Malnutrition After Malabsorptive Metabolic Bariatric Surgery: When Should the Surgery Be Reversed?

BACKGROUND: Metabolic bariatric surgery (MBS) is the most successful way to tackle obesity and its related diseases. However, long-term side effects can arise. One rare but serious complication is severe protein-energy malnutrition, which may need surgery to reverse the effects on gut absorption function. OBJECTIVES: We aimed to analyze the clinical, anthropometric, and biochemical criteria, as well as the operative outcomes for patients who underwent reversal surgery, and to assess the preoperative parameters that led to the decision to reverse bariatric surgery in patients with malnutrition. METHODS: A retrospective cohort study was conducted on all patients who underwent MBS over a five-year period (from July 2018 to July 2023) at the bariatric tertiary unit of Homerton University Hospital in London, UK. RESULTS: From a total of 645 cases that underwent MBS, nine (1.4%) patients required some form of reversal procedure due to severe malnutrition. All patients exhibited severe hypoalbuminemia (mean albumin level of 17.2 g/L), iron deficiency anemia (mean hemoglobin level of 104.67 g/L), and micronutrient deficiencies. They also presented with excess weight loss (mean percent excess weight loss (%EWL) of 119.3%). This necessitated admission for parenteral nutrition and trace elements infusion to optimize the patients' condition before reversal/revision surgery. Eight out of nine patients showed improvement after reversal/revision surgery, while one patient remained malnourished. The decision to offer reversal surgery and the type of surgery performed were based on local individual case assessments and multidisciplinary team (MDT) discussions. CONCLUSIONS: Severe malnutrition following bariatric surgery is rare (1.4%) but serious. Reversal procedures are effective treatment options; however, they should be performed by an expert team in tertiary centers. While certain clinical features were commonly observed in our patient series, these findings cannot be generalized due to study limitations. Nonetheless, they can help inform future research. The question of when to perform reversal procedures remains unresolved, underscoring the need for larger, multicenter studies to better define indications and optimal timing.