Laparoscopic Gastric Bypass

Updated: May 03, 2021
Author: Subhashini Ayloo, MD; Chief Editor: Kurt E Roberts, MD 



Laparoscopic gastric bypass (GBP) surgery 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 gastric bypass is the one-anastomosis (mini) gastric bypass.[4, 5]  Robot-assisted approaches to gastric bypass and other bariatric procedures have been described as well.[6, 7, 8]  

More than 100 million Americans (65% of the adult population) are overweight.[9] 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.[9, 10] 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.[9, 10] Morbid obesity is defined as severe obesity that threatens one’s health and can shorten lifespan.[9]

Body mass index (BMI) describes relative weight for height and correlates significantly with an individual’s total body fat.[10] BMI is based on height and weight and applies to adults of both sexes. BMI is calculated in one of two ways, as follows[9, 11] :

  • 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.[11] 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.[12, 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 GPB, laparoscopic sleeve gastrectomy, and laparoscopic adjustable gastric banding with respect to effectiveness and safety in 150 consecutive bariatric surgery patients followed for 2 years.[13] Bypass yielded a greater change in BMI than either sleeve gastrectomy or gastric banding, 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.[14] 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.[15] 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 GBP both in the midterm (3-5 years) and in the long term (≥5 years), 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.[16] 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.[17]

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.[7]  However, robotic GBP appears to be associated with greater resource utilization.[8]


Periprocedural Care


Equipment required for laparoscopic gastric bypass (GBP) includes the following:

  • Laparoscopic tray with full set of instruments, including graspers, dissectors, endoscopic gastrointestinal anastomosis (GIA) staplers, and silk and polyglactin sutures
  • Energy source
  • Staple-line reinforcers (eg, Seamguard)
  • Trocars, 5 mm and 10-12 mm
  • Orogastric tube
  • Nathanson liver retractor

Patient Preparation

General anesthesia is required for a laparoscopic GBP procedure.

The patient is positioned either supine with the arms extended outward or in the lithotomy position, depending on the placement of the trocars. The surgeon should be standing comfortably with the arms and elbows in an abducted position.



Laparoscopic Roux-en-Y Gastric Bypass

Before the procedure is started, the monitors should be adjusted so that they can be viewed at eye level. The trocars should be positioned at least a fist-length apart. This allows the surgeon to use both hands comfortably. A preoperative liquid diet seems to help decrease the size of the liver.

The operation is initiated by placing a total of six trocars, of which four are 10 mm and two are 5 mm.

Some of the gastrophrenic ligaments are taken down at the angle of His. A small gastric pouch is created by creating a window in the lesser sac. A stapler is used to staple and transect the stomach first horizontally and then vertically to the angle of His. A Maloney dilator is used to guide in creating the pouch (see the video below).

Laparoscopic gastric bypass: part 1.

The omentum and the transverse colon are retracted cranially, and the ligament of Treitz is thereby exposed. The small bowel and its mesentery are stapled and transected at the jejunum. A Roux limb of 150 cm is bypassed.

A jejunojejunal anastomosis is performed. The common enterotomy of the jejunojejunal anastomosis is sewn by hand in a double-layered fashion. The mesenteric defect is closed (see the video below) so as to prevent internal hernias.

Laparoscopic gastric bypass: part 2.

The Roux limb is brought out in an antecolic and antegastric manner. A gastrojejunal anastomosis between the pouch and the Roux limb is performed in a double-layered fashion as well.[18] A gastrotomy and an enterotomy are created. An orogastric tube is advanced through the gastrojejunal anastomosis.The anterior layer of the gastrojejunal anastomosis is closed in a double-layered technique. The gastrojejunal anastomosis is tested for air leak by submerging the anastomosis with irrigation fluid and inflating the orogastric tube with air (see the video below).

Laparoscopic gastric bypass: part 3.

The anastomosis (gastrojejunal or jejunojejunal) can be either handsewn or stapled. Using the staple line reinforcer (eg, Seamguard, Peristrips) appears to reinforce the staple line.

Recommendations vary with respect to when patients should be discharged after the procedure. A 2014 study from the United Kingdom found a 23-hour postprocedure stay to be safe and cost-effective.[19] Same-day discharge has been tried, but some have found it to be associated with increased morbidity and mortality.[20]  A 2021 single-center study from The Netherlands found same-day discharge after laparoscopic Roux-en-Y gastric bypass to be feasible in selected patients with the use of remote monitoring.[21]


Laparoscopic Roux-en-Y GBP is a major elective surgical procedure. Risks include the following:

  • Mortality (1-2% of patients), mainly due to pulmonary embolism or gastrointestinal leak
  • Wound infections (possibly more common with the use of tissue adhesive for wound closure [22] )
  • Gastrojejunal stomal stricture
  • Marginal ulcers (possibly more common with an antecolic approach than with a retrocolic approach [23] )
  • Internal hernia
  • Roux limb ischemia
  • Blowout of the stomach remnant
  • Long-term deficiencies of micronutrients (eg, vitamin B12, folate, iron)

Bleeding from the staple line, though rare, can be a serious problem after laparoscopic GBP. It may be controlled by means of clipping or monopolar cauterization.[24]

In a large study (N = 42,345) that included a substantial population of older adults, Yu et al found that Roux-en-Y gastric bypass (n = 29,624) was associated with a 73% increased risk of nonvertebral (eg, hip, wrist, and pelvis) fracture after the procedure as compared with adjustable gastric banding (n = 12,721).[25] The difference in postoperative fracture risk between the two procedures was consistent across different subgroups and occurred to a similar degree among older and younger adults.