What is the appropriate evaluation and management for a patient with a RUQ (Right Upper Quadrant) knot and tenderness on palpation?

Evaluation and Management of Right Upper Quadrant Mass with Tenderness

Ultrasound is the initial imaging modality of choice for a palpable RUQ mass with tenderness, as it rapidly identifies biliary pathology, gallstones, and alternative diagnoses while avoiding radiation and allowing real-time assessment of the sonographic Murphy sign. 1

Initial Diagnostic Approach

Clinical Assessment

• Evaluate for biliary disease features: fever, jaundice, elevated white blood cell count, and signs of acute cholecystitis 1
• Assess the mass characteristics: location relative to the gallbladder, mobility, size, and whether tenderness is focal or diffuse 1
• Consider non-biliary etiologies: hepatic masses, abscesses, or musculoskeletal causes if the mass is superficial 1

First-Line Imaging: Ultrasound

Ultrasound should be performed immediately as it provides multiple diagnostic advantages 1, 2:

• Identifies gallstones with high sensitivity (primary focus of RUQ ultrasound) 1
• Detects acute cholecystitis with 88% sensitivity through findings of gallbladder wall thickening (>3mm), pericholecystic fluid, and sonographic Murphy sign 1
• Evaluates for complications: emphysematous cholecystitis (gas in wall), gangrenous changes, or perforation 1
• Assesses bile ducts for dilatation or choledocholithiasis 1
• Non-invasive, portable, and rapidly available without radiation exposure 1

Key Ultrasound Pitfalls to Avoid

• Gallbladder may be confused with portal vein, IVC, or hepatic cysts—scan in multiple planes for accurate identification 1
• Chronic cholecystitis may present as a contracted, stone-filled gallbladder that is difficult to visualize 1
• Small stones in the gallbladder neck can be mistaken for edge shadow artifacts 1
• Obesity and bowel gas limit examination quality 1

Subsequent Imaging Based on Ultrasound Results

If Ultrasound is Equivocal or Negative but Clinical Suspicion Remains High

CT abdomen with IV contrast is the next appropriate study 1:

• Confirms or refutes cholecystitis with 90% negative predictive value 1
• Identifies complications: gangrene, gas formation, hemorrhage, perforation, or adjacent liver hyperemia 1
• Detects alternative diagnoses: hepatic masses, abscesses, pancreatic pathology, or other causes of RUQ pain 1, 3
• Aids preoperative planning: absence of gallbladder wall enhancement or infundibular stone predicts conversion from laparoscopic to open cholecystectomy 1

Important caveat: CT has only 75% sensitivity for gallstones (density-dependent), so negative CT does not exclude cholelithiasis 1

If Both Ultrasound and CT Are Equivocal

For suspected acute cholecystitis specifically 1:

• Tc-99m HIDA scan is the gold standard with 97% sensitivity and 90% specificity for acute cholecystitis 1
• MRI/MRCP provides superior bile duct visualization (85-100% sensitivity for choledocholithiasis) and differentiates acute from chronic cholecystitis based on T2 signal characteristics 1

Choose HIDA if: acute cholecystitis is the primary concern and anatomic detail is less critical 1

Choose MRI/MRCP if: biliary ductal pathology, masses, or comprehensive hepatobiliary evaluation is needed 1

Special Considerations

Non-Biliary Causes of RUQ Mass

If imaging excludes biliary pathology, consider 3, 2:

• Hepatic lesions: tumors, abscesses (ultrasound can identify but may require CT/MRI for characterization) 1
• Musculoskeletal: abdominal wall masses or hernias (clinical examination with targeted imaging) 1
• Renal pathology: upper pole masses or hydronephrosis (visible on ultrasound) 2

Critical "Can't Miss" Diagnoses

Always consider life-threatening alternatives even with biliary findings 1:

• Myocardial infarction (atypical presentation)
• Aortic aneurysm
• Pulmonary embolism with pleuritic pain

Pregnant Patients

Ultrasound or MRI are preferred initial modalities to avoid radiation exposure 1

Management Algorithm Summary

1. Perform ultrasound immediately for any RUQ mass with tenderness 1, 2
2. If acute cholecystitis confirmed: surgical consultation for cholecystectomy 1
3. If ultrasound equivocal: proceed to CT with IV contrast for comprehensive evaluation 1
4. If both equivocal and cholecystitis suspected: HIDA scan for definitive diagnosis 1
5. If biliary ductal pathology suspected: MRI/MRCP for superior ductal visualization 1

Common pitfall: Do not delay ultrasound for laboratory results or other testing—imaging should occur as soon as the clinical decision is made that sonographic evaluation is needed 1