Intussusception in adults is an uncommon condition, representing 1% of cases of adult bowel obstruction and less than 1% of hospital admissions [
4]. It is a common cause of bowel obstruction in infants, in whom it presents with a classic triad of symptoms and signs: crampy abdominal pain, a palpable sausage-shaped mass mainly in the right upper quadrant, and currant jelly stools [
5]. In one case series, it was noted that adult intussusception was slightly more predominant among men, with a male:female ratio of 1.8:1 [
1]. Adult intussusception may present with acute, sub-acute, or chronic non-specific features, which makes its diagnosis difficult. In our patient, sub-acute non-specific complaints of backache during strenuous activity culminated in acute prolapsed intussusception of the sigmoid. In one series, computed tomography, with an accuracy of 58% to 100%, was the most efficient tool in diagnosing intussusception, followed by abdominal ultrasound [
1,
2]. In our patient, the mass was obviously protruding from the anus and did not warrant any complex investigations. Our case could possibly have been confused with complete rectal prolapse. A retrospective study by Rashid and Basson [
6] showed that patients with rectal prolapse exhibited a 4.2-fold relative risk for colorectal cancer compared with the comparative group. In our patient, the diagnosis of colorectal cancer was at the top of the list as the underlying cause of intussusception, mainly because of his age at presentation. With regard to the management of adult sigmoid intussusception, several schools of thought exist. However, there is a common consensus that the treatment of choice is resection of the affected portion of the sigmoid colon, as the results reported in several series have revealed that 90% of cases have an underlying pathology. Lynn and Agrez [
7] reported the case of a patient with sigmoid colon intussusception in whom the rectum was opened circumferentially by using diathermy at the point of the intussusception and the intussuscepted sigmoid colon was removed from the rectum through the anus. However, this procedure could cause contamination of the abdominal cavity. In our case, given that the intussusceptum was edematous and gangrenous, a longitudinal incision was made on the prolapsed bowel to facilitate reduction with a milking motion. A decision to perform reduction was made after assessing the abdominal viscera and the presence of mesenteric lymph nodes for any macroscopic evidence of a large bowel tumor. We did a spectacle colostomy after resection of the gangrenous bowel, as the viability of the sigmoid colon could not be guaranteed for primary end-to-end anastomosis.
While 70% to 90% of adult intussusceptions have an identifiable cause or lesion, most pediatric intussusceptions are idiopathic [
1,
2]. The case of an elderly patient presented here was of the uncommon idiopathic type with no identifiable cause found in the history, physical examination, or histological findings.