S2160 Bottomed Out: A Case of Hemorrhagic Shock Due to Rectal-Arterial Fistulization

INTRODUCTION: Lower gastrointestinal bleeding (LGIB) can present as a chronic, minor finding or as an acute, life-threatening event. Typical causes of LGIB include angiodysplasias, ischemia, diverticula, and neoplasms. Here, we present a rare case of life-threatening LGIB as a complication in a patient with a known history of colon cancer. CASE DESCRIPTION/METHODS: A 66-year-old male with a history of metastatic colon cancer who presented to the emergency department for hematochezia. The patient is status post partial colectomy, pelvic radiation, colostomy installation, and preserved rectum. Of note, the patient also has a history of chronic lower GI bleeding secondary to arterial-rectal fistulization, requiring left internal iliac artery coil embolization 1 year prior. On the day of presentation, the patient developed generalized weakness but was able to perform his daily activities. That afternoon, he developed massive, brisk bright red blood per rectum. Initial blood loss was estimated to be approximately 2 liters. Upon arrival to the emergency department, he was initiated on the massive transfusion protocol but quickly developed hemorrhagic shock with a mean arterial pressure 45, cool extremities, and altered mental status. With estimated blood loss of 4 liters, he was intubated and taken for emergent interventional pelvic angiography. Angiography demonstrated arterial-rectal fistula with massive extravasation into the rectum from a newly eroded stump of the previous coil embolization in the left internal iliac artery. Source control required covered stent placement into the left common iliac artery, occluding the internal iliac artery. Patient was brought to the intensive care unit where resuscitative measures were continued. Within the two hours of patient's hospital stay, he received 12 units of packed red blood cells, 5 units fresh frozen plasma, 2 units cryoprecipitate, 3 units of platelets, and 3 liters of lactated ringers. The rest of the patient's hospital stay was uneventful. DISCUSSION: Although rare, patients with a known history of pelvic neoplasm, pelvic surgery, and pelvic radiation are at increased risk for massive LGIB secondary to fistula formation into neighboring vasculature. As demonstrated in this case, arterial fistulization can quickly become fatal if source control is not obtained immediately. This case demonstrates the importance of keeping arterial fistulization as a differential in patients with acute LGIB.Figure 1.: Pelvic angiography demonstrating left internal iliac artery-rectal fistula with massive extravasation into the rectum.