Background

It's well established that extending either the biliopancreatic limb (BPL), the alimentary limb (AL), or both, to increase the total bypass length (TBL) results in amplified weight loss and nutritional deficiencies due to heightened malabsorptive effects. However, a key question remains: does the significance of each limb's contribution to TBL affect outcomes? To explore this, we collated studies comparing long BPL and long AL while maintaining similar or near-equal TBL.

Methods

Following the PRISMA guidelines, we conducted a systematic literature review. The random effects model was employed, utilizing odds ratios for dichotomous data and mean differences for continuous data as effect size metrics.

Results

At 6, 9, 12, 24, 36, and 48 months, TWL% and EWL% were significantly higher in the long BPL group. Incidences of leaks, abscesses, dumping, and reoperations were insignificantly lower in the long BPL group. Incidences of abnormally low ferritin, diarrhea, internal hernia, and bleeding were insignificantly higher in the long BPL group. No differences were observed in incidences of anemia and vitamin D deficiency between the groups.

Conclusions

Weight loss after RYGB may not solely depend on the restrictive effect of the gastric pouch or the malabsorptive effect of bypassed intestines but could potentially involve alterations in entero-pancreatic hormones (GLP, GIP, PYY, etc), possibly influenced by increasing the BPL limb as indicated by basic science research. Further studies comparing comorbidity resolution are necessary. The impact of BPL length in RYGB on clinical and metabolic outcomes remains an intriguing topic for clinicians and basic scientists.