|Home | About | Journals | Submit | Contact Us | Français|
Most retrograde intussusceptions occur in the sigmoid colon, perhaps initiated by antiperistalsis.
A woman aged 57 was seen twelve hours after the sudden onset of lower abdominal pain. The pain had become a constant ache in the left lower quadrant. She had been nauseated and constipated for a day but had been passing flatus. On examination she was mildly tender in the left iliac fossa, where a poorly defined mass was felt. Overnight, some distension of the abdomen developed. A plain abdominal film showed air-filled large bowel to the level of the splenic flexure and with little large bowel shadow distal to this. An ultrasound scan suggested the possibility of intussusception of the left colon but the presence of air filled loops of bowel precluded confident interpretation. A CT scan confirmed reverse intussusception of the sigmoid into the descending colon (Figures (Figures11 and and2).2). A Gastrograffin enema was thought unnecessary in view of this evidence. At laparotomy the sigmoid colon was found to be invaginating backwards to the level of the splenic flexure. The intussusception was partly reduced and a left hemicolectomy was performed with primary anastomosis. On opening of the resected colon, there was some necrosis and oedema of the bowel wall, with a sessile 2 cm × 2 cm × 1.5 cm polyp at the apex of the intussusceptum. Histological examination showed this to be a tubulovillous adenoma with moderate dysplasia.
In adults, intussusceptions account for up to 5% of cases of bowel obstruction, and 90% are secondary to a definable lesion. In children, by contrast, 80–90% are without an identifiable cause.1 Reviewing the published work from 1667 to 1955, Akehurst2 found 103 cases of retrograde intussusception, most of them combined with antegrade intussusception. There were 12 cases of uncombined retrograde intussusception of colon in adults.2 In a thorough search we could find reports of only 25 retrograde intussusceptions of the colon,3 most of which were in adults.
The mechanism of intussusception is not clear. One proposal is that the peristalsis and food push the lead point, with adjacent bowel, into the relaxed intestinal segment distal to it. Intussusception commonly occurs where freely moving segments of bowel become fixed, either by retroperitoneal location or by adhesions.1 Oedema of the affected bowel prevents spontaneous reduction while obstruction and vigorous peristalsis tends to promote further advance. In retrograde intussusception, Hession suggested that the proximal bowel slides over the stationary distal bowel. This would explain the frequent concurrence of retrograde intussusception with antegrade intussusception.4 In cases suggestive of recurrent obstruction, Karnak et al. recognized a line of weakening on the antimesenteric border of the bowel.5 We identify two possible mechanisms for the formation of retrograde intussusception of sigmoid colon. The large bowel is known to have weak antiperistaltic activity. These contractions may well initiate the intussusception in a retrograde fashion, especially in the presence of a mass lesion. The proximal bowel then slides over the intussuscepted area of the bowel through normal or exaggerated antegrade peristaltic waves. Of 11 cases reported in Japan, 10 were in the sigmoid colon and one (compound, with a retrograde component) in the transverse colon. This predilection for sigmoid colon favours the theory of initiation by antiperistaltic waves in the left colon.
We thank Mrs H Takenaka, from Teikyo School, for translations from Japanese.