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.