External ventricular drain (EVD)

An External ventricular drain (EVD) is a temporary drainage of excess cerebrospinal fluid (CSF) from the lateral ventricles of the brain into an external collection bag. 

The surgeon plans a burrhole (small bone opening) that will allow the passage of a sterile tube into the brain ventricles. The EVD system drains the CSF into a collection bag. The drainage amount and rate depends on the height at which the EVD system is placed relative to the patient’s anatomy.