In general, we place four to five cannulae for most colorectal procedures: one for the laparoscopic camera, two for the operating surgeon, and one or two for the assistant surgeon. This technique provides best surgical flexibility in all four quadrants, allowing operating and assistant surgeons to cooperate. In most instances, the operating surgeon will place the cannula opposite to the site of the pathology, which allows the greatest room to work and to visualize the pathology site. Because any abdominal wall cannula will restrict the mobility of the laparoscopic instruments, the cannula locations should also be chosen to allow the greatest mobility possible, given several additional considerations: each cannula should be placed with a distance of at least 8 cm to prevent the instruments from "sword-fighting" each other. In addition, cannulae should also be placed 6-8 cm away from the lapa-roscope site because closer placement impedes a clear overview of the laparoscope.
After pneumoperitoneum is established with the Veress needle, the umbilical incision is usually used for the first cannula insertion. Any kind of access systems can be used, but our current preference is an endoscopic threaded imaging port system (EndoTIP™; Karl Storz, Tuttlingen, Germany) that can be introduced under optical control. Unlike conventional trocars, the EndoTIP™ requires no trocar and minimal axial penetration force during insertion. The device has a proximal valve section and a distal cannula section with a single thread winding around its outer surface, ending in a blunt tip (Figure 6.4). The tip does not cut tissue, but is inserted by rotation, displacing structures while minimizing the risk of accidental injury. The EndoTIP™ system can be categorized into so-called "optical access" systems, and seems safely applicable for obese patients with thick abdominal wall, where a standard "open" technique is technically difficult. Ternamian and Deital2 used the EndoTIP™ system in 234 consecutive patients including moderately and markedly obese patients, and reported that the system can be safely used for any body weight patients. Although the use of EndoTIP™ or other similar systems may minimize the risk of injuries during the first cannula insertion, the area just below the initial entry site should be inspected laparoscopically to detect possible visceral injury from the blind entry of the Veress needle.
Usually, the secondary cannulae are placed under laparoscopic guidance to avoid puncturing significant intraabdominal or retroperitoneal structures. Before insertion, the abdominal wall should be transillumi-nated to identify any major vessels at potential entry sites so these vessels can be avoided. The size of the skin incision for each cannula must be planned carefully. If the incision is too small, friction will develop between the skin and the cannula sleeve; consequently, greater force will be required for insertion, which will increase the risk of uncontrolled insertion and inadvertent injuries of underlying viscera. However, if the incision is too large, insufflated gas may leak out
around the incision during the procedure and the cannula may dislocate more easily. It is wise to make the incision slightly too large than too small - risking an intraabdominal injury merely to save 2-3 mm of the abdominal incision is senseless and possibly dangerous.
The frequent slipping of the working cannula from the abdominal wall while instruments are moved in and out can cause much frustration. Once the port is out, pneumoperitoneum is lost, and the whole process must be reestablished to regain a view. This is time-consuming and potentially catastrophic when the forceps is holding an important structure or when profuse bleeding is encountered. In the case of frequent cannula dislocation, commercially available "port grippers" are used (Figure 6.5). These grippers can effectively stabilize the cannulae in the abdominal wall by a screw design; however, they usually require slightly larger skin incision for best results. Forcibly applying the grippers in the incision may damage the tissue and thus impair wound healing. An alternative is a single throw of a fixation suture (Figure 6.6).3 A strong 0 suture is placed through-and-through the skin around the cannula entry site. The sleeve is pulled back until just enough
length is inside the peritoneal cavity to maintain pneumoperitoneum. The suture is secured to the cannula by wrapping it around the insufflation port. The cannula can be pushed inside the abdomen but cannot be pulled out because of the holding suture. The surgeon can easily adjust the length of the port inside the abdomen with one hand.
To further stabilize the cannula, we use the following technique: A tube with adequate length is sliced longitudinally and wrapped on the cannula. The length of the tube should be preadjusted so that the sleeve may be placed in the abdominal cavity with an adequate length. An abdominal U-stitch is then placed through the tube, fixing the cannula in the abdominal wall. Another suture is placed on the distal part of the tube to firmly secure the tube on the cannula (Figure 6.7).
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