Hypochloremic acidosis with increased anion gap may occur with strangulated obstruction. Serum amylase may be elevated with bowel infarction. Radiography Plain films Small bowel obstruction. Plain radiographs may demonstrate multiple air-fluid levels with dilated loops of small intestine, but no colonic gas. Proximal jejunal obstruction may not cause dilatation.
Distal obstruction is characterized by a ladder pattern of Colonic obstruction.
Obstructive lesions usually are located in the left colon and rectum and cause distention of the proximal Endoscopy Upper endoscopy is the best test in obstruction of the gastric outlet or duodenum. Colonoscopy can confirm the diagnosis of colon obstruction by cancer.