What is the appropriate workup for a patient presenting with right upper abdominal pain?

Workup of Right Upper Abdominal Pain

Ultrasonography of the abdomen is the first-line imaging study for right upper quadrant pain, with the highest appropriateness rating (9/9) from the American College of Radiology, and should be obtained after initial laboratory evaluation. 1, 2

Initial Laboratory Testing

Obtain the following labs before imaging:

• Complete blood count (CBC) to assess for leukocytosis indicating infection or inflammation 2, 3
• Liver function tests (ALT, AST, alkaline phosphatase, GGT, bilirubin) to evaluate hepatobiliary disease 3, 4
• Pancreatic enzymes (amylase and lipase) to rule out pancreatitis 3, 4
• Pregnancy test for all females of reproductive age before any imaging to avoid unnecessary radiation and identify pregnancy-related conditions 2, 3
• Urinalysis to evaluate for renal stones or infection 2

First-Line Imaging: Ultrasonography

Ultrasound is superior to CT as initial imaging because it provides excellent evaluation of gallbladder pathology (the most common cause of RUQ pain), has no radiation exposure, is readily available, and can identify liver abnormalities and other causes of RUQ pain. 1, 2, 5

Key advantages of ultrasound:

• Detects acute cholecystitis with high sensitivity 1, 5
• Identifies cholelithiasis and gallbladder wall thickening 1, 5
• Evaluates hepatic, pancreatic, renal, and vascular pathology 5
• Dynamic examination allows real-time assessment 5

Second-Line Imaging Options

If ultrasound is negative or equivocal and symptoms persist, consider:

MRI with MRCP (Magnetic Resonance Cholangiopancreatography)

• Superior to CT for biliary sources of RUQ pain with sensitivity of 85-100% for cholelithiasis/choledocholithiasis 1
• Excellent for visualizing the cystic duct and common bile duct 1
• Distinguishes acute from chronic cholecystitis based on T2 signal characteristics 1
• Appropriateness rating of 6/9 2

CT abdomen with contrast

• May demonstrate acute cholecystitis if ultrasound is negative 1
• Useful for clarifying sonographic findings and identifying non-biliary causes 1
• Appropriateness rating of 6/9 2
• Not first-line due to radiation exposure, especially in younger patients 2, 3

Tc-99m Cholescintigraphy (HIDA scan)

• Particularly valuable for suspected chronic cholecystitis with intermittent symptoms 1
• Evaluates for partial biliary obstruction and sphincter of Oddi dysfunction 1
• Appropriateness rating of 6/9 2

Clinical Scenarios Requiring Different Approaches

Suspected acute cholecystitis (fever, elevated WBC)

• Ultrasound remains first-line 1
• If ultrasound is diagnostic, proceed to treatment 1
• If equivocal, consider HIDA scan or MRI with MRCP 1, 2

No fever or leukocytosis, suspected biliary disease

• Start with ultrasound 1
• If negative, MRI with MRCP is superior to CT for further evaluation 1
• Consider HIDA scan for chronic or intermittent symptoms 1

Critical Pitfalls to Avoid

• Never skip pregnancy testing in reproductive-age females before imaging—this prevents unnecessary radiation exposure and identifies ectopic pregnancy 2, 3
• Do not use CT as first-line imaging in younger patients due to radiation concerns when ultrasound is highly effective 2, 3
• Do not rely solely on laboratory tests without appropriate imaging when clinical suspicion remains high 2, 3
• Conventional radiography (plain X-rays) has minimal diagnostic value for RUQ pain and should not be routinely ordered 1, 3
• Over one-third of patients initially suspected to have acute cholecystitis have alternative diagnoses—ultrasound can identify hepatic, pancreatic, renal, vascular, and other causes 5

Algorithmic Approach

1. Obtain pregnancy test (if female of reproductive age) + CBC + LFTs + amylase/lipase + urinalysis 2, 3
2. Order ultrasound of abdomen as first imaging study 1, 2
3. If ultrasound is diagnostic, proceed to treatment 1
4. If ultrasound is negative/equivocal and symptoms persist:
   • For suspected biliary disease: MRI with MRCP 1
   • For intermittent/chronic symptoms: HIDA scan 1
   • For broader differential: CT abdomen with contrast 1, 2