Ultrasonic signs of pelvic osteomyelitis in children.

The ultrasonic findings were reviewed in 13 children in whom pelvic osteomyelitis was diagnosed by a positive 99mtechnetium methylene diphosphonate (MDP) bone scan in conjunction with clinical and laboratory features of osteomyelitis. All patients presented with pain in the region of the hip joint. In six patients the ultrasound study was confined to the hip joint, and all six had normal findings. In seven patients the ultrasound study was extended to include the pelvis. Deep soft tissue swelling was demonstrated in six of these, including a periosseous abscess in one case. Ultrasonography was negative in one patient with a 5-week history, whose pelvic osteomyelitis was resolving at the time of the ultrasound study. Oedema of the obturator internus and externus muscles was observed in osteomyelitis affecting the pubis and ischium, and of the iliacus and/or the gluteus medius muscle in osteomyelitis of the ilium. In children presenting with hip pain who have a normal hip ultrasound study, extension of the ultrasound examination to include these four pelvic muscles may help to identify and document the progression of acute pelvic osteomyelitis.