Laparoscopic Gastric Bypass

Bariatric Surgery at NewYork-Presbyterian/Queens
56-45 Main Street
Flushing, NY 11355 

Phone: (718) 445-0220, ext. 9

Gastric bypass using the "roux-en-Y" procedure is the standard to which all other obesity operations are compared. It has consistently produced the most dramatic and lasting weight loss in patients with marked obesity and co-morbid conditions, and is the most commonly performed obesity procedure in the United States.

The operation consists of two components, referred to as a "restrictive" component and a "malabsorptive" component. The restrictive part involves reduction of the stomach volume to about 20 cc, thereby limiting the amount of food that can be eaten. Bypassing a segment of small intestine decreases the amount of fat and calories that can be absorbed, thus providing the malabsorptive component. Many studies have shown that this type of combined procedure will produce greater weight loss than will restrictive procedures alone.

The anatomy produced by this surgery also makes it difficult for patients to eat foods high in sugar and calories without developing abdominal discomfort from "dumping syndrome." This effect serves to further encourage patients to avoid calorie-dense foods whose use might otherwise defeat the operation. Although it is technically possible to reverse gastric bypass, the anatomic changes produced should be considered permanent.

Laparoscopy is a technique that allows surgeons to visualize and manipulate structures within the abdominal cavity without making long incisions through the abdominal wall. This means less pain and scarring for the patient and a shorter recovery.

The technique used for gastric bypass surgery involves the placement of 3 to 6 tubes (called "ports") into the abdomen through which instruments and a video camera can be passed. The abdomen is distended with carbon dioxide gas, creating an "optical cavity" within which the surgeon's camera can "see", and gives the surgeon "room to work."

Laparoscopic gastric bypass is a complex surgery that requires considerable training and skill on the part of the surgeon. This type of surgery should not be performed by just any surgeon or in just any institution, but only by those with extended, specific training and experience. A dedicated peri-operative and operating room team are critical to success in this area.

Please note that not all patients who are candidates for gastric bypass are appropriate candidates for laparoscopic techniques. The surgeon's experience will help him/her make good judgments about choice of technique in each case.
Why It Works

Weight loss begins immediately after surgery and is initially quite rapid. Although weight loss continues for 1 1/2 to 2 years, up to 90% of the loss occurs within the first 12 months. Weight loss occurs for several reasons:

  • Small Gastric Pouch: The gastric pouch after the operation is only about the size of a golf ball. This small size limits the amount of food that can be eaten at one sitting. After about 4 oz. of food is swallowed, stretch receptors in the wall of the pouch produce a "full" feeling. Eating more once this has occurred can produce vomiting and pain.
  • Small Gastric Outlet: The size of the connection between the pouch and the intestine causes slow emptying of the pouch. This makes the patient feel full for some time after eating and prevents unlimited flow of food from the stomach.
  • Gastric Bypass: The bypassed small intestine carries food through it, but does not allow mixing of food with enzymes and bile until the lower intestinal connection is reached. This means that digestion and absorption do not occur in the bypassed segment. Also,symptoms like abdominal pain, nausea, palpitations sweating and diarrhea ("dumping syndrome") may occur if sugars pass rapidly into the bypassed segment. This keeps patients away from high calorie foods.

The Operation  

In the first stage of the procedure, access is gained to the abdomen and the first portion of the small intestine (called the "jejunum") is identified near its attachment to the duodenum. A segment of small bowel is measured for bypass, the distance that is selected is dependant upon the pre-operative BMI of the patient. (Patients who are more severe obesity will need a longer bypass segment.) The intestine is divided at the appropriate point. Following this, the distal piece is stretched out and the proximal piece is reconnected to the distal piece the measured distance down the limb.

Next, the colon and stomach are raised and an opening created into the space behind the stomach. (It is through this passageway that the bypassed intestinal limb will get up to the stomach pouch that will soon be made.)

The liver is retracted to expose the upper stomach. Staplers are used to carefully separate a small pouch of stomach from the main body of the organ, just below the point where the esophagus enters. Once the staple lines are complete, the pouch can be completely separated from the rest of the stomach.

In the final step of the procedure, the bypassed small intestine is tunneled behind the stomach to reach the gastric pouch. It is joined with the pouch and the seal of the connection is tested.

After surgery, patients will usually have one or two intravenous lines, a urinary catheter and a soft, plastic drain coming out of one of the incisions. The urinary catheter will be removed the day after surgery, and the wound drain will be removed the day of discharge.

While in the hospital, the patient is seen by a number of team members, including the surgeon, his residents and fellow, nurses and nurses aids. On the morning after surgery, each patient undergoes a test called an esophogram in the radiology department. This is an xray that helps to make certain that the top connection between the gastric pouch and small intestine is intact. When the result of the study is normal, the patient will be started on clear liquids by mouth, and will likely be sent home on the second or third post-operative day. Before discharge the patient is changed from pain medicine injections to the use of pain pills.

During the first week at home the patient remains on a liquid diet. After that week patients begin on a soft diet that will transition to regular foods in about 2 to 3 weeks, (see post-op nutrition care).


Despite excellent surgical care and 100% patient compliance, complications can still occur. It is also important to recognize that all patients do not face equal risks, (patients are defined as "low" or "high" risk). Low risk patients are more likely to recover quickly and without complication. These are usually people under 40 years old who have BMIs below 50 and only one or two complications of the disease. High risk patients are older, with higher BMIs and more medical problems. Although these patients can be operated upon safely, their treatment requires greater pre-operative planning and evaluation.

Certain medical problems also increase a person's risk, including diabetes, heart disease, steroid-dependant asthma and conditions requiring the use of coumadin (blood thinner). Also, a number of things may make conversion to open surgery from laparoscopic technique necessary, including fragile tissues, small intestinal caliber, poor blood clotting or scar adhesions inside the abdomen.

Early In-Hospital Complications

Death:  0.5% (1 in 200)

Anastomotic Leak: Leakage can occur from any of the various staple lines. If a leak is detected early after surgery a new laparoscopic or open procedure will be carried out to repair it. A slow, undetected leak can lead to abdominal abscess and sometimes to generalized peritonitis. The risk of leak is 1-3%.

Intestinal Complications: Scars ("adhesions") that form in the abdomen after surgery can lead to intestinal blockage. This is less likely after laparoscopic surgery ( incidence less than 1%). Rarely, a narrowing of the lower intestinal connection can occur, requiring surgical revision.

Bleeding: This can occur with any surgery, although the bleeding is usual minimal from bypass operations. Bleeding can occur from any of the staple lines or from large vessels around the stomach. The need for transfusions has been extremely low, and no patients have undergone re operation for bleeding.

Wound Complications/Infections: Wound infection is rare with laparoscopic surgery's small incisions. Most such infections can be treated in outpatients with local wound care and oral antibiotics. Serious wound infections requiring hospitalization happen in fewer than 1% of cases. Hernias are also rare with laparoscopy and the overall wound complication rate for minimally invasive procedures is less than 5% (compared to greater than 20% with open procedures).

Blood Clots, Pulmonary Embolus Clots: These can form in thigh or pelvic veins during or after surgery. If such clots break free and travel through the blood stream to the lung they can be life-threatening. Three techniques used to minimize risk for clots include the use of special massage stocking in the operating room, the use of blood thinners and early ambulation after surgery.

Anesthetic Complications: Airway control is more difficult in the obese patient, and the metabolism of anesthetics is altered by large fat stores. Happily, the anesthesiologists at NewYork-Presbyterian/Queens are particularly skilled in the management of the bariatric patient, and problems have been rare.

Respiratory/Pneumonia: After any abdominal surgery patients do not breathe as deeply because of pain. Though pain is less with laparoscopic surgery, measures are still taken to limit the risk for pneumonia with adequate pain relief and the use of deep breathing exercises.

Late Post-Hospital Complications (after 1 month)

Anastomotic Stricture: Scar that forms normally at the point where the gastric pouch and intestine meet can sometimes narrow the connection between the two, leading to vomiting. This most often occurs 3 to 6 weeks post-operatively, but can happen up to 12 months afterward. This is the most common complication seen with this procedure (10-15%), but can usually be solved without need of operation when the gastroenterologist dilates the area by passing a balloon down to it from the mouth.

Malnutrition: Because the stomach and proximal bowel are responsible for the absorption of some essential nutrients, their bypass can lead to deficiencies. In particular, the need for lifelong supplementation of vitamin B12, folic acids, iron and calcium is critical. Blood tests are performed at 3-6 months post-operatively, and yearly thereafter to monitor patient nutrition. With proper supplementation, deficiencies should be rare.

Gallstones: During rapid weight loss, 30% of patients will develop gallstones. This can be reduced to 2% by the use of medication called Actigall for 6 months. For any who develop symptomatic stones despite this, laparoscopic gallbladder removal is offered. Patient who have symptomatic gallstones before gastric bypass will undergo gallbladder removal at the time of the bypass.

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