Preoperative Laboratory Test Utilization in Young, Healthy Patients Undergoing Outpatient Low-Risk Surgery

From the 2018 HVPAA National Conference

Joshua Tseng (Cedars-Sinai Medical Center), Tara Cohen (Cedars-Sinai Medical Center), Daniel Margulies (Cedars-Sinai Medical Center), Rodrigo Alban (Cedars-Sinai Medical Center)


The utility of preoperative laboratory (lab) testing in low-risk surgeries is widely questioned. Both the American Society of Anesthesiologists and National Institute of Health and Care Guidance in the UK recommend against routine preoperative tests for outpatient elective surgeries in patients with ASA class 1 or 2.


To assess utilization rates of preoperative lab testing for common elective, outpatient surgical procedures such as initial hernia repairs, breast mass excisions, and knee or shoulder arthroscopies.


Using the 2015 ACS-NSQIP database, we identified all patients from ages 16-50 who underwent an elective, outpatient surgery with ASA class 1 or 2. Patients undergoing initial hernia repairs, breast mass excisions, and arthroscopies were selected via specific CPT codes.  Variables obtained include patient demographics, comorbidities, preoperative lab results, and complication rates.  The number of comorbidities in each patient was tabulated. Comparisons between patients with preoperative labs and no preoperative labs were made with the student’s t-test and Pearson’s chi-squared test where appropriate.


A total of 38,157 patients undergoing elective, outpatient surgery were included in the study, with 16,525 undergoing hernia repair, 14,029 undergoing arthroscopy, and 7,603 undergoing breast mass excision. The majority of patients had no comorbidities (70.9%), while 25.4% had one, and 3.7% had two or more.  Overall utilization rates of CBC’s, BMP’s, and coagulation panels were 43.9%, 38.6%, and 8.9%, respectively.  Preoperative labs were obtained in 54.4% of hernia repairs, 35.3% of arthroscopies, and 53.6% of breast mass excisions.  Patients with preoperative labs were more likely to have comorbidities (35.1% vs 21.9%, p<.001), and the rates of preoperative lab testing increased in relation to the number of comorbidities.  Overall complication rate was 1.1%; of these complications, 64.0% were related to wound complications.  Patients with preoperative labs had higher rates of superficial surgical site infections and wound disruptions (0.7% vs 0.3%, p<.001 and 0.1% vs 0.0%, p=.009, respectively).  There was no difference in terms of postoperative bleeding or transfusions (0.1% vs 0.0%, p=.154).


Despite recommendations against routine preoperative tests in this population by multiple organizations, preoperative lab utilization rates for elective, outpatient, low-risk surgery in young, healthy patients remain high. Overall complication rates are low and mainly secondary to wound complications.

Implications for the Patient

Adhering to current guidelines for pre-op lab testing may lead to significant cost savings without affecting outcomes.

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