Abdominal Ultrasound for Severe Epigastric Pain
For a patient with severe epigastric pain and soft abdomen, abdominal ultrasound is a reasonable initial imaging modality, but CT abdomen/pelvis with IV contrast is generally superior and should be strongly considered, especially if ultrasound is non-diagnostic or clinical suspicion remains high. 1
Initial Imaging Strategy
CT abdomen/pelvis with IV contrast is the preferred initial imaging for non-localized or epigastric abdominal pain in adults because it provides comprehensive evaluation of multiple potential etiologies and has superior diagnostic accuracy compared to ultrasound. 1 The ACR Appropriateness Criteria specifically recommend CT with IV contrast as "usually appropriate" for non-localized abdominal pain, which includes epigastric presentations. 1
However, ultrasound can serve as an effective initial screening tool in select circumstances, particularly when specific conditions are suspected:
- Ultrasound is the primary modality for suspected acute cholecystitis and other hepatobiliary causes of epigastric pain. 2, 3
- US can rapidly evaluate for biliary disease, liver pathology, and pancreatic abnormalities at the bedside in the emergency setting. 3
- Emergency bedside ultrasound is rapid, non-invasive, and can provide immediate diagnostic information for common epigastric pain etiologies. 3
Limitations of Ultrasound in This Context
Ultrasound has significant limitations that must be considered:
- US is operator-dependent and requires substantial expertise, with estimates suggesting 500 examinations needed for competency. 4
- Ultrasound accuracy is diminished in obese patients, which is particularly relevant in the United States population. 4
- US is less likely to identify alternative diagnoses compared to CT, with sensitivity for alternate diagnoses ranging 33-78% for US versus 50-100% for CT. 1
- Overlying bowel gas and patient body habitus can significantly limit visualization of deeper abdominal structures. 1
Recommended Algorithmic Approach
For your patient with severe epigastric pain and soft abdomen:
If biliary pathology is strongly suspected clinically (right upper quadrant tenderness, Murphy's sign, jaundice), start with ultrasound as it is the primary modality for cholecystitis. 2, 3
If the clinical picture is less specific or multiple etiologies are possible, proceed directly to CT abdomen/pelvis with IV contrast for comprehensive evaluation. 1
If ultrasound is performed first and is non-diagnostic or negative but clinical suspicion remains, proceed immediately to CT rather than repeating ultrasound. 1
Consider the patient's age and comorbidities: The history of Ankylosing Spondylitis may be a red herring, but older patients or those with atypical presentations benefit more from CT's comprehensive evaluation. 1
Critical Pitfalls to Avoid
Do not rely solely on ultrasound when:
- The patient is obese or has significant bowel gas limiting acoustic windows. 4
- Multiple potential diagnoses need to be excluded (pancreatitis, perforation, mesenteric ischemia, aortic pathology). 1
- The clinical presentation is severe or suggests potential surgical pathology. 1
Do not delay definitive imaging with CT if ultrasound is equivocal, as this can delay diagnosis and appropriate management. 1 The soft abdomen in your patient does not exclude serious pathology, and severe pain warrants thorough investigation.
Special Considerations for Ankylosing Spondylitis
While the patient's AS history is noted, there is no specific evidence suggesting AS changes the imaging approach for acute epigastric pain. The standard algorithm based on pain characteristics and suspected pathology should guide imaging selection. 1
In summary: CT abdomen/pelvis with IV contrast provides the most comprehensive evaluation for severe epigastric pain with uncertain etiology, while ultrasound is appropriate as initial imaging only when biliary pathology is specifically suspected or as a rapid bedside screening tool with the understanding that CT will likely follow if non-diagnostic. 1, 2