In intestinal obstruction, investigations needed are -a) Barium swallowb) Intestinal barium mealc) Stomach barium meald) Erect X-ray abdomene) Supine X-ray abdomen
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The diagnosis of intestinal obstruction is suspected in any patient presenting with abdominal pain, vomiting, distension and obstipation.
Plain radiographs usually confirm the clinical suspicion and can also define the site of obstruction.


Maingot's 10/e, p 1163 writes that 4 x-ray views of the abdomen are essential in all pts. suspected of intestinal obstruction.
i) upright chest, upright abdomen, iii) supine abdomen & iv) left lateral decubitus view.
whereas Sabiston, Harrison & CSDT write for only 2 views - the erect abdomen & the supine abdomen.
Also know that Bailey 24/e, p 1189 writes that "Erect abdominal films are no longer routinely obtained and the radiological diagnosis is based on a supine abdominal film. An erect film may subsequently be requested when further doubt exists"
Other investigations which may be done are:

CT scan

CT is useful in cases in which diagnosis is not readily apparent by plain abdominal film, or if an abdominal tumor or abscess is suspected to be the cause of obstruction.
CT is helpful in identifying the location and cause of obstruction.

Barium studies

A barium enema is done if a large bowel obstruction is suspected.
Barium studies for small bowel obstructions are
Barium meal follow through (BMFT)
Enteroclysis (small bowel enema)
these studies are done in patients in whom a recurring or low-grade mechanical obstruction is suspected.
these studies are contraindicated in acute obstructions - Bailey 24/e, p 1190
BMFT & enteroclysis are also contraindicated in large bowel obstruction as barium may get insipissated in the colon.