Best investigation for acute intestinal obstruction is:

Diagnosis - X-ray Abdomen: Confirm the clinical suspicion and define more accurately the site of obstruction (60% diagnostic accuracy) Supine radiographs: Dilated loops of small intestine without evidence of colonic distention, diagnose site and level of obstruction. Erect radiographs: Multiple air-fluid levels, which often layer in a step wise pattern Supine films are better than erect for diagnosis of intestinal obstruction CT SCAN Used in complex patients, in whom the diagnosis is not readily apparent Highly sensitive for diagnosing complete or high-grade obstruction of the small bowel and for determining the location and cause of obstruction. Less sensitive for paial small bowel obstruction. Useful for extrinsic cause of bowel obstruction (e.g. abdominal tumors, inflammatory disease, or abscess) and determining bowel strangulation. - Enteroclysis is investigation of choice in low-grade, intermittent SBO. - Barium studies: Precisely demonstrate the level of the obstruction and cause in ceain cases - Ultrasound: Useful in pregnant patients.