Version July 2025
| Lesion | Etiology | Risk factors |
| Extrinsic lesions | Adhesions | Prior surgery, diverticulitis, Crohn disease, VP shunt, peritonitis (eg, tuberculous peritonitis) |
| Hernia (congenital, acquired) | Abdominal wall hernia, inguinal hernia, femoral hernia, diaphragmatic hernia | |
| Volvulus | Chronic constipation, congenital abnormal mesenteric attachments | |
| Intra-abdominal abscess | Diverticulitis, appendicitis, Crohn disease | |
| Peritoneal carcinomatosis | Ovarian cancer, colon cancer, gastric cancer | |
| Endometriosis | ||
| Sclerosing mesenteritis | Prior surgery, abdominal trauma, autoimmune disorders, malignancy, neuroendocrine tumor | |
| Desmoid tumor/other soft tissue sarcoma (rare) | ||
| Superior mesenteric artery syndrome | Rapid weight loss | |
| Intrinsic lesions | Congenital malformations, atresia, duplication | Refer to appropriate topic reviews |
| Large bowel neoplasm | ||
| Adenocarcinoma | Hereditary colorectal cancer syndromes (HNPCC, FAP), inflammatory bowel disease, bowel irradiation, others (refer to appropriate topic reviews) | |
| Desmoid | ||
| Carcinoid | ||
| Neuroendocrine tumor | ||
| Lymphoma | ||
| Small bowel neoplasm* | ||
| Adenocarcinoma | Hereditary cancer syndromes (HNPCC, FAP, Peutz-Jeghers, MUTYH-associated polyposis, attenuated FAP) | |
| Leiomyosarcoma | ||
| Paraganglioma | ||
| Schwannoma | ||
| Metastatic disease | Melanoma, breast cancer, cervical cancer, colon cancer (refer to appropriate topic reviews) | |
| Gastrointestinal stromal tumor | ||
| Neuroendocrine tumor | ||
| Lymphoma | Chronic inflammation | |
| Benign lesions | Peutz-Jeghers polyps, xanthomatosis, leiomyoma | |
| Anastomotic stricture | Prior intestinal surgery | |
| Inflammatory stricture | Crohn disease, diverticular disease, NSAID enteropathy | |
| Ischemic stricture | Peripheral artery disease, aortic surgery, colon resection | |
| Radiation enteritis/stricture | Prior abdominal or pelvic irradiation | |
| Intraluminal obstruction of normal bowel | Intussusception* | Small bowel tumor* |
| Gallstones | Cholecystitis | |
| Congenital webs | ||
| Feces or meconium | Cystic fibrosis, severe constipation | |
| Bezoar (phytobezoar, pharmacobezoar) | Intestinal motility disorders | |
| Intramural hematoma | ||
| Traumatic | Blunt abdominal trauma | |
| Spontaneous | Antithrombotic therapy | |
| Foreign body | ||
| Ingested | Psychiatric disturbance | |
| Medical device migration | PEG tube, jejunal tube | |
| Parasites | Ascaris lumbricoides, Strongyloides stercoralis | |
