The Doppler pulsatility index as a screening test for blocked ventriculo-peritoneal shunts.

Doppler ultrasound studies have demonstrated a raised Gosling pulsatility and Pourcelot resistance index in untreated hydrocephalus. The application of transcranial Doppler ultrasound to the diagnosis of blocked ventriculoperitoneal shunts was studied by comparing the Gosling pulsatility indices of 63 children with symptoms of shunt malfunction with a reference range derived from 248 asymptomatic shunted children. An abnormally raised pulsatility index predicted a blocked shunt with a sensitivity of 56% and a specificity of 97%. The pulsatility index correlated with intracranial pressure in patients with confirmed shunt blockage.