Differential Diagnosis for Flank Pain

The following is a list of potential diagnoses for flank pain, categorized by likelihood and potential impact.

• Single most likely diagnosis

  • Nephrolithiasis (kidney stones): This is a common cause of flank pain, often accompanied by nausea, vomiting, and hematuria. The pain is typically severe and colicky, radiating from the flank to the groin.

• Other Likely diagnoses

  • Pyelonephritis: An infection of the kidney, which can cause flank pain, fever, and urinary symptoms such as dysuria and frequency.
  • Musculoskeletal strain: Overuse or injury to the muscles in the flank area can cause pain, especially if there is a history of heavy lifting or strenuous activity.
  • Urinary tract infection (UTI): While more commonly associated with lower urinary tract symptoms, upper UTIs can cause flank pain.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Renal infarction: A blockage of the renal arteries, which can cause severe flank pain and potentially lead to kidney damage or failure if not promptly treated.
  • AAA (Abdominal Aortic Aneurysm): Although more commonly associated with abdominal pain, a ruptured AAA can cause flank pain and is a medical emergency.
  • Sickle cell crisis: In patients with sickle cell disease, a crisis can cause severe pain, including flank pain, due to vaso-occlusion.

• Rare diagnoses

  • Renal cell carcinoma: A type of kidney cancer that can cause flank pain, although it is less common and typically presents with a palpable mass or hematuria.
  • Polycystic kidney disease (PKD): A genetic disorder characterized by the growth of numerous cysts filled with fluid in the kidneys, which can cause flank pain, although it is often asymptomatic until later stages.
  • Retroperitoneal fibrosis: A rare condition characterized by the proliferation of fibrous tissue in the retroperitoneum, which can cause flank pain and obstructive uropathy.