Utility of Routine Preoperative Laboratory Testing for Low-risk Patients in Ambulatory Gynecologic Surgery

Abstract

Study objectives: To examine the current use of routine preoperative laboratory testing in low-risk patients undergoing ambulatory gynecologic surgery and to determine if such testing affects surgical outcomes.

Design: The American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was queried for ambulatory gynecologic surgeries between 2015 and 2018. Low-risk patients included in this study were defined as being American Society of Anesthesiologists class 1 or 2. The rate of preoperative laboratory testing before ambulatory gynecologic surgery in low-risk patients was determined and factors associated with testing including patient characteristics and comorbidities were evaluated. NSQIP-defined complications were compared between those with and without preoperative laboratory testing. Preoperative laboratory testing was defined as chemistry, hematology, coagulation, or liver function studies obtained within 30 days preoperatively.

Setting: National health systems that participate in the NSQIP.

Patients: There were 19 855 patients who underwent an ambulatory gynecologic procedure.

Interventions: Preoperative laboratory testing in low-risk patients before ambulatory gynecologic surgery.

Measurements and main results: Of the 19 855 patients studied, 14 258 (71.8%) received preoperative laboratory testing. Statistically significant differences were seen between patients who underwent preoperative testing and patients who did not. The most frequent preoperative test was a complete blood cell count (70.4%). Among patients who received preoperative testing, 4053 (28.4%) had at least 1 abnormal result. No statistically significant difference was seen in overall postoperative complication rate when comparing patients who received preoperative laboratory testing with those who did not (2.5% vs 2.2%, p = .30). Specifically, no statistically significant difference was seen among wound complications (1.0% vs 1.0%, p = .78), major complications (1.0% vs 0.8%, p = .11), unplanned return to the operating room (0.1% vs 0.2%, p = .40), unplanned readmission (0.7% vs 0.5%, p = .10), or overall morbidity (2.1% vs 1.9%, p = .38). Chi-square analyses were performed to compare categoric variables. Continuous variables were compared using unpaired t tests.

Conclusion: This large study using a reputable national database revealed that despite updated evidence-based guidelines that recommend against the practice, preoperative laboratory testing continues to be performed for most low-risk patients undergoing ambulatory gynecologic surgery. This study also further supports current guidelines in demonstrating no difference in surgical outcomes between low-risk patients who did and did not receive preoperative laboratory testing. Preoperative laboratory testing practices for low-risk patients undergoing ambulatory gynecologic surgery do not follow current evidence-based guidelines and should be re-evaluated.

Keywords: Gynecology; NSQIP; Preoperative evaluation; Surgical complications; Surgical outcomes.