Advancing the Endoscope in the Sigmoid Colon Sigmoidoscopy

Normal procedure. After reaching the rectosigmoid junction about ca. 16 cm proximal to the anocutaneous line, the endos-copy of the sigmoid colon begins. The sigmoid colon is situated intraperitoneally and is highly variable in length. The junction between rectum and sigmoid colon often appears as an acute bend in the lumen. The sigmoid colon can also be recognized by its prominent, circular folds. Passing the sigmoid colon with the patient lying in the left lateral position is unproblematic in simple cases where the sigmoid colon shortens itself, enabling easier passage through curves. Passing the sigmoid-descending junction is often more difficult in this position, especially for more slender patients, as the sigmoid colon is forced into the left abdomen, narrowing the angle of the junction with the descending colon. Changing position to the supine position—or, especially for slender patients, to the right lateral position—allows the sigmoid colon to fall more into the middle and right

Doublebarrel Colostomy
Fig. 5.7 Schematic illustration of various stomas. a: end colostomy, b: double-barreled colostomy, c: end ileostomy.

lower abdomen, thereby straightening the angle and making passage of the endoscope tip into the descending colon significantly easier.

Constant visualization of the lumen is desirable for passing the sigmoid colon. The instrument should be kept as straight as possible, without significant bowing or looping. However, individual differences in length and course of the sigmoid colon can make viewing the lumen more difficult and in some patients, looping cannot be avoided.

"Blind" advancement of the endoscope and changing patient position. If the view of the colonic lumen is obstructed or prevented by sharp angling, the examiner can attempt to ascertain luminal direction and briefly point the instrument tip without visualization in the presumed direction of the lumen, using gentle pressure to advance the endoscope in this direction. The presumed direction of the lumen is often indicated by shadowing (Fig. 5.8). Such maneuvers, which are performed only in exceptional cases, require experience, a light touch, and extreme concentration. The procedure must be stopped if macroscopic changes to the nearby mucosal surface (blanching, bloodless-

Sigmoidoscopy

Fig. 5.8a, b Acute angling of the lumen

(example shown: sigmoid-descending junction). The direction of the lumen cannot be seen either at about the 7-o'clock position (a) or at the 12-o'clock position (b), but it can be presumed, in part due to shadowing (arrows). In exceptional situations, the endoscope tip can be very carefully advanced in the presumed direction without visualization.

Fig. 5.8a, b Acute angling of the lumen

(example shown: sigmoid-descending junction). The direction of the lumen cannot be seen either at about the 7-o'clock position (a) or at the 12-o'clock position (b), but it can be presumed, in part due to shadowing (arrows). In exceptional situations, the endoscope tip can be very carefully advanced in the presumed direction without visualization.

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