Differential Diagnosis for Left Flank Pain

The differential diagnosis for left flank pain can be categorized into several groups based on the likelihood and potential severity of the conditions.

• Single Most Likely Diagnosis

  • Nephrolithiasis (Kidney Stones): This is often the most common cause of acute flank pain, typically presenting with severe, colicky pain that may radiate to the groin. The pain is usually accompanied by nausea, vomiting, and sometimes hematuria.

• Other Likely Diagnoses

  • Pyelonephritis: An infection of the kidney, which can cause flank pain, fever, and other urinary symptoms. It's more common in women and those with urinary tract abnormalities.
  • Musculoskeletal Strain: Overuse or injury to the muscles in the flank area can cause significant pain, especially if there's a history of heavy lifting or strenuous activity.
  • Diverticulitis: Inflammation of a diverticulum in the colon, which can cause left lower quadrant pain that may be perceived as flank pain, especially if the diverticulum is located near the spleen or kidney.

• Do Not Miss Diagnoses

  • Abdominal Aortic Aneurysm: Although less common, a ruptured abdominal aortic aneurysm can present with severe back or flank pain and is a medical emergency.
  • Pulmonary Embolism: In some cases, a pulmonary embolism can cause referred pain to the flank area, especially if the embolism is large and affects the lower parts of the lung.
  • Splenetic Rupture or Infarct: These conditions can cause severe left upper quadrant pain that may radiate to the flank and are emergencies, especially in patients with a history of trauma or spleen diseases.

• Rare Diagnoses

  • Pancreatitis: While more commonly associated with mid-abdominal pain, pancreatitis can cause flank pain, especially if the pancreatic tail is involved.
  • Retroperitoneal Fibrosis: A rare condition characterized by the proliferation of fibrous tissue in the retroperitoneum, which can encase and obstruct structures like the ureters, leading to flank pain.
  • Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic hypertension and may present with flank pain due to the location of the tumor.

Each of these diagnoses has distinct characteristics and risk factors, and a thorough history, physical examination, and diagnostic testing are crucial for accurate diagnosis and appropriate management.