1. Active Bleeding.
2. Acquired or inherited bleeding disorders.
3. Formally anti-coagulated (e.g. INR>2).
4. Acute stroke.
5. Platelets <75.
6. BP > 230/120.
7. LP/Epidural/Spinal anaesthesia within previous 4 or next 12 hours.
8. Other high risk procedures anticipated in next 12 hours.