Descending Colon

Sigmoid Flexure
Fig. 5.13 Variations of the splenic flexure with different angles between the descending colon and transverse colon. a A "high" flexure, ca. 180°. b "Drooping flexure."
Splenic Flexure Transverse Colon

creating an angle of 180° (Fig. 5.13). Passage can be especially difficult if the splenic flexure is displaced vertically. In such cases, "pushing up" the endoscope in the more distal colon (especially the sigmoid colon) followed by withdrawing the instrument can advance the endoscope in the left side of the transverse colon. This is basically the same procedure as the alpha maneuver described above, though instead of forming a complete loop in the sigmoid colon, merely the beginning of a bend or an incomplete loop (combined with external pressure if necessary) is sufficient (cf. Fig. 5.9 b, Fig. 5.10).

Transverse colon. Recognizing that the transverse colon has been reached is usually simple, given its typical triangular-shaped lumen and strong, evenly spaced haustrations (Fig. 5.14). Compared with the relatively uniform, straight path of the descending colon, the position of the transverse colon is more variable due to its intraperitoneal position and fixation on a meso-

colon, which may vary in length. The fixation on both retroperi-toneal fixated colon flexures causes it to bend convexly and ven-trally. The middle of the transverse colon, however, droops caudally. The path between splenic and hepatic flexures can vary greatly; at the one extreme, the transverse colon can be nearly horizontal, while at the other it can "droop" all the way down to the minor pelvis (Fig. 5.15). This results in any number of related difficulties in passage and therefore also advancing the endoscope in the hepatic flexure.

External pressure can lift a drooping midtransverse colon cranially and enable the advancement of the endoscope to continue (see below). It is also possible to push the endoscope "up" after reaching the most caudal point in the drooping transverse colon. If the instrument is then carefully withdrawn, a cranial displacement of the midtransverse colon and corresponding straightening of the transverse colon can ease passage and retrieve "used-up" endoscope length. Passage of the transverse

Proximal Colon colon and reaching the hepatic flexure is sometimes only possible using a combination of advancing/withdrawing and external hand pressure. Optimal cooperation between examiner and assistant is essential. Pronounced angling of the lumen toward the ascending colon is a sign that the endoscope is reaching the hepatic flexure (Fig. 5.16).

Hepatic flexure. The fixation of the hepatic flexure and the ascending colon to the posterior abdominal wall combined with the mobility of the intraperitoneally located transverse colon can result in sharp angling at the hepatic flexure. The situation is similar to the transition described above from the intraperi-toneally situated sigmoid colon to the retroperitoneally fixated descending colon; the difficulties passing the hepatic flexure are analogous. If at this point the patient is still in the left lateral position, it is strongly recommended that he should change position if problems passing the hepatic flexure are encountered; the patient should be supine or even in the right lateral position. In some cases, simply changing the position of the patient results in visualization of the previously displaced lumen of the ascending colon and can enable the examiner to overcome the flexure without a problem. If passage continues to be difficult, it is often necessary to push the endoscope up until the instrument tip is placed where the ascending colon begins. This part of colonoscopy often causes discomfort to the patient. As soon as the instrument tip is positioned in the ascending colon, it should be straightened by pulling back. This assists further advancement considerably and often the endoscope tip moves further toward the cecum as a result.

Applying external pressure can also be a significant help with the hepatic flexure. Splinting the sigmoid colon, a drooping transverse colon, or both can help straighten the endoscope, preventing repeated looping which "uses up" endoscope length while helping to reach the ascending colon successfully. If this does not work, additional external hand pressure on the right flank with the flat of the hand placed dorsally or slanted laterally to apply pressure directly to the flexure can be very helpful (see below).

Displaced Transverse Colon

Fig. 5.15 Schematic illustration of various paths of the transverse colon.

a "Drooping" transverse colon. b Nearly horizontal transverse colon.



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