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Intestinal Obstruction

Intestinal obstruction is characterized by nausea, vomiting, cramps, and obstipation. Suspected intestinal obstruction requires immediate evaluation.

Small bowel obstruction. Auscultation may reveal high-pitched rushes or tinkles that coincide with episodes of cramping. Pain usually is

Proximal obstruction. Frequent non-bilious vomiting is prominent if the obstruction is proximal to the ampulla of Vater. Colicky pain occurs at frequent intervals (2-5 minutes). Obstipation may not occur until later.

Distal obstruction. Vomiting is bilious and less frequent. The vomiting may be feculent if the obstruction has been long-standing. Colicky pain occurs at intervals of 10 minutes or more, and it is less intense. A dull ache may persist between cramps.

Colonic obstruction

Colonic obstruction is caused by colon cancer in 60-70% of cases, and diverticulitis and volvulus account for 30%. obstruction is more common in the left colon.

Milder attacks of pain often occur in the weeks preceding the acute episode. Colic is perceived in the lower abdomen or suprapubically, and obstipation and distention are characteristic. Nausea is common, and vomiting may occur.

Tenderness is usually mild in uncomplicated colonic obstruction. Rectal exam or sigmoidoscopy may detect an the obstructing lesion.

Colonic pseudo-obstruction (Ogilvie's syndrome) may occur in the elderly, bedridden or institutionalized individual, often after recent cardiac, abdominal or orthopedic surgery.

Strangulated obstruction is characterized by constant pain, fever, tachycardia, peritoneal signs, a tender abdominal mass, and leukocytosis.

Laboratory evaluation of intestinal obstruction

Hypokalemic alkalosis is the most common metabolic abnormality resulting from vomiting and fluid loss. Elevated BUN and creatinine suggests significant hypovolemia. Hypochloremic acidosis with increased anion gap may occur with strangulated obstruction.

Leukocyte count frequently is normal in uncomplicated obstruction; however, leukocytosis suggests strangulation.

Serum amylase may be elevated with bowel infarction.


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.

Colonic obstruction. Obstructive lesions usually are located in the left colon and rectum and cause distention.


Upper endoscopy is the best test in obstruction of the gastric outlet or duodenum.

Colonoscopy can confirm the diagnosis of colon obstruction by cancer. Non-strangulated volvulus can often be reduced endoscopically, and elective resection can be completed.