If clinically indicated, the external ventricular drainage cerebrospinal fluid collection system may be accessed by physicians, and in some institutions, by nurses, withdrawing CSF for the purposes of cultures and/or obtaining malignant cells, or to instill medications 1) 2) 3).
Spinal fluid samples are generally obtained through the proximal port (closest to the head) of the EVD collecting system and are performed using a strict sterile technique due to the risk of infection 4).
Samples should not be collected from the external ventricular drainage cerebrospinal fluid collection bag due to the rapid degradation of cellular components. Though samples can be drawn from the distal port, white cell counts and cultures are often not accurate 5).
When drawing the sample, aspiration should be very slow (no more than 1 ml/min) and if any resistance is met, the procedure should be aborted and a physician should be notified immediately. When medications are introduced into the EVD, such as tissue plasminogen activator for intraventricular hemorrhage 6) or antibiotics for ventriculitis 7) the EVD should be clamped for 1 h after administration.