placed in the head-down position with right lateral tilt, and the surgeon stands on the right side of the patient. It is often easiest to free the sigmoid initially by utilising diathermy scissors rather than use an energy device, first by releasing any peritoneal attachments caused by diverticular disease or that are congenital in nature, before mobilising the sigmoid colon from Toldt’s fascia, leaving the white line with the patient (Fig. 6.4). The surgeon’s left hand should retract the colon towards the right side of the abdomen by sequentially holding appendices epiploicae along the colon while the right hand performs the dissection. The use of diathermy scissors is more precise and avoids any fusing of the embryonic planes that can occur with the use of energy devices. The ureter will be exposed during this dissection at the pelvic brim and easily identified during careful dissection, as is the case in open surgery. This mesocolic plane is then continued in order to mobilise the left colon until the point immediately distal to the splenic flexure.