Differential Diagnosis for RUQ Pain

The differential diagnosis for right upper quadrant (RUQ) pain can be extensive, involving various organs and systems. Here's a categorized approach to help in diagnosing the cause of RUQ pain:

• Single Most Likely Diagnosis

  • Gallbladder Disease (Cholecystitis or Cholelithiasis): This is often the first consideration for RUQ pain due to the high prevalence of gallstones and the frequency of gallbladder inflammation. Symptoms such as pain after eating fatty foods, nausea, and vomiting support this diagnosis.

• Other Likely Diagnoses

  • Peptic Ulcer Disease: Both gastric and duodenal ulcers can cause RUQ pain, especially if the pain is related to eating or is worse at night.
  • Hepatitis: Inflammation of the liver can cause RUQ pain, and it's essential to consider viral, alcoholic, or autoimmune causes.
  • Pyelonephritis or Kidney Stones: While these conditions typically cause flank pain, they can sometimes radiate to the RUQ, especially if the right kidney is involved.
  • Pneumonia (Right Lower Lobe): Referred pain from the right lower lobe of the lung can sometimes be perceived in the RUQ due to the shared innervation of the diaphragm.

• Do Not Miss Diagnoses

  • Appendicitis (with an Atypical Presentation): Although appendicitis typically presents with right lower quadrant pain, an atypically located appendix can cause pain in the RUQ.
  • Myocardial Infarction: Cardiac ischemia can sometimes cause referred pain in the RUQ, especially if there is involvement of the right coronary artery.
  • Pulmonary Embolism: While more commonly associated with pleuritic chest pain, a pulmonary embolism can occasionally cause RUQ pain if the embolism affects the lung periphery near the diaphragm.
  • Hepatic Abscess or Infarct: These conditions can present with RUQ pain and are critical to diagnose due to their potential for severe morbidity and mortality.

• Rare Diagnoses

  • Fitz-Hugh-Curtis Syndrome: A rare condition characterized by perihepatitis due to gonococcal or chlamydial infection, causing RUQ pain.
  • Hepatocellular Carcinoma: A primary liver cancer that can cause RUQ pain, especially in patients with underlying liver disease.
  • Intra-abdominal Lymphoma: Lymphoma involving the liver, spleen, or abdominal lymph nodes can cause RUQ pain among other symptoms.
  • Diaphragmatic Hernia: A rare condition where abdominal contents herniate through the diaphragm, potentially causing RUQ pain and respiratory symptoms.

Each of these diagnoses has a unique set of clinical features, laboratory findings, and imaging characteristics that can help guide the diagnostic process. A thorough history, physical examination, and judicious use of diagnostic tests are essential for accurately diagnosing the cause of RUQ pain.