Differential Diagnosis for Upper Abdominal Pain after Failed ERCP for Impacted CBD Stone

Single Most Likely Diagnosis

• Post ERCP Pancreatitis: This is the most likely cause of pain after a failed ERCP procedure. ERCP is known to have a risk of causing pancreatitis, especially if the procedure is difficult or if there are multiple attempts at cannulation or stone removal. The presence of upper abdominal pain and mild tenderness, despite unremarkable labs, could be indicative of mild pancreatitis.

Other Likely Diagnoses

• Cholangitis due to CBD stone: Although the labs are unremarkable, cholangitis is a possible cause of pain, especially if the stone is still obstructing the bile duct. However, the absence of significant laboratory abnormalities (such as elevated white blood cell count or liver function tests) makes this less likely.
• Acute on chronic cholecystitis: If the patient has a history of gallstones, it's possible that the current pain is related to cholecystitis, either as a new episode or exacerbation of chronic inflammation.

Do Not Miss Diagnoses

• Bleeding: Although less common, bleeding can occur after ERCP, either from the site of sphincterotomy or from the bile duct itself. It's crucial to consider this possibility, even if labs are initially unremarkable, as delayed presentation of bleeding can occur.
• Duodenal perforation: This is a serious complication of ERCP that requires prompt recognition and treatment. Even if the patient does not have peritoneal signs, a perforation can still cause significant pain and must be ruled out.

Rare Diagnoses

• Other rare complications of ERCP, such as retroperitoneal perforation or hemobilia, could also be considered but are less likely given the clinical presentation.
• Mirizzi syndrome (if the stone is causing obstruction of the bile duct by extrinsic compression from a gallstone in the cystic duct) could be a rare cause of ongoing pain but would typically be identified during the ERCP procedure.

Each of these diagnoses should be considered in the context of the patient's overall clinical picture, and further diagnostic testing or procedures may be necessary to determine the exact cause of the pain.