BACKGROUND
Adult colonic intussusceptions are relatively rare and are mostly caused by organic structures that serve as lead points. However, the pathogenesis of adult intussusception is not fully understood, and no cases of retrograde colonic intussusception without pathological abnormalities or associations with colonoscopy have been reported.
CASE REPORT
A 74-year-old woman presented with abdominal distension and constipation. Abdominal computed tomography (CT) revealed marked dilatation of the right and sigmoid colon, initially suggesting volvulus of the sigmoid colon. Observation of the left colon revealed no abnormal findings on the colonoscopy. Due to the persistence of abdominal symptoms from right colon dilatation, another colonoscopy was performed, and a transanal drainage tube was inserted into the transverse colon. Enterography showed a steep contrast interruption in the descending colon, which was missed at this time. The patient’s abdominal pain worsened 3 days after removal of the drainage tube. Retrograde intussusception of the sigmoid colon was discovered on abdominal CT, and a laparoscopic left hemicolectomy was performed. Pathological examination revealed multiple ulcers in the superimposed area, but no abnormal organic findings that could be considered as a lead point were found. In this case, the stretching technique and/or shear stress on the sigmoid colon by a second colonoscopy may have contributed to the development of this condition.
CONCLUSIONS
This is the first report of colonoscopy-associated retrograde colonic intussusception without organic abnormalities. Although much is unknown about the pathogenesis in this case, it may provide new insights into the pathogenesis of intussusception.

Keywords: Colonoscopy; Intussusception; Laparoscopy; Colon