What is the evaluation and management approach for a patient presenting with right upper quadrant (RUQ) pain and right lower quadrant (RLQ) tenderness?

Evaluation of RUQ Pain with RLQ Tenderness

Immediate Diagnostic Approach

Begin with right upper quadrant ultrasound as your first-line imaging test, but maintain high suspicion that the RLQ tenderness represents a separate pathology—most likely appendicitis—requiring CT abdomen/pelvis with IV contrast for definitive evaluation. 1, 2

This atypical presentation demands systematic evaluation of both anatomic regions, as the combination of RUQ pain with RLQ tenderness suggests either:

• Two distinct pathologic processes occurring simultaneously
• A single process with atypical pain referral patterns
• Perforated appendicitis with peritoneal irritation extending to the RUQ

Initial Imaging Strategy

Start with RUQ Ultrasound

• Order right upper quadrant ultrasound immediately, rated 9/9 (usually appropriate) by the American College of Radiology for RUQ pain evaluation 1, 3
• Ultrasound provides 96% accuracy for detecting gallstones, gallbladder wall thickening, pericholecystic fluid, and bile duct dilatation without radiation exposure 1, 3
• Ultrasound has 88% sensitivity for acute cholecystitis and can rapidly exclude or confirm biliary pathology as the source of RUQ pain 1

Proceed to CT Abdomen/Pelvis with IV Contrast

• Order CT abdomen/pelvis with IV contrast to evaluate the RLQ tenderness, as appendicitis is the most common cause of acute RLQ pain and CT is the most reliable imaging method for this evaluation 2
• CT with oral and IV contrast facilitates diagnosis of appendicitis and numerous other entities causing RLQ pain 2
• CT is essential because more than one-third of patients with acute RUQ pain do not have acute cholecystitis, and the RLQ tenderness strongly suggests a second pathology 4

Critical Laboratory Studies

• Obtain complete blood count with differential to assess for leukocytosis suggesting acute inflammation or infection 1
• Order comprehensive metabolic panel including liver function tests (AST, ALT, alkaline phosphatase, total and direct bilirubin) to evaluate for cholestatic patterns 3
• Add lipase to evaluate for pancreatitis, which can present with RUQ pain 1
• Obtain pregnancy test in all women of childbearing age before imaging, as ruptured ectopic pregnancy is a life-threatening "can't miss" diagnosis 1

Differential Diagnosis by Anatomic Region

RUQ Pain Sources

• Acute cholecystitis: gallbladder inflammation with fever, leukocytosis, and positive Murphy's sign 1
• Biliary colic: episodic severe pain from gallstones causing transient cystic duct obstruction 1
• Choledocholithiasis: common bile duct stones with elevated liver enzymes 1
• Acute cholangitis: requires triad of jaundice, fever/chills, and RUQ pain plus biliary dilatation on imaging 1
• Hepatic abscess or tumor (potentially ruptured): critical diagnosis requiring prompt attention 1

RLQ Tenderness Sources

• Appendicitis: most common cause of acute RLQ pain requiring urgent surgical evaluation 2
• Perforated appendicitis with peritonitis: can cause diffuse abdominal tenderness including RUQ 1
• Gynecologic pathology in women: ovarian torsion, tubo-ovarian abscess, or ectopic pregnancy 1

"Can't Miss" Diagnoses Requiring Immediate Recognition

• Ruptured ectopic pregnancy: life-threatening condition requiring urgent intervention 1
• Perforated gallbladder with peritonitis: critical diagnosis requiring immediate surgical consultation 1
• Mesenteric ischemia: life-threatening vascular emergency 1
• Pulmonary embolism: can present with upper abdominal pain 1

Algorithmic Decision-Making Based on Imaging Results

If Ultrasound Shows Acute Cholecystitis AND CT Shows Appendicitis

• Obtain immediate surgical consultation for management of both conditions 1
• Prioritize the more life-threatening pathology based on clinical presentation and imaging findings 1

If Ultrasound is Negative or Equivocal for Cholecystitis

• The CT abdomen/pelvis you ordered for RLQ evaluation will also assess the gallbladder and can detect complications like gangrene, perforation, or pericholecystic abscess 5
• Do not rely on CT alone for gallstones, as CT has only 75% sensitivity compared to ultrasound's 96% accuracy 1, 3
• If biliary pathology remains suspected despite negative ultrasound, proceed to MRCP with 85-100% sensitivity for choledocholithiasis 6

If CT Shows Appendicitis but Ultrasound is Negative

• Proceed with appendectomy as clinically indicated 2
• The RUQ pain may represent referred pain from appendicitis or peritoneal irritation 2

If Both Imaging Studies are Negative

• Consider MRCP to comprehensively evaluate the biliary tree for stones, strictures, or partial obstruction causing intermittent symptoms 6, 3
• Consider HIDA scan if acalculous cholecystitis or biliary dyskinesia is suspected with typical biliary-type pain 6, 3
• Reassess for non-GI causes including pulmonary embolism, pneumonia, or musculoskeletal pain 1, 7

Critical Pitfalls to Avoid

• Never order CT without IV contrast for suspected cholecystitis, as critical findings like gallbladder wall enhancement and adjacent liver parenchymal hyperemia cannot be detected without contrast 1
• Do not assume negative CT excludes cholelithiasis—ultrasound remains superior for detecting gallstones 1, 3
• Do not delay surgical consultation while awaiting additional imaging if clinical diagnosis of acute cholecystitis or appendicitis is evident 1
• Recognize that critically ill patients commonly have gallbladder abnormalities on ultrasound without true acute cholecystitis 1
• Do not skip the pregnancy test in women of childbearing age, as ectopic pregnancy can present with atypical pain patterns 1

When to Escalate Care Immediately

• Refer immediately to emergency department or acute surgical service if fever with leukocytosis suggests acute cholecystitis, cholangitis, or appendicitis 1
• Obtain urgent surgical consultation if imaging demonstrates perforation, abscess formation, or gangrenous changes in either the gallbladder or appendix 5, 1
• If patient is hemodynamically unstable or has peritoneal signs, prioritize CT with IV contrast over ultrasound to rapidly identify life-threatening complications 6