Fig. 1.

The distribution of diagnoses in patients undergoing instrumented fusion with a diagnosis of spinal stenosis (SS), degenerative spondylolisthesis (DS), or herniated nucleus pulposus (HNP) is shown. There was no difference in the distribution of diagnoses among patients who predonated blood compared with those who did not predonate blood for spinal fusion surgery (χ² = 3.91; p = 0.14). The majority of patients undergoing fusion were diagnosed with either herniated nucleus pulposus or degenerative spondylolisthesis.