Ruptured Internal Iliac Artery Aneurysm Presenting as Syncope and Left-Sided Abdominal Pain: A Rare Cause of Collapse in the Emergency Department.

Ruptured internal iliac artery aneurysm (IIAA) is a rare but life-threatening vascular emergency that can mimic gastrointestinal or urological conditions. A 61-year-old man presented to the emergency department with sudden, severe left iliac fossa and groin pain followed by two episodes of collapse. On arrival, he was hypotensive (88/68 mmHg) and pale, with left-sided abdominal tenderness but no pulsatile mass. The bedside ultrasound was unremarkable, but his condition deteriorated despite fluid resuscitation. Laboratory tests showed low hemoglobin and raised lactate. Contrast-enhanced computed tomography (CT) revealed a ruptured left IIAA measuring 7 × 6.7 cm with extensive retroperitoneal hemorrhage. The patient underwent urgent endovascular embolization and stent placement, with successful aneurysm exclusion and recovery. This case emphasizes the need to consider vascular causes in patients presenting with collapse and lower abdominal pain, even when initial imaging is inconclusive. Early CT imaging and prompt endovascular management are crucial for survival in such rare presentations.