The value of an ultrasonic flowmeter in assessing the function of CSF shunts.

In 113 children suspected of having CSF shunt dysfunction, the shunts were examined with a Doppler ultrasound flowmeter on 203 occasions. Shunt patency or blockage was correctly diagnosed in 90% of cases. There were 5% false-positive and 5% false-negative tests. Certain pitfalls of the investigation and its future applications are discussed.