Preoperative Type and Screen Before General Thoracic Surgery: A Nomogram to Reduce Unnecessary Tests

Background: A preoperative type and screen (T&S) is traditionally routinely obtained before noncardiac thoracic surgery; however an intraoperative blood transfusion is rare. This practice is overly cautious and expensive. Methods: We included adult patients undergoing major thoracic surgery at the Mayo Clinic from 2007 to 2016. Patients receiving a T&S blood test ≤72 hours of surgery was the main exposure. We randomly split the cohort into derivation and validation datasets. We used multiple logistic regression to create a parsimonious nomogram predicting the need for a T&S in relation to the likelihood of intraoperative blood transfusion. We validated the nomogram in terms of discrimination, calibration, and negative predictive value. Results: Of 6280 patients 46.1% had a preoperative T&S, but only 7.1% received intraoperative transfusions. The derivation dataset had 4196 patients. Patients who had a T&S were more likely to have baseline hemoglobin level <10 g/dL (7.9% vs 3.6%, P < .001) and less likely to have minimally invasive operations (36.1% vs 43.5%, P < .001) but were otherwise similar in baseline age and comorbidities. A transfusion threshold of 5% was selected a priori. The nomogram included age, planned operation, approach, body mass index, and preoperative hemoglobin. The nomogram was validated with a c-statistic of 86% and a negative predictive value of 97.9%. Patients who needed a blood transfusion but who did not have a preoperative T&S did not have a higher rate of mortality (P = .121). Conclusions: An intraoperative blood transfusion during major thoracic surgery is a rare event. Patient who required transfusion but did not have a T&S did not have worse outcomes. A simple nomogram can aid in the selective use of T&S orders preoperatively.