What are the differentials to rule out in a patient presenting with right upper quadrant abdominal pain?

Differential Diagnoses for Right Upper Quadrant Abdominal Pain

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

Biliary and Gallbladder Causes

Acute cholecystitis is the most common diagnosis to exclude in patients presenting with acute RUQ pain, characterized by gallbladder inflammation with gallstones, fever, leukocytosis, and positive Murphy's sign. 2, 1 Ultrasound findings include gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy's sign. 1

Biliary colic presents as episodic severe pain from gallstones causing transient cystic duct obstruction, typically radiating to the right shoulder or back, without fever or inflammatory markers. 1

Choledocholithiasis (common bile duct stones) causes obstruction with elevated liver enzymes, particularly alkaline phosphatase and bilirubin, and may present with colicky pain radiating to the back. 3, 1 This occurs in 5-15% of post-cholecystectomy patients but can occur in any patient with gallstones. 3

Acute cholangitis requires the triad of jaundice, fever/chills, and RUQ pain, plus laboratory evidence of biliary stasis and imaging showing biliary dilatation—this is a surgical emergency. 1

Chronic cholecystitis and biliary dyskinesia present with recurrent RUQ pain mimicking acute disease but with less dramatic inflammatory findings. 2

Hepatic Causes

Hepatic abscess (pyogenic or amebic) presents with fever, RUQ pain, and elevated inflammatory markers—ruptured hepatic abscess is a life-threatening emergency requiring urgent intervention. 1

Hepatitis (viral, alcoholic, or drug-induced) causes RUQ pain with markedly elevated transaminases (ALT/AST), often with jaundice. 1

Hepatic masses or tumors including hepatocellular carcinoma or metastases can cause RUQ pain—rupture is a critical diagnosis requiring immediate recognition. 1

Gastrointestinal Causes

Peptic ulcer disease (gastric or duodenal) can mimic acute cholecystitis with epigastric or RUQ pain, particularly perforated ulcers which present with peritoneal signs. 2

Pancreatitis presents with epigastric pain radiating to the back, elevated lipase/amylase, and can extend to involve the RUQ. 2

Gastroenteritis causes diffuse abdominal pain with nausea, vomiting, and diarrhea but can initially present with RUQ predominance. 2

Bowel obstruction (small or large bowel) can present with RUQ pain, particularly if the hepatic flexure is involved, with associated nausea, vomiting, and obstipation. 2

Acute appendicitis can rarely present with RUQ pain, particularly in cases of retrocecal appendix or when located within an inguinal hernia (Amyand's hernia), and synchronous acute appendicitis with acute cholecystitis has been reported. 4, 5

Epiploic appendagitis is a rare self-limiting condition caused by inflammation of epiploic appendages that can mimic acute cholecystitis, diagnosed on CT scan. 6

Pulmonary Causes

Pneumonia (right lower lobe) can present with RUQ pain due to diaphragmatic irritation, with associated cough, fever, and respiratory symptoms. 1

Pulmonary embolism is a critical diagnosis that can present with pleuritic chest pain extending to the RUQ, requiring urgent evaluation. 1

Renal Causes

Pyelonephritis (right-sided) presents with flank pain that may extend to the RUQ, with fever, dysuria, and pyuria. 1

Nephrolithiasis (right kidney or ureter) causes colicky flank pain radiating anteriorly to the RUQ, with hematuria. 1

Gynecologic Causes (in Women of Reproductive Age)

Ectopic pregnancy is a life-threatening condition requiring a pregnancy test before imaging in all women of reproductive age—ruptured ectopic pregnancy requires urgent surgical intervention. 1

Ovarian torsion or ruptured ovarian cyst can present with RUQ pain if the right ovary is involved. 1

Vascular Causes

Mesenteric ischemia is a life-threatening condition presenting with severe abdominal pain out of proportion to physical examination findings, requiring urgent intervention. 1

Post-Surgical Causes

Bile duct injury or stricture can occur as a complication of cholecystectomy, presenting with intermittent obstruction and RUQ pain. 3

Biloma (bile collection) following cholecystectomy or hepatobiliary surgery presents with persistent RUQ pain and can be identified on ultrasound or CT. 3

Sphincter of Oddi dysfunction causes recurrent RUQ pain mimicking chronic cholecystitis in post-cholecystectomy patients. 3

Critical "Can't Miss" Diagnoses

The following require immediate recognition and intervention:

• Ruptured ectopic pregnancy 1
• Perforated gallbladder with peritonitis 1
• Ruptured hepatic abscess or tumor 1
• Mesenteric ischemia 1
• Pulmonary embolism 1
• Acute cholangitis 1

Diagnostic Approach

Ultrasound is the first-line imaging study for RUQ pain evaluation, rated 9/9 (usually appropriate) by the American College of Radiology. 7, 1 It should be performed without delay to evaluate for gallstones (96% accuracy), gallbladder wall thickening, pericholecystic fluid, bile duct dilatation, and hepatic abnormalities. 7

If ultrasound is negative or equivocal and biliary pathology remains suspected, MRCP is the preferred advanced imaging modality with 85-100% sensitivity and 90% specificity for detecting choledocholithiasis and biliary obstruction. 7 MRCP provides comprehensive evaluation of the entire hepatobiliary system and is superior to CT for assessing suspected biliary sources of RUQ pain. 7

CT with IV contrast should be reserved for critically ill patients with peritoneal signs, suspected complications beyond simple biliary pathology, or when alternative diagnoses are being considered. 7, 1