Intussusception is defined as the prolapse of a proximal bowel segment into a distal segment in the gastrointestinal tract. The mechanism of intussusception is still unknown and it is mostly common in children. 90% of intussusception cases are idiopathic and most lesions can safely be reduced. In contrast, adult intussusception is very rare and is found in only 1–5% of adult patients with bowel obstruction or ileus, accounting for 5–10% of all adult intussusceptions . The most common clinical symptom is abdominal pain with acute symptoms, often requiring emergency surgery [8–9]. Other symptoms include nausea, vomiting, palpable mass, bowel obstruction, changes in bowel habits, constipation, and diarrhea . In the present study, the most common symptom was abdominal pain and the duration of the symptom was relatively short (4.8 days). In addition, the rate of emergency surgery was also high at 53.6%, and 78.6% of the cases were hospitalized by visiting an emergency center. Abdomen CT appears to be the most important and sensitive diagnostic tool for making the preoperative diagnosis of intussusception in adults. Abdomen CT can also define the location, presence and characteristics of the tumor, its relationship to surrounding tissues, and its malignant stage . All the patients in the present study were diagnosed with adult intussusception with abdomen CT that confirmed the location of the cause or lesion, condition, degree of lesion, type of intussusception, and need for surgery. In the present study, the most common type of intussusception was entero-enteric (53.6%), followed by ileocolic (23.2%) and colo-colic (21.4%). Most existing researches report entero-enteric type as the most common intussusception type, ileocolic or ileocecal as the second most common type, and colocolic as the least common type [12–14].
A verifiable cause has been found in 64–90% of cases of adult intussusception. The malignancy in small bowel intussusception accounted for 12.5%-38.0% whereas most lesions (62.0–88.0%) in the small bowel were benign diseases, including benign neoplasms, Meckel’s diverticulum, adhesion, and inflammatory lesions [15–17]. A malignant tumor was the etiology in 48% of patients with colo-colonic intussusception . In the present study, unknown causes of adult intussusception accounted for 12.5%, malignancy tumor 30.4%, and benign tumor 30.4%.
Among the causes of adult intussusception, there are often rare cases that are not tumorous lesion. In the present study, postoperative intussusception following gastric surgery was found in 4 patients (7.1%). Three (3) cases were jejunojejunal intussusception (treatment: segmental resection) and 1 case was jejunogastric intussusception (treatment: manual reduction). Postoperative intussusception is a very rare complication after gastric surgery, with an incidence of less than 0.1% reported . Bozzi reported the first case of jejunogastric intussusception after gastrojejunostomy in 1914 , and the types include retrograde jejunogastric, jejunojejunal, jejunoduodenal and duodenogastric intussusception with no functional or mechanical leading cause . In the present study, 1 case developed into intussusception due to appendicitis. Appendiceal intussusception is a very rare condition with an incidence rate of 0.01% . Anatomical features such as redundant cecum, a wide appendiceal lumen and a thin or short mesoappendix have been associated with appendiceal intussusception [23–24]. In the present study, intussusception after colonoscopic polypectomy was found in 1 patient. Intussusception after colonoscopy is an extremely rare complication [25–26]. The mechanism is unknown, but the bowel edema secondary to a transmucosal burn may cause submucosal lifting. The post polypectomy electrocoagulation syndrome is caused by an injury to the colonic mucosa and muscularis layer after colonoscopic polypectomy, resulting in peritoneal inflammation with intussusception signs spotted by CT scans. Intussusception characteristics are presented within 12h of colonoscopy accompanied with abdominal pain at the site of the polypectomy, and is commonly resolved with conservative management [27–29]. The patient in the present study recovered after receiving conservative management. The present study found enteritis and ischemic colitis (10.7%) to be one of the causes of intussusception which is very rare. However, a previous case report has stated the cause of intussusception to be enteritis or ischemic colitis [30–32]. Most surgeons agree that adult intussusception requires standard surgical intervention due to high incidence of malignancy [33–34].
In conclusion, the present study reviewed the diagnosis and treatment of 56 adult intussusception patients. As shown in the study, adult intussusception is caused by various causes, thus the choice of treatment (surgical or conservative, resection or reduction, laparoscopy or open, and so on) must be determined through an accurate diagnosis before treatment.