duodenal narrowing or obstruction

congenital (see double bubble sign)
- duodenal atresia: neonatal presentation
- annular pancreas: infants or adults
- duodenal web/diaphragm, Ladd's bands
- duplication cyst
inflammatory
- postbulbar ulcer
- Crohn disease
- infections: TB, Strongyloides
- pancreatitis
- pancreatic pseudocyst
- radiation injury
malignant
- duodenal adenocarcinoma/lymphoma
- pancreatic carcinoma
- metastatic disease
traumatic
- intramural hematoma
vascular
- superior mesenteric artery syndrome