Radiographic imaging requirements following ventriculoperitoneal shunt procedures

The requirements for radiographic imaging of the ventricles after a ventricular shunt procedure are not well defined. At British Columbia's Children's Hospital, the standard protocol included an ultrasound examination or CT scan at 6-8 weeks postoperatively, and a delayed CT scan at 6 months to 2 years, with additional scans only if the patient had symptoms of shunt malfunction. This study was performed to determine if the delayed scan could be omitted without compromising patient care. The study comprised 86 children with ventriculoperitoneal shunt operations, who had early CT scans or ultrasound examinations less than 20 weeks postoperatively, delayed postoperative CT scans between 20 weeks and 2 years, and who were asymptomatic at the time of these radiographic studies. In 39 of the 86 patients a change in ventricular size occurred between the early and delayed imaging studies, and in these patients the delayed scan was felt to be required. In patients in whom the early imaging study was done at more than 12 weeks postoperatively, and probably in patients with small ventricles preoperatively, there was no added information gained by doing a delayed scan. It is concluded that a radiographic examination of ventricular size at 12 weeks after a shunt operation may provide an adequate baseline study. If the early postoperative radiographic study is done less than 12 weeks after surgery, we would advise that in asymptomatic patients, with the exception of patients with very small ventricles preoperatively, a CT scan be repeated at a later date to obtain an appropriate baseline assessment of ventricular size for the future.