The rise of ileal bypass surgery in the United States: A cautionary tale for Metabolic and Bariatric Surgery: From jejuno-ileal bypass to duodeno-ileal bypass

Abstract The landscape of metabolic and bariatric surgery (MBS) has become increasingly complex with the proliferation of intestinal bypass procedures and the rise in ileal bypass (IBS) procedures (SADI-S and DS) in the United States, alongside a confusing array of procedure names that fail to reflect underlying physiology. We propose an anatomy-based classification distinguishing jejunal bypass (JBS), including RYGB, OAGB, and SASJ, from ileal bypass (IBS), including SADI-S, BPD/DS, SASI, and type I distalization, based on the site of intestinal anastomosis. This classification enables better patient selection, facilitates benefit-risk assessment of new procedures like SASJ and SASI, highlights the importance of standardized measurement of biliopancreatic limb (BPL) length, common channel (CC), and total alimentary limb length (TALL) to prevent malnutrition, and promises to improve comparative research, individualized procedure selection, and future surgical innovation.