What is the differential diagnosis for a patient presenting with right upper quadrant (RUQ) pain?

Differential Diagnosis for Right Upper Quadrant Pain

The differential diagnosis for RUQ pain is broad and requires systematic evaluation across multiple organ systems, with biliary disease being the most common but representing only two-thirds of cases. 1, 2

Biliary and Gallbladder Causes

Acute cholecystitis is the most common diagnosable cause of RUQ pain in emergency presentations, though over one-third of patients initially suspected to have acute cholecystitis actually have alternative diagnoses. 2, 3

• Acute cholecystitis - characterized by gallbladder inflammation, often with gallstones, fever, and positive Murphy's sign 4, 5
• Biliary colic - episodic severe pain from gallstones causing transient cystic duct obstruction, typically radiating to right shoulder or back 4
• Choledocholithiasis - common bile duct stones causing obstruction and elevated liver enzymes 4
• Acalculous cholecystitis - gallbladder inflammation without stones, seen in critically ill patients 6
• Cholangitis - biliary infection requiring urgent intervention 3
• Sphincter of Oddi dysfunction - functional biliary disorder causing delayed transit to small bowel 6

Hepatic Causes

• Hepatitis (viral, alcoholic, drug-induced) - presents with elevated transaminases and may have jaundice 4, 2
• Hepatic abscess - pyogenic or amebic, with fever and leukocytosis 2
• Hepatomegaly from various causes including congestive heart failure 4
• Budd-Chiari syndrome - hepatic vein thrombosis 2
• Portal vein thrombosis 2

Pancreatic Causes

• Acute pancreatitis - elevated amylase/lipase, often with epigastric pain radiating to back 4, 2
• Pancreatic mass or pseudocyst 2

Renal and Urologic Causes

• Nephrolithiasis - right kidney stones causing flank pain radiating anteriorly 2, 7
• Pyelonephritis - right kidney infection with fever, pyuria 2, 7
• Renal abscess or mass 2

Gastrointestinal Causes

• Peptic ulcer disease - particularly duodenal ulcers 2, 7
• Gastritis or duodenitis 7
• Hepatic flexure colitis 2
• Right colonic diverticulitis 2
• Inflammatory bowel disease affecting right colon 2
• Intestinal obstruction 2

Adrenal Causes

• Adrenal hemorrhage or mass 2

Vascular Causes

• Hepatic artery aneurysm or dissection 2
• Mesenteric ischemia 7

Thoracic Causes

• Right lower lobe pneumonia - referred pain to RUQ 2, 7
• Pulmonary embolism - particularly affecting right lower lobe 7
• Pleural effusion 2

Musculoskeletal Causes

• Rib fracture or costochondritis 7
• Abdominal wall muscle strain 7

Gynecologic Causes (in women of reproductive age)

• Ectopic pregnancy - requires pregnancy test before imaging 4, 5
• Ovarian torsion or cyst 7
• Pelvic inflammatory disease 7

Critical "Can't Miss" Diagnoses

Several life-threatening conditions must be actively excluded when evaluating RUQ pain, as they require urgent intervention and can present atypically: 7

• Perforated viscus (duodenal ulcer, gallbladder perforation)
• Acute myocardial infarction - inferior wall MI can present as RUQ pain
• Ruptured ectopic pregnancy
• Ruptured hepatic abscess or tumor
• Mesenteric ischemia
• Pulmonary embolism

Common Pitfall

Do not assume all RUQ pain is biliary in origin. More than one-third of patients with acute RUQ pain do not have acute cholecystitis, and systematic evaluation of alternative organ systems is essential to avoid missed diagnoses. 2, 3 The broad differential requires integration of clinical presentation, laboratory findings, and appropriate imaging to establish the correct diagnosis and guide management.