ABSTRACT
Most spinal surgery causes minimal blood loss. There is not usually much bleeding from within the spinal canal, especially if patients are correctly positioned to avoid pressure on the abdomen. Disc surgery and spinal decompression does not usually require a blood transfusion. There is more bleeding during a spinal fusion when the cortex is removed from the posterior bony elements. Taking a bone graft from the pelvis may also cause sufficient blood loss to require transfusion. More serious bleeding is unusual, but sometimes the vessels external to the spine are in the operation field. There are one or two areas of potential danger.
