Imaging Guidelines for Abdominal Pain

Primary Recommendation: CT Imaging

The American College of Radiology recommends CT of the abdomen and pelvis with IV contrast as the next appropriate imaging study after a negative ultrasound in patients with persistent acute abdominal pain 1, 2, 3
Obtaining ultrasound followed by CT in patients with negative or inconclusive ultrasound results offers the best sensitivity for detecting disease in nonpregnant adult patients 2, 4

The American College of Radiology suggests using IV contrast whenever possible for optimal evaluation of vascular structures, bowel wall enhancement, and soft tissue pathology 1, 2, 3
Scanning the entire abdomen and pelvis is recommended rather than limiting coverage based on symptoms—limited scanning visualized all acute pathology in only 33% of abnormal cases 1
If IV contrast is contraindicated, non-contrast CT is still appropriate but has reduced sensitivity 3

MRI of the abdomen and pelvis without and with IV contrast can provide clinically useful information when CT is not ideal 3
The American College of Radiology recommends MRI as the preferred next step in pregnant patients with negative or equivocal ultrasound findings, avoiding radiation exposure 2, 4, 3

A complete blood count (CBC) should be obtained to assess for leukocytosis indicating infection or inflammation 6, 5
A comprehensive metabolic panel (CMP) including liver function tests (ALT, AST, alkaline phosphatase, bilirubin) should be obtained 6, 5
Serum lipase (more specific than amylase) should be obtained for suspected pancreatitis 6
Urinalysis should be obtained to evaluate for urinary tract infection or nephrolithiasis 6, 5
Beta-hCG testing is mandatory in all women of reproductive age before proceeding with CT to rule out ectopic pregnancy 6, 5, 7

Tachycardia is the most sensitive early warning sign of surgical complications and should trigger urgent investigation 5, 7
Severe pain out of proportion to physical examination findings suggests mesenteric ischemia 7
Fever with abdominal pain suggests infection or abscess requiring immediate imaging 3, 7
Signs of peritonitis (rigid abdomen, rebound tenderness) require urgent evaluation 7
Repeat abdominal CT after initially negative CT has low diagnostic yield, dropping from 22% on initial presentation to 5.9% on the fourth CT or greater 1
Clinical factors predicting higher diagnostic yield on repeat CT include leukocytosis and elevated APACHE-II scores 1
CT in patients with abdominal pain plus diarrhea changed management in only 11% versus 53% in patients with pain alone—use a thoughtful approach in this setting 1
Elderly patients have a higher likelihood of malignancy, diverticulitis, and vascular causes, and may present with atypical symptoms requiring more thorough evaluation even with normal labs 5, 7
Women of reproductive age should always be considered for gynecologic conditions including ectopic pregnancy, ovarian torsion, and pelvic inflammatory disease 5, 7
Post-operative patients should undergo CT with IV contrast to evaluate for postoperative abscesses, leaks, or hemorrhage 3