Colon anatomy based on CT colonography and fluoroscopy: Impact on looping, straightening, and ancillary maneuvers in colonoscopy

Aims: Unsedated colonoscopy is an uncomfortable procedure for most patients. Discomfort during colonoscopy is largely related to looping of the colonoscope, which displaces the colon from its native configuration and stretches attachments to the mesentery. Therefore, complete intubation of the colon is considerably difficult in up to 10–20% of procedure. Reasons for failure of complete colonocopy are multifactorial. Aims of this study were (1) to determine the „normal“ colon anatomy in CT-colonoscopy with special focus on length, number of flexures and tortuosity and (2) to assess frequency and type of looping as well as straightening maneuvers based on fluoroscopic findings.

Methods: 100 consecutive screening patients underwent CT colonography and another 100 cases traditional colonoscopy with fluoroscopic aid. Interactive 3D colon maps and 2D MPR imgages from virtual procedures were indepently reviewed by two experienced GI radiologists and GI endoscopists. Colonoscopy was performed by three board-certified gastroenterologists. Fluoroscopic films of each case were recorded and retrospectively analyzed.

Results: There was a considerable difference in overall colonic length between CT colonography and conventional colonoscopy (167cm vs. 93.5cm). Number of acute angle flexures and degree of tortuosity was higher in CT colonography than previously assumed. The cecum was reached in 98/100 cases with conventional colonoscopy. Procedures were incomplete due to a obstructing sigmoid cancer and a floppy redundant colon in another case. Looping occurred in 73/100 cases and straightening maneuvers with fluoroscopy were highly effective in 95%. Looping was more common in older and smaller women.

Conclusions: Predictive anatomical factors for potentially difficult endoscopic colonoscopy can be defined by CT colonography. Looping occurs frequently during routine colonoscopy but hindered cecal intubation in only one case. Short-term fluoroscopy is extremely helpful to guide straightening and ancillary maneuvers and should be used selectively in patients with looping during conventional colonoscopy.