Introduction: Estimates made from national inpatient databases estimate that approximately 200,000 lumbar fusions are performed annually in the United States alone. Surgeons commonly order hematologic studies to rule out postoperative anemia. However no authors have analyzed the utility of these labs following lumbar fusions.

Methods: A retrospective analysis of all lumbar fusion procedures performed over a 10-year period from 2002-2012 at a single institution by 3 spine surgeons was performed. Inclusion criteria included instrumented and non-instrumented lumbar fusions performed for any etiology with no more than 1 thoracic or 1 sacral level included in the fusion construct. Data was acquired on pre- and post-operative hematologic lab results including the hematocrit, platelet count and INR as well as patient factors such as age, gender, number of levels operated on, indication for surgery, intraoperative blood loss. Multivariate logistic regression was performed to determine correlation to postoperative transfusion requirement or readmission within 1 month of discharge for anemia or transfusion.

Results: 490 patients undergoing lumbar fusion were identified. Mean number of levels fused was 1.4. 25 patients (5.1%) required postoperative transfusion. No patients required readmission for anemia or transfusion. Multivariate logistic regression discovered correlations between reduced preoperative hematocrit, reduced preoperative platelet count and increased intraoperative blood loss as predictive of postoperative transfusion requirement. No correlation was found between postoperative transfusion requirement and number of levels operated on, or indication for operation. Intraoperative blood loss >1000 cc had an odds ratio (OR) of 8.9 (p<0.05), and preoperative hematocrit <35 had an OR of 4.3 (p<0.05) of requiring a postoperative transfusion.

Conclusions: Postoperative anemia requiring transfusion following lumbar fusion is rare. Low preoperative hematocrit and intraoperative blood loss was predictive of increased risk of transfusion requirement. These factors can be used to determine when postoperative hematologic labs may be useful in the management of this patient population.

Patient Care: Routine postoperative studies often do not change patient management. By using a data/evidence based algorithm for utilization of postoperative labs, we hope to contain costs while providing the same quality of care.

Learning Objectives: By the conclusion of this session, participants should be able to describe the importance of cost-effective utilization of postoperative hematologic studies and be aware of evidence based criteria for postoperative management.

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