lumbar subarachnoid peritoneostomy, a surgical procedure to drain cerebrospinal fluid in hydrocephalus, usually in the newborn. It spares the kidney but is a slightly less effective method than a lumbar subarachnoid ureterostomy. The procedure may be used when a temporary shunt is needed. A lumbar laminectomy is performed, and then a polyethylene tube is passed from the subarachnoid space around the flank and into the peritoneum. This procedure is performed to correct a communicating type of hydrocephalus.
