Post-operative Hemoglobin Trends for Patients Undergoing Bariatric Surgery: A Retrospective Observational Study

BACKGROUND: Prevalence of same day bariatric surgery programs is rising. While observational studies suggest same day outcomes are similar to inpatient programs, the ability to detect early post-operative bleeding in same day patients is uncertain. We compared hemoglobin values between patients who did or did not develop post-operative bleeding to delineate when hemoglobin trends diverge. METHODS: Patients who underwent sleeve gastrectomy or gastric bypass at a single center from 2020 to 2024 were stratified into those who did or did not develop bleeding that required transfusion and/or surgical or endoscopic intervention. Three standardized hemoglobin draws (pre-operative, four-hour post-operative, morning of post-operative day 1) were compared between groups. Time to the first clinical sign of bleeding and intervention were evaluated for patients who developed clinically significant bleeding. RESULTS: 1,457 patients were included (mean [SD] age 45.4 [10.8] years; 85.5% White; 82.0% female, 60.6% sleeve gastrectomy). Thirty-nine patients (2.7%) developed bleeding. Mean pre-operative and four-hour post-operative hemoglobin values were similar. Hemoglobin values on the morning of post-operative day 1 were significantly lower for the patients who bled [10.7 g/dL (SD 1.6) vs. 12.5 g/dL (1.1); p < 0.001]. The median time to the first clinical sign of bleeding was 9 h (IQR 6.25-17.5). The median time to intervention was 23 h (17-32). CONCLUSION: Hemoglobin trends remained similar between groups until the morning of postoperative day 1. Clinical signs of bleeding did not develop until after the typical same day surgery observation period for most patients. These findings suggest that patients who develop clinically significant bleeding after same day bariatric surgery may not be identifiable prior to discharge and that next day discharge is a safer alternative. KEY POINTS: • Post-operative hemoglobin values after bariatric surgery were compared between patients who did or did not develop post-operative bleeding. • Hemoglobin values were similar until the morning of post-operative day 1. • The first clinical signs of bleeding developed at a median of 9 h after surgery. • Some patients who develop clinically significant bleeding after same day bariatric surgery may not be identified prior to discharge.