What is the appropriate evaluation and management for a patient with right upper quadrant abdominal pain radiating to the shoulder?

Evaluation of Right Upper Quadrant Abdominal Pain Radiating to the Shoulder

Begin with right upper quadrant ultrasound immediately—this is the single most appropriate initial imaging study, rated 9/9 by the American College of Radiology, and should be performed before any other imaging modality. 1

Clinical Significance of Shoulder Radiation

• Pain radiating to the right shoulder strongly suggests diaphragmatic irritation from gallbladder inflammation, as the phrenic nerve (C3-C5) shares dermatomal distribution with the shoulder region 2, 3
• This referred pain pattern is highly characteristic of acute cholecystitis and should elevate your clinical suspicion for biliary pathology requiring urgent evaluation 1

Initial Diagnostic Workup

Laboratory Studies

• Order a complete blood count to assess for leukocytosis (white blood cell count >10,000/μL suggests acute inflammation) 1, 3
• Obtain a complete metabolic panel including liver function tests (AST, ALT, alkaline phosphatase, total and direct bilirubin) to evaluate for hepatobiliary pathology 4, 3
• Check lipase if there is any epigastric component to the pain, as pancreatitis can present similarly 3
• Obtain urinalysis to exclude urolithiasis as an alternative diagnosis 3
• Perform pregnancy testing in all patients with female reproductive organs to exclude ectopic pregnancy 3

Physical Examination Findings to Document

• Assess for Murphy's sign (inspiratory arrest during deep palpation of the right upper quadrant), though this has relatively low specificity and is unreliable if the patient has received pain medication 5
• Check for fever, which raises clinical suspicion for acute cholecystitis, abscess, or ascending cholangitis 1
• Evaluate for peritoneal signs (guarding, rebound tenderness) which suggest complications such as perforation 6
• Document the presence of jaundice, which indicates biliary obstruction requiring different management 5

Imaging Algorithm

First-Line: Right Upper Quadrant Ultrasound

• Ultrasound has 81% sensitivity and 83% specificity for acute cholecystitis and 96% accuracy for detecting gallstones 1, 7
• Ultrasound evaluates gallbladder wall thickening (>3mm), pericholecystic fluid, gallstones, bile duct dilatation, and can identify alternative diagnoses 1, 7
• Ultrasound is faster, portable, radiation-free, and less expensive than CT or MRI 1, 8
• A normal gallbladder wall appearance makes acute gallbladder pathology very unlikely 1

Second-Line Imaging Based on Ultrasound Results

If ultrasound shows gallstones with fever and elevated WBC:

• Proceed to cholescintigraphy (HIDA scan) if ultrasound findings are equivocal for acute cholecystitis 1
• Cholescintigraphy has superior diagnostic performance with 96% sensitivity and 90% specificity for acute cholecystitis, better than ultrasound 1
• Gallbladder nonvisualization on HIDA scan with delayed imaging or morphine augmentation is highly accurate for confirming acute cholecystitis 1

If ultrasound is negative or nondiagnostic:

• Order CT abdomen and pelvis with IV contrast to evaluate for alternative diagnoses and complications 1
• CT has a negative predictive value approaching 90% for acute cholecystitis and can detect complications such as gangrene, emphysematous cholecystitis, hemorrhage, and perforation 1
• CT is particularly useful for preoperative planning, as absence of gallbladder wall enhancement or presence of a stone in the infundibulum predicts higher conversion rates from laparoscopic to open cholecystectomy 1

If biliary obstruction is suspected (elevated bilirubin, dilated bile ducts on ultrasound):

• Proceed directly to MRCP, which has 85-100% sensitivity and 90% specificity for detecting choledocholithiasis and biliary obstruction 1, 4, 5
• MRCP is superior to CT for assessing biliary sources of right upper quadrant pain and provides comprehensive visualization of the cystic duct and common bile duct 1, 4, 5
• MRCP can identify the level and cause of biliary obstruction including stones, strictures, masses, and lymph nodes 1, 5

Critical Pitfalls to Avoid

• Do not skip ultrasound and proceed directly to CT unless the patient is hemodynamically unstable, as ultrasound is more appropriate for initial evaluation and avoids unnecessary radiation exposure 4, 8
• Do not order CT as the primary imaging study for right upper quadrant pain, as it has only 75% sensitivity for gallstones and exposes patients to radiation when ultrasound is diagnostic in most cases 1, 8
• Do not assume normal laboratory values exclude serious pathology in elderly patients, as many laboratory tests are nonspecific and may be normal despite serious infection in this population 1
• Do not order HIDA scan as the primary test for elevated liver function tests and right upper quadrant pain unless acute cholecystitis is the primary clinical concern, as elevated LFTs indicate biliary obstruction requiring anatomic visualization with MRCP 5
• Do not delay imaging in patients with fever and right upper quadrant pain, as the need for quick, definitive diagnosis is considerably heightened when fever is present 1

When to Consider Urgent Surgical Consultation

• Peritoneal signs suggesting perforation or gangrenous cholecystitis 1
• Hemodynamic instability with right upper quadrant pain 6
• Imaging findings of complicated cholecystitis (emphysematous, hemorrhagic, gangrenous, or perforated) 1
• Ascending cholangitis (Charcot's triad: fever, jaundice, right upper quadrant pain) requiring urgent biliary decompression 5