Relationship between preoperative external ventricular drainage and preoperative rebleeding in aneurysmal subarachnoid hemorrhage: A meta-analysis

•Current evidence does not support that preop-EVD significantly increases the risk of rebleeding prior to aneurysm repair.•Patients with poorer clinical status on admission and aneurysms > 1 cm are at a higher risk of preop-rebleeding.•Patients with worse admission status are associated with higher risk of rebleeding and poorer prognosis.