Differential Diagnosis for RUQ Pain

The patient presents with right upper quadrant (RUQ) pain, a history of appendectomy, positive Murphy sign, and symptoms aggravated by prolonged fasting. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis

  • Cholecystitis: The positive Murphy sign is highly suggestive of cholecystitis, especially in the context of RUQ pain. The aggravation of symptoms by prolonged fasting also points towards gallbladder pathology, as fasting can lead to gallbladder contraction and increased pressure, exacerbating pain.

• Other Likely Diagnoses

  • Cholelithiasis: Gallstones are a common cause of RUQ pain and could be related to the patient's symptoms, especially if they are obstructing the cystic duct, leading to cholecystitis.
  • Peptic Ulcer Disease: Although the patient does not report nausea or vomiting, peptic ulcers can cause RUQ pain and can be exacerbated by fasting, which increases gastric acid production.
  • Hepatitis: Viral or toxic hepatitis could present with RUQ pain, although the absence of nausea and vomiting makes this less likely.

• Do Not Miss Diagnoses

  • Hepatic Abscess: Although rare, a hepatic abscess can present with RUQ pain and could be life-threatening if not promptly diagnosed and treated.
  • Perforated Visculature (e.g., hepatic artery aneurysm): Any condition leading to perforation or rupture of vascular structures in the abdomen can cause severe pain and is immediately life-threatening.
  • Budd-Chiari Syndrome: Obstruction of the hepatic veins can cause RUQ pain, ascites, and potentially life-threatening complications if not recognized.

• Rare Diagnoses

  • Sphincter of Oddi Dysfunction: This condition can cause biliary-type pain and could be considered in patients with recurrent RUQ pain without evidence of gallstones or other obvious causes.
  • Intrahepatic Cholestasis: Conditions causing intrahepatic cholestasis, such as primary biliary cirrhosis, can present with RUQ pain, although they are less common and typically have other associated symptoms like pruritus.

Each of these diagnoses should be considered in the context of the patient's full clinical picture, including laboratory results and imaging studies, to determine the most appropriate diagnosis and treatment plan.