What's the next step in evaluating a patient with persistent or recurrent abdominal pain and a previous negative abdominal computed tomography (CT) scan?

Workup of Persistent Abdominal Pain After Negative CT

If a patient has persistent or recurrent abdominal pain after a negative abdominal CT, the next step depends critically on timing and clinical context: for acute presentations within days, repeat CT with IV contrast at 12-24 hours is warranted if clinical suspicion remains high; for chronic symptoms beyond the acute window, shift to alternative modalities including MRI, ultrasound, or specialized studies like CT enterography rather than repeating standard CT. 1, 2

Timing-Based Algorithm for Repeat Imaging

Acute Presentation (Within 12-24 Hours)

• Repeat CT with IV contrast within 12-24 hours if the patient remains hemodynamically stable but has persistent abdominal pain, elevated/rising amylase or lipase, or high clinical suspicion for missed pancreatic, duodenal, or biliary injury 1
• The diagnostic yield of early repeat CT (within 2-3 days) is approximately 23%, with 73% of newly identified pathology being bowel-related 3
• IV contrast administration is essential for the repeat study, as it significantly improves detection of bowel pathology and mesenteric ischemia 1, 3

Subacute to Chronic Presentation (Days to Weeks)

• Do not routinely repeat standard CT for low-risk recurrent abdominal pain, as the diagnostic yield drops dramatically (from 22% on initial CT to 5.9% on fourth or subsequent CTs) 1
• Clinical predictors that may justify repeat imaging include leukocytosis and elevated APACHE-II scores 1
• The mean interval for positive findings on repeat CT is approximately 2.0 days; beyond this window, alternative approaches are more appropriate 3

Alternative Diagnostic Modalities

MRI Abdomen/Pelvis

• MRI with or without contrast is the preferred next step for persistent unexplained abdominal pain after negative CT, particularly when CT technology or technique may have limitations 1
• Rapid MRI protocols (acquisition time <10 minutes) demonstrate 99% overall accuracy for diagnosing bowel inflammation, obstruction, pancreaticobiliary disease, renal inflammation, and gynecological processes 1
• MRI with hepatobiliary contrast (MRCP) is specifically indicated for suspected pancreatic ductal or biliary injuries missed on initial CT 1
• Noncontrast MRI can be highly effective, with one study showing 99% accuracy using protocols under 2 minutes 1

Ultrasound

• Ultrasound should be reconsidered for hepatobiliary disease, renal abnormalities, and gynecological pathology, despite lower overall sensitivity (75%) compared to CT (88%) for intra-abdominal abscesses 1
• Contrast-enhanced ultrasound may have diagnostic value in stable patients with suspected pancreatic injury 1
• Ultrasound has similar sensitivity to CT for acute cholecystitis 1

Specialized CT Techniques

• CT enterography should be considered for persistent unexplained abdominal pain when small bowel pathology is suspected, as it can detect lesions missed on routine CT (including small bowel tumors like carcinoids) 4
• Standard abdominal CT has limited sensitivity for certain conditions, with a negative predictive value of only 64% for upper abdominal pathology, commonly missing pancreaticobiliary inflammatory processes, gastritis, and duodenitis 1

Clinical Reassessment Strategy

Serial Examination and Laboratory Monitoring

• Serial clinical examination is essential and should be combined with repeated measurement of serum amylase and lipase starting 3-6 hours after initial injury or presentation 1
• Elevated or increasing amylase/lipase levels without definitive diagnosis mandate more accurate investigation 1
• The presence of fever, leukocytosis, or failure of bowel function to return to normal indicates high risk for intra-abdominal infection requiring additional intervention 1

When to Consider Diagnostic Laparoscopy

• Diagnostic laparoscopy is indicated when patients are clinically deteriorating with suspected duodenal-pancreatic or biliary injuries and imaging remains equivocal 1
• During surgical exploration, intraoperative cholangiogram is strongly recommended when biliary injury is suspected but not identified 1

Common Pitfalls to Avoid

• Do not bypass stepwise evaluation in non-acute settings by immediately repeating CT, as this exposes patients to unnecessary radiation (10-30 mSv effective dose) without evidence of benefit 2, 5
• Do not confuse chronic intermittent symptoms with acute indications for CT; chronic symptoms require ultrasound or plain radiography first per ACR Appropriateness Criteria 2
• Do not order repeat CT without IV contrast when bowel pathology is suspected, as 75% of positive follow-up findings are bowel-related and require contrast for detection 3
• Do not rely on plain radiography for workup of persistent abdominal pain, as it has limited sensitivity (43-49%) for most pathology and no role in abscess detection 1, 2
• Do not assume the initial CT was adequate without verifying that IV contrast was used and appropriate technique was employed; reduced segmental bowel-wall enhancement (100% specific for infarction) requires IV contrast 1

Nuclear Medicine and PET Considerations

• FDG-PET/CT may be useful as an adjunct when cross-sectional imaging is inconclusive and there is concern for infectious, inflammatory, or neoplastic processes, particularly in fever of unknown origin 1
• Older nuclear medicine studies (gallium, indium/technetium leukocyte scans) suggested utility for abdominal infections when CT is negative, but CT technology has significantly advanced since these studies were published in the 1980s-1990s 1
• Cholescintigraphy has a specific role if there is particular concern for gallbladder or hepatobiliary disease 1

Extra-Abdominal Considerations

• Always consider extra-abdominal sources including nosocomial pneumonia, urinary tract infection, venous thrombosis, pulmonary embolism, and C. difficile disease (even without diarrhea) when intra-abdominal imaging is negative 1
• If no evidence of infection is found after careful investigation, termination of antimicrobial therapy is warranted rather than continuing empiric treatment 1