Withdrawing the Endoscope and Blind Spots

Compared with advancing the scope, withdrawal after reaching the terminal ileum does not pose any technical difficulties. Close inspection of the colon is made on withdrawal, as is the collection of pathological samples and the performance of any necessary diagnostic or therapeutic interventions (biopsy, poly-pectomy, etc.). Slowly withdrawing the instrument and per-

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Distal Sigmoid Polyp

Fig. 5.32 Polyp in the proximal rectum. a After endoscopic resection, a small remaining polyp piece was visible from distal next to the ulcerated resection site. Another polyp piece is likely on the other side of the fold at the lower edge of the resection site. b The whole polyp could only be seen by viewing (retroflexion) behind the fold. Retroflexion was performed using a gastroscope, which offers more flexibility.

Fig. 5.33 Retroflexion in the rectum: at the top right, the endoscope shaft can be seen as it comes through the anal canal. The squamous epithelium lining the anal canal can be seen circumferentially around the endoscope; the transition to the columnar epithelium of the rectal mucosa is clearly visible. A secondary finding is a small hyper-trophied anal papilla directly next to the endoscope (at about the 12-o'clock position).

Fig. 5.32 Polyp in the proximal rectum. a After endoscopic resection, a small remaining polyp piece was visible from distal next to the ulcerated resection site. Another polyp piece is likely on the other side of the fold at the lower edge of the resection site. b The whole polyp could only be seen by viewing (retroflexion) behind the fold. Retroflexion was performed using a gastroscope, which offers more flexibility.

forming a circumferential inspection of the intestinal wall in all colon segments avoids missing smaller pathologies. While the inspection of surfaces of the folds turned toward the anus is usually unproblematic, proximal surfaces (toward the cecum) can be difficult to examine. Sufficient examination of these areas requires slow withdrawal of the endoscope and the use of adequate air insufflation. Figure 5.32 shows a large piece of a polyp behind a fold in the proximal rectum. Despite its size, it could only be detected by slow withdrawal and careful inspection.

"Blind spots." In addition to mucosal areas throughout the colon proximal to the folds, there are also specific colon segments that should receive special attention because of their anatomical configuration. Thorough inspection of these so-called blind spots can sometimes be difficult, but is nevertheless absolutely vital. The area in the cecum underneath the ileocecal valve and the inner sides of both colon flexures can be obscured or difficult to view (see also Figs. 5.16, 5.19). Repeatedly passing the colono-scope may be necessary especially for sufficient circumferential assessment of the flexures. Additionally, administering an antispasmodic drug (e.g., Buscopan) can be helpful. Similar problems can occur in sharp curves of the winding sigmoid colon and in the rectosigmoid junction (see Fig. 5.8). A study by Rex et al. illustrates the problem: when colonoscopy was repeated the same day, adenomas were detected in 24% of patients where they had previously been "missed." While the majority of these were small adenomas (< 6 mm), 6% were larger than 1 cm (6). The inspection of each colon segment can only be completed when the examiner is certain that all mucosal sections have been sufficiently viewed. Withdrawal of the endoscope is the simpler part of the examination, doing so slowly and carefully is the deciding factor in the examination, diagnosis, and the overall quality of the ileocolonoscopy.

Fig. 5.33 Retroflexion in the rectum: at the top right, the endoscope shaft can be seen as it comes through the anal canal. The squamous epithelium lining the anal canal can be seen circumferentially around the endoscope; the transition to the columnar epithelium of the rectal mucosa is clearly visible. A secondary finding is a small hyper-trophied anal papilla directly next to the endoscope (at about the 12-o'clock position).

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Constipation Prescription

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