Differential Diagnosis

The patient's symptoms of right upper quadrant (RUQ) pain, nausea, possible fever, and off-and-on diarrhea for about a week can be approached by considering the following categories:

• Single Most Likely Diagnosis

  • Gallbladder Disease (Cholecystitis or Cholelithiasis): The patient's RUQ pain, nausea, and possible fever are classic symptoms for gallbladder disease. The pain often worsens over time and can be accompanied by nausea and vomiting. Given the location of the pain and the associated symptoms, this is a highly plausible diagnosis.

• Other Likely Diagnoses

  • Gastroenteritis: The combination of diarrhea, nausea, and possible fever could suggest a gastrointestinal infection. The fact that the diarrhea has been present for about a week supports this possibility.
  • Peptic Ulcer Disease: RUQ pain and nausea can also be symptoms of peptic ulcer disease. The pain can be exacerbated by food or improved by antacids, but these specifics are not mentioned.
  • Hepatitis: Although less common, hepatitis can present with RUQ pain due to liver inflammation, along with nausea and possibly fever. The absence of jaundice does not rule out hepatitis.

• Do Not Miss Diagnoses

  • Appendicitis: Although the pain is in the RUQ, appendicitis typically starts near the belly button and then moves to the lower right abdomen. However, it's crucial not to miss this diagnosis, as a ruptured appendix can be life-threatening. The presence of diarrhea and possible fever slightly increases the concern for appendicitis, despite the atypical location of the pain.
  • Pneumonia: Right lower lobe pneumonia can cause referred pain to the RUQ, especially if the diaphragm is involved. The possible fever and nausea support this consideration.
  • Biliary Duct Obstruction: This condition can cause severe pain, jaundice, and fever. While jaundice is not mentioned, it's a critical diagnosis not to miss due to potential severe complications.

• Rare Diagnoses

  • Liver Abscess: A collection of pus in the liver can cause RUQ pain, fever, and nausea. It's less common but should be considered, especially if the patient has risk factors such as recent travel or immune compromise.
  • Pancreatitis: Although pancreatitis typically causes mid-abdominal pain radiating to the back, it can sometimes present with RUQ pain. The presence of nausea and possible fever, along with the severe nature of pancreatitis, warrants its inclusion in the differential diagnosis.