Laparoscopic Gastric Bypass

Updated: Apr 26, 2023
  • Author: Subhashini Ayloo, MD; Chief Editor: Kurt E Roberts, MD  more...
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Laparoscopic gastric bypass (GBP) is a surgical procedure that involves the creation of a gastric pouch and is performed to yield significant and long-lasting weight loss in patients who are severely obese—that is, a bariatric (a term derived from the Greek words baros ["weight"] and iatrikos ["pertaining to a physician"]) procedure. [1, 2, 3] An alternative to the standard laparoscopic Roux-en-Y GBP is the one-anastomosis (mini) GBP. [4, 5, 6, 7] Robot-assisted approaches to GBP and other bariatric procedures have been described as well. [8, 9, 10]

More than 100 million Americans (~65% of the adult population) are overweight. [11] Obesity is the second leading cause of preventable death in the United States after smoking. Annually, obesity-related diseases account for 400,000 premature deaths.

A combination of genetics, environmental issues, and behavioral factors may contribute to the condition. [11, 12] Consumption of high-calorie foods, consumption of too much food, and a sedentary lifestyle all work together to create this condition. Obesity is associated with the development of diabetes mellitus, hypertension, dyslipidemia, arthritis, sleep apnea, cholelithiasis, cardiovascular disease, and cancer. [11, 12] Morbid obesity is defined as severe obesity that threatens one’s health and can shorten lifespan. [11]

Body mass index (BMI) describes relative weight for height and correlates significantly with an individual’s total body fat. [12] BMI is based on height and weight and applies to adults of both sexes. BMI is calculated in one of two ways, as follows [11, 13] :

  • BMI = weight (kg)/(height [m]) 2
  • BMI = weight (lb)/(height [in.]) 2 × 703

Obesity can be treated medically and surgically. Medical treatment for obesity is difficult, because the amount of weight lost is small and patients tend to regain most of the weight. Bariatric surgery is currently the only modality that provides a significant, sustained weight loss for morbidly obese patients.

For information on laparoscopic gastric banding (another form of bariatric surgery), see Laparoscopic Gastric Banding.



In 1991, the National Institutes of Health (NIH) provided a consensus statement for patient selection for bariatric surgery. [13] Patients were considered candidates for surgery if they met one of the following criteria:

  • BMI higher than 40
  • BMI of 35-40 plus one of the following obesity-associated comorbidities: (1) severe diabetes mellitus, (2) pickwickian syndrome, (3) obesity-related cardiomyopathy, (4) severe sleep apnea, or (5) osteoarthritis interfering with lifestyle

To be candidates for bariatric surgery, patients should have attempted, without success, to lose an appropriate amount of weight through supervised diet changes. [14, 3] Patients must also comply with postoperative diet and exercise.

Clinical guidelines for the clinical application of laparoscopic bariatric surgery have been developed by the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES). [3]



Contraindications for GBP surgery include the following:

  • History of substance abuse
  • History of major psychiatric disorder
  • End-stage organ disease (eg, hepatic, cardiac, pulmonary)

Bariatric surgery is only a tool for weight loss. Patients who are not committed to making long-term lifestyle changes are not ideal candidates for this procedure.



Gill et al compared laparoscopic Roux-en-Y GBP, laparoscopic sleeve gastrectomy, and laparoscopic adjustable gastric banding (LAGB) with respect to effectiveness and safety in 150 consecutive bariatric surgery patients followed for 2 years. [15] Bypass yielded a greater change in BMI than either sleeve gastrectomy or LAGB, as well as a greater reduction in obesity-related comorbidities (though all three procedures were judged to be safe).

Rausa et al compared the complications and 30-day mortality of laparoscopic Roux-en-Y GBP with those of the equivalent open procedure. [16] The meta-analysis and meta-regression analysis included 17 papers published between 2000 and 2014. A higher mortality was noted for open surgery (death rate, 0.82%) than for laparoscopic surgery (death rate, 0.22%). Contemporary reports of laparoscopic Roux-en-Y GBP have cited low mortality figures and progressively declining postoperative complication rates for laparoscopic GBP.

de Raaff et al studied the persistence of moderate or severe obstructive sleep apnea after laparoscopic Roux-en-Y GBP. [17] They found that predictive factors for such persistence included the following:

  • Age 50 years or older
  • Preoperative apnea-hypopnea index 30/hr or higher
  • Excess weight loss of less than 60%
  • Hypertension

In a systematic review and meta-analysis of comparative studies investigating weight loss and resolution of comorbidities for laparoscopic Roux-en-Y GBP and laparoscopic sleeve gastrectomy both in the midterm (3-5 y) and in the long term (≥5 y), Shoar et al found no significant difference in midterm weight loss but did find a significant difference in long-term weight loss that favored laparoscopic Roux-en-Y GBP. [18] They found no significant difference between the two procedures with regard to resolution of comorbidities (eg, type 2 diabetes mellitus, hypertension, hyperlipidemia, and hypertriglyceridemia).

In a prospective study comparing laparoscopic Roux-en-Y GBP and laparoscopic sleeve gastrectomy with respect to changes in body composition, dietary intake, and substrate oxidation 6 months postoperatively, Golzarand et al found the two procedures to have similar effect on total and regional fat mass and fat-free mass, dietary intake of macronutrients, and substrate oxidation. [19]

In a study that used the 2015-2016 Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) database to compare 30-day outcomes between robotic-assisted and laparoscopic approaches to Roux-en-Y GBP and sleeve gastrectomy, Sebastian et al found that for Roux-en-Y GBP in particular, the robotic approach significantly reduced postoperative bleeding and blood transfusion and, after correction for relevant factors (eg, operating time), was associated with better postoperative outcomes. [9]  However, robotic GBP appears to be associated with greater resource utilization. [10]

In a systematic review and meta-analysis of randomized controlled trials, Osland et al compared the 5-year outcomes of laparoscopic vertical sleeve gastrectomy with those of laparoscopic Roux-en-Y GBP. [20]  Both procedures yielded long-term improvements in commonly experienced obesity-related comorbidities. Although there were trends favoring one procedure or the other with respect to particular comorbidities, the limited quality of the currently available evidence did not permit strong conclusions to be made as to which procedure was superior.