The basic insertion technique for the distal small intestine is to advance the endoscope tip with minimum insertion force so the endoscope forms large concentric circles (which are formed by stretching the mesentery in a fan shape around the fixed part of the mesentery on the retroperitoneum) (Figs. 8.5, 8.6). As described above, the operator should avoid forcible insertion of a sharply angled endoscope. Reducing the angle as much as possible and swinging the tip allows effective insertion. The small intestine is freely mobile, and its bends are not fixed unless there are adhesions. It is therefore unnecessary to intricately bend the endoscope to follow the bends ahead. Small turns are negotiable by changing the direction of the endoscope tip and using the slalom technique. After the endoscope is inserted until its proximal end reaches the rear end of the overtube, the balloon at the endoscope tip is inflated to secure the endoscope tip at this position, the overtube balloon is deflated, and the overtube is inserted along the endoscope. After the rear end of the overtube reaches the 155-cm marking on the endoscope, the overtube balloon is inflated so both balloons can grip the intestine. With both balloons inflated, the endoscope is withdrawn together with the overtube to pleat the intestine over the overtube and to shorten it.
During the procedures the operator may use fluoroscopic images to ensure that the entire endoscope forms concentric circles (continuous fluoroscopic monitoring is not necessary for experienced operators) and endoscopic views to ensure that the balloons are in position. The small intestine is freely mobile in the abdominal cavity. When the endoscope seemingly slips on a fluoroscopic image but not on an endoscopic view, the endoscope is actually in position, and the small intestine is changing position instead. This manipulation reduces looping without the endoscope tip slipping, and it gathers and shortens the inserted intestine on the overtube. The manipulation not only shortens the intestine to make the best use of the working length of the endoscope, it also straightens the intestine ahead and reduces
bends, thereby facilitating insertion. Once the intestine adopts a shape that facilitates effective insertion, the endoscope tip can be advanced by repeating the endoscope insertion and shortening of the small intestine, with the shape maintained. The endoscope tip is actually advancing even when it seemingly moves back and forth on a fluoroscopic monitor.
When a sharp bend makes insertion difficult, the overtube is advanced to the bend instead of trying forcible insertion. Both balloons are then inflated to grip the intestine, and the endoscope is withdrawn together with the overtube to reduce the bend, which facilitates insertion. In short, double-balloon endoscopy makes use of the mobility of the small intestine and allows insertion while modifying the shape of the intestine for easy insertion. This should be kept in mind to achieve efficient insertion.
When inserted through the mouth, the endoscope may be advanced clockwise or counterclockwise to the patient so long as it allows smooth insertion (Fig. 8.5). When inserted through the anus, the endoscope should be inserted to ensure that it forms concentric circles counterclockwise (Fig. 8.6). Concentric insertion facilitates shortening of the small intestine and allows good maneuverability of the endoscope tip.
Nonconcentric insertion may be addressed by withdrawing the endoscope and overtube with the balloons inflated as much as possible before slipping or adjusting the direction of the endoscope tip under fluoroscopic guidance. For insertion through the anus, the ileum adjacent to the ileocecal region may be positioned deep in the pelvic cavity, precluding concentric insertion. In this case, fluoroscopy is used to drag out the ileum lying deep down to ensure concentric insertion. The small intestine is freely mobile unless there is an adhesion in the abdominal cavity, and it is therefore possible to adjust the shape and position of the small intestine to facilitate endoscope insertion. The concentric shape is favorable for physiological movement of intestinal contents, and repositioning the small intestine has caused no problem in patients.
After deep insertion into the small intestine and inflation of the balloon at the endoscope tip, further insertion of the overtube may be impossible because most of the overtube is inserted in the body with a minimal part on the outside (Fig. 8.7). At this stage, the balloon at the endoscope tip is inflated, and the overtube is withdrawn together with the endoscope before the overtube balloon is deflated. After the endoscope is withdrawn until the 155-cm marking comes out of the body, the overtube balloon is deflated, and the overtube is inserted along the endoscope (Fig. 8.8A). If only the endoscope is withdrawn and the overtube is not pulled back, subsequent insertion will be less effective. Withdrawal of the endoscope alone shortens the intestine between the two balloons on the endoscope. The shortened intestine remains between the two balloons after the overtube is advanced and its balloon is inflated. When the balloon at the endoscope tip is deflated, the shortened intestine instantly stretches beyond the endoscope tip, precluding effective insertion (Fig. 8.8B).
The endoscope tip in the distal small intestine is most likely to slip when the small intestine is shortened with both balloons inflated and the balloon at the endoscope tip is deflated. The operator should be alert and ready to advance the endoscope when deflating the balloon at the endoscope tip in the distal small intestine.
When endoscope insertion is difficult and reaches a deadlock, the posture of the patient can be changed. This may break the deadlock because a change in the influence of gravity may alter the positional relation between the intestine and the endoscope in the abdominal cavity and the distribution of intestinal contents.
Although the double-balloon method allows total enteroscopy, insertion efficiency decreases in the distal small intestine because the length of advancement for each balloon manipulation is shorter as the endoscope is advanced more deeply. Insertion via the mouth into the ileocecal region is possible under favorable conditions. However, it is more efficient to perform two examinations: one through the mouth and the other through the anus. When two examinations are performed, a tattoo is placed at the deepest reachable point, which is used as a mark during the subsequent examination from the opposite direction. Whether the endoscope is to be inserted through the mouth or the anus during the initial examination is carefully determined on the basis of the patient's medical history and the
results of the preoperative examination; however, a lack of information for decision making is not uncommon. When total enteroscopy is indicated, we preferentially insert the endoscope through the anus because this method causes less discomfort to the patient. We observe the widest possible area by anal insertion, thereby reducing the time of observation required with the oral insertion. Unless an emergency dictates otherwise, examination from the opposite direction is preferably performed on some other day because of concerns about residual air entering the intestinal tract during endoscopic observation.
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