Collateral Damage: Ruptured Peripancreatic Pseudoaneurysm Associated With Severe Celiac Artery Stenosis From Median Arcuate Ligament Compression.

Median arcuate ligament syndrome (MALS) results from compression of the celiac artery by the median arcuate ligament and is often asymptomatic or associated with chronic postprandial abdominal pain. Rarely, severe celiac artery stenosis can lead to increased collateral flow through the pancreaticoduodenal arcade and life-threatening hemorrhagic complications. We report the case of a 57-year-old woman with no history of pancreatitis, trauma, or abdominal surgery who presented with acute abdominal pain and was found to have a ruptured peripancreatic pseudoaneurysm arising from a celiac-superior mesenteric artery (SMA) collateral vessel. Computed tomography angiography (CTA) demonstrated severe proximal celiac artery stenosis with a hook-shaped narrowing, with the collateral vessel arising from the pancreaticoduodenal arcade, suggesting MALS. After an unsuccessful initial angiographic attempt, repeat intervention required direct percutaneous access, the use of thrombin injection to control active extravasation, and coil embolization of the pseudoaneurysm's inflow and outflow vessels. Her course was complicated by hemorrhagic shock, respiratory failure, and pulseless electrical activity arrest with return of spontaneous circulation. This case highlights an unusual life-threatening presentation of suspected MALS-related collateral vessel injury.