Intraoperative echocardiography of a dislodged Bjork-Shiley mitral valve disc. The successful management of a patient who suffered an outlet strut fracture of a Bjork-Shiley 60-degree convexo-concave mitral valve prosthesis is reported. Emergency operation was life-saving. Preoperative echocardiography assisted in making a prompt diagnosis, and intraoperative echocardiography allowed the detection and removal of the dislodged disc from the left ventricle at the time of the operation. The role of intraoperative echocardiography in the diagnosis of prosthetic strut fracture is emphasized. 