Hemolytic Anemia Caused by Iatrogenic Arteriovenous Iliac Fistula and Successfully Treated by Endovascular Stent-Graft Placement

Abstract

Hemolytic Anemia Caused by Iatrogenic Arteriovenous Iliac Fistula and Successfully Treated by Endovascular Stent-Graft Placement A 33-year-old man was admitted to our hospital for investigation and treatment of lower back pain. MRI of the lumbar spine revealed degenerative change and significant disk protrusion at the L5–S1 level, which was treated by lumbar diskectomy and laminectomy. Postoperatively, the patient developed back pain that was managed conservatively, and he was discharged. He was readmitted 3 months later with lethargy and persisting back discomfort. Physical examination was unremarkable. Laboratory investigations revealed anemia with elevated reticulocytes and lactate dehydrogenase (LDH) with reduced serum haptoglobins, consistent with hemolytic anemia from intravascular hemolysis. CT scans revealed indirect evidence of an arteriovenous fistula with opacification of a distended inferior vena cava in the arterial phase (Fig. 1A). A conventional angiogram confirmed the fistula between the right common iliac artery and left common iliac vein (Fig. 1B). The fistula developed secondary to the previous spinal surgery because of inadvertent trauma to the iliac vessels, and the rapid flow within the fistula resulted in hemolytic anemia. The fistula was subsequently treated with a covered stent-graft (Fig. 1C) with successful resolution of the patient’s hematologic parameters. The patient was discharged and remains well. Hemolytic anemias are generally classified into intravascular and extravascular hemolysis. In this case, the hemolytic anemia was intravascular and related to destruction of erythrocytes from high flow through the iliac fistula. Fistulas usually develop as a result of inflammation or trauma to the vessel or surrounding tissue. Trauma to the iliac vessels occurred inadvertently during surgery in this case. Vascular injury during spinal surgery is a known but unusual complication reported to occur with an incidence of 0.017% [1]. Retroperitoneal hemorrhage is well documented, but fistula formation is rare. The precise incidence of this complication is unknown, but one series reported arteriovenous fistula in 5 of 3,500 cases [2]. Previously, conventional angiography was necessary to make the diagnosis of a fistula; however, CT is now performed in the initial assessment of such patients [3]. CT findings include early filling and distention of the venous system and direct visualization of the fistula. Until recently, open surgical repair was the only treatment, and it had a significant operative mortality. In recent years, however, covered stent-graft technology has allowed for many fistulas of this kind to be treated in a minimally invasive fashion [4]. In the case we have presented, a covered stent-graft was successful in eliminating the iliac arteriovenous fistula and, thus, the patient’s hemolysis.