RESUMEN
Severe malnutrition following one-anastomosis gastric bypass (OAGB) remains a concern. Fifty studies involving 49,991 patients were included in this review. In-hospital treatment for severe malnutrition was needed for 0.9% (n = 446) of patients. Biliopancreatic limb (BPL) length was 150 cm in five (1.1%) patients, > 150 cm in 151 (33.9%), and not reported in 290 (65%) patients. OAGB was revised to normal anatomy in 126 (28.2%), sleeve gastrectomy in 46 (10.3%), Roux-en-Y gastric bypass in 41 (9.2%), and shortening of BPL length in 17 (3.8%) patients. One hundred fifty-one (33.8%) patients responded to treatment; ten (2.2%) did not respond and was not reported in 285 (63.9%) patients. Eight (0.02%) deaths were reported. Standardisation of the OAGB technique along with robust prospective data collection is required to understand this serious problem.