Challenging surgical dogma: are routine postoperative day 1 laboratory tests necessary after bariatric operations?

Background: Postoperative day (POD) 1 laboratory tests are routinely ordered after bariatric operations.Objectives: Determine how often these laboratory tests are abnormal and whether they represent value-added care.Setting: Academic medical center, United States.Methods: Patients undergoing bariatric operations for obesity and complications from prior bariatric surgery from 1 January 2011 to 12 December 2020 at a single institution were identified. Patients with POD 1 hemoglobin, potassium, creatinine, or glucose serum laboratory tests obtained before 08:00 on POD 1 were reviewed. Laboratory-specific exclusion criteria were applied. Abnormal laboratory test results were a hemoglobin < 8.0 g/dL or a hemoglobin drop of > 3.0 g/dL; a potassium < 3.5 mmol/L (hypokalemia), 5.5-5.9 mmol/L (mild hyperkalemia), or > 6.0 mmol/L (severe hyperkalemia); a creatinine increase of 0.3 g/dL or 1.5X the preoperative value (acute kidney injury); and a glucose > 180 mg/ dL (hyperglycemia). Intervention for abnormal hemoglobin, potassium, and glucose was also assessed.Results: Of 2090 patients who underwent bariatric operations, 1969 met inclusion criteria for hemoglobin analysis, 1223 for potassium analysis, 1446 for creatinine analysis, and 563 for glucose analysis. Only 0.2% (n = 4) of patients had a hemoglobin < 8.0 g/dL< and only 3.1% (n = 62) had a > 3.0 g/dL hemoglobin drop. Potassium was abnormal in 2.8% of patients (n = 34 total). An acute kidney injury was diagnosed in 1.8% (n = 26) of patients. Hyperglycemia was identified in 2.1% (n = 12) of patients. Of 5227 laboratory test values, only 1.5% were abnormal. Further, of laboratory tests analyzed for intervention (n = 3781), only 14 (0.4%) were actively acted upon.Conclusions: Routine POD 1 laboratory tests after bariatric operations seem to be a continuation of a surgical tradition rather than a clinically valuable tool. POD 1 laboratory tests should be ordered based on specific patient co-morbidities and clinical criteria. (Surg Obes Relat Dis 2022;18:1261- 1268.) (c) 2022 American Society for Metabolic and Bariatric Surgery. Published by Elsevier Inc. All rights reserved.

Automated summary

This study investigated the frequency and clinical value of routine postoperative day 1 laboratory tests after bariatric operations. The findings showed that the abnormality rate of these tests was very low, and only a small percentage of abnormal results required intervention. The study suggests that postoperative day 1 laboratory tests should be ordered based on specific patient comorbidities and clinical criteria.