Magnetic 3-D imaging colonoscopy

Examples of common and uncommon sigmoid loops seen during colonoscopy (AP views). (A) Intubation to the mid-descending colon with a sigmoid 'N' spiral loop. (B) Sigmoid alpha loop with endoscope inserted to splenic flexure. (C) (Atypical) Reverse alpha loop with endoscope tip in descending colon. (D) Atypical counter-clockwise (reverse sigmoid) spiral loop with the endoscope tip in the proximal sigmoid colon. (E) Complex sigmoid spiral loop with endoscope inserted to the proximal sigmoid colon.