Septic arthritis of the hip joint: sonographic and CT findings

Two patients with acute bacterial arthritis of the hip joint were suspected clinically to have a psoas abscess. For this reason a computed tomographic scan of the abdomen and pelvis (two patients) and ultrasonography (one patient) were requested. These scans showed no evidence of an abscess in the abdominal cavity nor retroperitoneum but did demonstrate a hip joint effusion which was compatible with septic arthritis.