A Protocol for Roux-en-Y Gastric Bypass in Rats using Linear Staplers

Roux-en-Y gastric bypass is a commonly performed procedure for the treatment of severe obesity and type 2 diabetes. However, the exact mechanisms contributing to weight loss and metabolic improvement are not well understood and multiple factors are thought to play a role. The rat Roux-en-Y gastric bypass model presents an excellent framework to study these mechanisms.Protocol.

Preparation of animals and operative setup. Clean the abdomen with a povidone-iodine solution. Allow the solution to dry and change into sterile gloves.

Drape the rat with an opening in the drape to expose the abdomen. Instruments, sutures, cotton swabs, and a 10 milliliter syringe are placed in a location that permits easy access during the procedure. Median laparotomy.

Make a three centimeter incision in the upper midline of the abdomen using a scalpel, just below the xiphoid process as a landmark. Using scissors, divide the fascia and peritoneum, with care to stay midline on the linea alba to reduce bleeding from the rectus abdominis. If there is bleeding, control it with thermal or electrocautery.

Mobilizing the stomach. Using two wet cotton swabs, bluntly dissect gastric attachments. When encountering dense adhesions, use thermal cautery to divide gastric attachments, with care to avoid cauterizing the stomach.

Sharply divide the ligament between the stomach and the accessory liver lobe to reduce the risk of liver tearing with stomach mobilization. For larger blood vessels, especially at the short gastric arteries, ligate using 6-0 polypropylene. Create a window on the right distal side of the esophagus but proximal to the left gastric artery.

Ensure that a cotton swab can reach into this area posteriorly. The stomach is adequately mobilized when it can be exteriorized outside of the abdomen. Identify and divide the jejunem.

Identify the ligament of Treitz by following the jejunum proximally until observing its attachment to the transverse mesocolon. Measure seven centimeters distally, identify a location between mesenteric vessels, and divide the bowel with micro scissors. Avoid Peyer's patches when dividing the bowel.

Take care to only divide the bowel and not the mesentery. Place a clean, saline-soaked sponge prior to dividing the bowel to minimize contamination. A small crossing vessel is typically present in the mesentery at the border of the small bowel and this is divided with cautery to avoid bleeding.

Continue to divide the mesentery one centimeter towards the mesenteric base. Identify the proximal and distal jejunem. Place the proximal jejunum under a wet gauze on the rat's right and the distal jejunum on the rat's left.

Stapling the stomach. Insert a 45 millimeter linear cutting stapler with 3.5 millimeter staple height across the white line of the forestomach to create a smaller pouch. Wait 10 seconds before firing the stapler.

Place pressure using gauze on the staple lines for one minute to ensure hemostasis. If hemostasis is not achieved with pressure alone, bleeding along the staple line is oversewn using 6-0 polypropylene figure-of-eight sutures. A second staple fire is then performed across the stomach into the window created previously.

Wait 10 seconds before firing the stapler. Pressure is held along the staple line to ensure hemostasis and oversewing may be needed.Gastrojejunostomy. A gastrotomy is made immediately after stapling the stomach.

Delays in this can cause gastric distension and aspiration as the stomach is discontinuous after the second gastric staple. Using an 11 blade scalpel, create a gastrotomy at the distal pouch. Express gastric contents through the gastrotomy.

This is important to prevent gastric distension and aspiration. Lengthen this gastrotomy using micro scissors to approximately five millimeters. Express gastric contents through the gastrotomy.

Mobilize the distal end of the jejunum adjacent to the gastrotomy and place such that the mesentery is not twisted. While suturing the anastomosis, ensure that the bowel is kept moist by covering it with saline-soaked gauze and reapplying saline regularly. Using 6-0 polydioxanone or polypropylene suture, place a stay suture at the inferior margin of the anastomosis and gently retract using a snap.

Tie with three knots. Place a stay suture at the superior margin of the anastomosis and gently retract using a snap. Tie with six knots.

Suture the anterior side of the anastomosis in a continuous fashion taking bites one millimeter wide and one millimeter apart with care to avoid taking the backside. Once the suture has reached the inferior stay suture, tie these together with an additional six knots. Once the anterior side is complete, flip the bowel and stomach over and pass the inferior stay suture through the mesenteric defect.

Reapply the snap and retract inferiorly. For the posterior side of the anastomosis, place full-thickness, interrupted 6-0 sutures one millimeter wide and spaced one millimeter apart with care to avoid taking the backside. These are tied with six knots each.

Note the anterior side of the anastomosis is sutured in a continuous fashion while the posterior side is done in an interrupted fashion. This prevents potential stricture or stenosis associated with a circumferential continuous closure. Check for leakage by gently pushing luminal contents across the anastomosis.

If there are areas with leakage, carefully reinforce them with interrupted sutures. Take care to avoid taking the back wall when reinforcing with extra sutures.Jejunojejunostomy. From the gastrojejunostomy, measure 20 centimeters distally.

Create a jejunotomy on the antimesenteric side using the 11 blade scalpel. Avoid making the jejunotomy over Peyer's patches. Extend this jejunotomy using micro scissors such that it is the same size as the biliopancreatic limb.

Ensure that a cotton swab just fits inside. Place the biliopancreatic limb such that there is no twisting of the mesentery. Perform the anastomosis similarly to the gastrojejunostomy with 6-0 stay sutures on the superior and inferior sides.

The anterior side is performed with continuous sutures while the posterior side is performed with interrupted sutures. Ensure that the bowel is kept moist with saline during this anastomosis. Check for leakage by gently pushing luminal contents through the anastomosis.

If there are areas with leakage, reinforce them with interrupted sutures. Reposition the bowel and stomach. Ensure that there is no twisting of the pouch, remnant stomach, or liver.

Ensure that the left lobe of the liver is anterior to the stomach and not trapped behind the pouch as this can cause compressive liver ischemia. Abdominal closure. Close the fascia with 3-0 polyglactin in a continuous fashion.

3-0 polydioxanone may also be used. Close the skin with 2-0 silk in a continuous fashion.Results. All cohorts had significant weight gain preoperatively.

Rats undergoing Roux-en-Y gastric bypass had lower postoperative weight on a high-fat diet compared to rats undergoing sham surgery. The postoperative weight change on a high-fat diet was statistically significant at all time points postoperatively. There was improved glucose tolerance after Roux-en-Y gastric bypass with a lower area under the curve during intraperitoneal glucose tolerance testing compared to sham surgery.Conclusion.

This procedure utilizes linear staplers in a rat model to perform Roux-en-Y gastric bypass resulting in a gastric pouch more in keeping with that of human anatomy. Overall, this procedure was associated with excellent survival rates and significant weight loss and metabolic effects.