Psoas abscess as a complication of pyogenic sacroiliitis: report of a case.

A psoas abscess is, either primary or secondary, a rare entity for a general surgeon. Images by ultrasonography and computed tomography (CT) can help a general surgeon to make an accurate diagnosis when encountering the patient complaining of unilateral lower abdominal deep pain with fever. A case of pyogenic abscess of the psoas muscle as a result of sacroiliitis in a 22-year-old man is reported herein. The abdominal CT and magnetic resonance imaging scans demonstrated a large multilocular abscess extending along the iliopsoas muscle, and erosion and a widening of the left sacroiliac joint. The abscess was drained with an open surgical approach and the patient responded well to antibiotic therapy. Aggressive surgical and medical treatment is necessary in patients with psoas abscess to prevent complications.