RYGB: No differences in outcomes between short and long-length BPL

A meta-analysis of randomised controlled trials (RCTs) that assessed the difference in outcomes between short and long-length biliopancreatic limb (BPL) in the setting of Roux-en-Y gastric bypass (RYGB) has reported that there are no significant differences in weight change, resolution of metabolic comorbidities or complications, according to researchers from Imperial College London (ICL). The findings were featured in the paper, ‘Length of biliopancreatic limb in Roux-en-Y gastric bypass and its impact on post-operative outcomes in metabolic and obesity surgery - systematic review and meta-analysis’, published in Nature’s International Journal of Obesity.

RYGB has been practiced for decades and is believed by many bariatric surgeons to be the gold-standard procedure. Some studies have shown that a longer BPL may be associated with superior outcomes with respect to glycaemic control compared to a standard RYGB. However, with several observational studies and some RCTs supporting or disputing the importance of BPL elongation in RYGB, there is no consensus on the optimal BPL length when performing a RYGB.


Therefore, researchers at the ICL performed systematic review and meta-analysis to determine whether BPL length in RYGB affects postoperative outcomes including change in weight, body mass index (BMI) and resolution of metabolic comorbidities associated with obesity.


After performing a literature review, the authors identified ten RCTs and reported that:

  • Short (or standard) BPL length varied from 15 to 75cm, with 50cm being the most common

  • In the long BPL cohort, BPL length ranged between 30 and 200cm, with 150cm being bypassed most frequently

  • Reported alimentary limb length was 60–250cm, with 150cm being the most common measurement.

In total, seven trials compared short vs long BPL whilst forming an AL of a varying length, and the remaining three RCTs had a single standard AL length.

The primary outcomes measure in five studies was percentage of the total body weight loss at 12 months (436 patients - short limb (n=220) and long limb (n=216) cohorts). The were no statistically significant differences between the two cohorts (p=0.32).


Four studies evaluated percentage of the total body weight loss at 24 months (383 patients - short limb (n=193) and long limb (n=190) cohorts. There was a higher weight loss of statistical significance for the long limb cohort (p=0.01).


However, from the three studies (330 patients - short limb (n=161, long limb n=169) with total body weight loss at 48–72 months, there were no statistically significant differences between the two cohorts (p=0.99).


Five studies included measured change in BMI at 12 months with 797 patients (short limb n=400) and long limb n=397) and reported no statistically significant difference between the two cohorts (p=0.20).


Regarding metabolic resolution of comorbidities, the study report that:

  • There were no statistically significant differences between the two cohorts regarding remission or improvement in T2DM at 12 months (p=0.54) or 24–60 months post-operatively (p=0.71).

  • There were no statistically significant differences between the two cohorts regarding remission or improvement in hypertension (p=0.29).

  • ·There were no statistically significant differences between the two cohorts regarding remission or improvement in dyslipidaemia (p=0.14).

In addition, the incidence of complications was similar from the five studies that recorded post-operative complications (531 patients - short limb (n=272) and long limb (n=259), p=0.22).

Given these outcomes from their meta-analysis, the researchers stated that the evidence does not support the proposed theory on superior weight loss, improved glycaemic control nor higher remission of obesity-related comorbidities in RYGB with a long biliopancreatic limb.

“…there remains a paucity of investigations into the physiological changes which result in the observed outcomes following RYGB,” the authors concluded. “Through dedicated investigation this would allow a better understanding of mechanisms of action, thereby informing surgical design based upon a first-principles approach.”

Further information


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