Pre-operative CBC reflex testing prior to cardiac surgery identifies treatable causes of anemia

Abstract Blood transfusion during or after cardiac surgery has been linked to poor patient outcomes. It is therefore desirable to optimize hemoglobin status by identifying and treating anemia pre-operatively. In order to identify reversible causes of anemia efficiently in this patient cohort, we implemented a reflex order for our institution’s cardiothoracic surgery center, to be ordered for patients undergoing assessment for cardiac surgery. When ordered, complete blood count (CBC) results with a hemoglobin (Hgb) of less than 13 g/dL reflex automatically to the following laboratory tests: iron profile, ferritin, vitamin B12, and reticulocyte count. Methods The purpose of our study was to investigate the impact of this reflex order over the initial 6 months of implementation. Test results and patient notes were extracted from the electronic health record and analyzed. Results Over six months, the order was placed 99 times (median Hgb 13.4 g/dL), with 36 (36%) triggering the reflex (Hgb < 13 g/dL). Of these 36 patients, 19 were women and 17 were men, and the cohort had a median age of 69 years. The median Hgb was 11.9 g/dL, ranging from 7.1 to 12.9 g/dL, with a median mean corpuscular volume (MCV) of 89.6 fl. The median Hgb differed by sex: 11.6 g/dL for men, 12.2 g/dL for women. Of these 36 patients, 16 had signs of iron deficiency anemia (IDA) based on laboratory results (below reference interval for iron, transferrin saturation, or ferritin), and two patients were found with vitamin B12 below the reference interval. Chart review demonstrated that 13 of the 36 patients underwent follow-up after reflex laboratory tests resulted, defined as a new diagnosis, new treatment, and/or new consult addressing the patient’s anemia. Five of these patients were given a new diagnosis of IDA, all of which were started on iron therapy. Three patients were transfused packed red blood cells prior to surgery; one was started on vitamin B12 supplementation; two had consults placed to address anemia; and two were given a new diagnosis of unspecified anemia. Conclusion Pre-operative CBC reflex testing facilitates the efficient and timely identification of reversible causes of anemia in patients undergoing diagnostic workup prior to cardiac surgery, while avoiding unnecessary panel testing in non-anemic patients.