Biliopancreatic Diversion With Duodenal Switch

Anatomy and Physiology

The anatomy relevant to the biliopancreatic diversion with duodenal switch includes the stomach, the surrounding structures, and the vascular supply from the superior mesenteric artery and celiac trunk.

Stomach

The stomach is a muscular tube that begins at the gastroesophageal junction and extends from the lower esophageal sphincter to the first portion of the duodenum. The stomach is divided into 5 portions, which include the cardia, which is the portion distal to the gastroesophageal (GE) junction. The fundus abuts the left diaphragm, body, antrum, and pylorus, which is the most distal portion entering the duodenum. The greater curvature is the long left lateral border of the stomach, which extends from the fundus to the pylorus. The greater curvature is connected to the greater omentum. The lesser curvature lies beneath the liver and contains the incisura angularis, the transition point from the body of the stomach to the antrum. Posterior to the stomach lies the lesser sac, which includes the pancreas.

Ligaments

The primary ligaments involved include:

• Gastrophrenic ligament: Connects the fundus to the left hemidiaphragm
• Gastrohepatic ligament: Connects the lesser curvature to the medial liver edge. The left and right gastric arteries run within the gastrohepatic ligament.
• Gastrosplenic ligament: Connects the greater curvature to the spleen and contains the short gastric vessels
• Gastrocolic ligament: Connects the inferior stomach to the transverse colon and is part of the greater omentum. The gastroepiploic vessels can be found within the gastrocolic ligament.

Vascular Supply

The celiac artery has 3 major branches: the left gastric, the common hepatic, and the splenic arteries. The left gastric artery is located on the superior lesser curvature and combines with the right gastric artery. The common hepatic artery gives off the gastroduodenal artery, which runs behind the first portion of the duodenum. After the gastroduodenal artery comes off, the common hepatic artery becomes the proper hepatic artery. The right gastric artery is a typical branch off the proper hepatic artery and joins the left gastric artery on the lesser curvature. The gastroduodenal artery gives rise to the right gastroepiploic artery and runs along the greater curvature before joining the left gastroepiploic artery. The left gastroepiploic artery originates from the splenic artery. The splenic artery also gives off the short gastric arteries, which can be found in the gastrosplenic ligament, which is connected to the gastric fundus.

Physiology

Important hormones directly affected by bariatric surgery and significantly influencing patients' weight loss and outcomes include leptin, incretins (GIP and GLP-1), ghrelin, and insulin.

Ghrelin is a peptide hormone produced by ghrelinergic cells in the gastrointestinal (GI) tract and functions as a neuropeptide in the central nervous system.[5] Ghrelin plays a significant role in regulating the rate and distribution of the use of energy.[6] Ghrelin levels rise during prolonged fasting and drop after eating.[7] Bariatric procedures have variable effects on ghrelin production. This could be due to altered nutrient passage through the gastric fundus, where ghrelin-producing cells are predominantly located.[8] Dirksen et al followed 33 patients for a year after a Roux-en-Y gastric bypass and observed that greater weight loss was associated with greater ghrelin suppression postsurgically.[9] Patients who underwent a sleeve gastrectomy had lower ghrelin levels, likely due to the removal of the part of the stomach that contains ghrelin-secreting cells.[10] This suggests that bariatric surgery affects multiple hormones, which can affect weight loss.

Leptin is a hormone produced by adipose cells and enterocytes. White adipose tissue is the main source of circulating leptin and adiponectin. Leptin's main function is to regulate energy balance by controlling hunger and fat storage. Leptin circulates at concentrations proportional to fat mass and inhibits food intake. In obesity, leptin levels are elevated, primarily due to increased adipose tissue mass.[11] 

With obesity, leptin sensitivity decreases, leading to an inability to achieve satiety. During starvation, leptin levels fall; it crosses the blood-brain barrier and acts via its receptor to inhibit orexigenic and stimulate anorexigenic neuropeptides.[12] Roux-en-Y gastric bypass surgery has been shown to reduce leptin resistance. However, this is proportional to body fat mass in patients.[13]

Incretin hormones such as glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 are secreted, respectively, by K cells in the upper duodenum and by L cells in the ileum.[14] Both are responsible for approximately 50% of postprandial insulin secretion.[15] In addition to their insulinotropic effects, GLP-1 and GIP delay gastric emptying, reduce appetite, promote weight loss, inhibit glucagon secretion, and improve insulin sensitivity.[16][17] Incretins may be impaired in patients who have diabetes. GLP-1 analogs are common antidiabetic agents used today to counteract these effects. Incretin levels have been shown to increase following biliopancreatic diversion and gastric bypass.[18]

Insulin is an amino acid peptide hormone produced by the beta cells of the pancreatic islets. Insulin regulates the metabolism of carbohydrates, fats, and proteins. Insulin is the body's main anabolic hormone. It regulates the absorption of glucose from the blood and regulates the metabolism of glycogen in the liver and skeletal muscles. High blood insulin levels inhibit glucose production and secretion by the liver.[19] 

Decreased insulin sensitivity leads to diabetes mellitus and obesity. Multiple studies have shown that insulin sensitivity improves with all types of bariatric surgery. Hepatic insulin sensitivity has been shown to improve within days of the procedures, and increased peripheral sensitivity follows after.[20] Weight loss leads to a catabolic state, which enhances skeletal muscle insulin sensitivity. Patients who underwent a Roux-en-Y gastric bypass, sleeve gastrectomy, or gastric bypass had 1%, 4%, and 31% of glucose tolerance unchanged, respectively.[21] Bariatric surgery has been shown to prevent the progression of type 2 diabetes.

Indications

The indications for biliopancreatic diversion are primarily bariatric, with a few exceptions. The classic criteria for bariatric surgery are:

• Body mass index (BMI) greater than or equal to 40 and BMI greater than or equal to 35 with at least 1 obesity-related comorbidity (such as diabetes mellitus, obstructive sleep apnea, hypertension, severely limiting musculoskeletal issues)
• Unsuccessful nonoperative weight loss treatments
• Mental health clearance
• No medical contraindications to surgery
• Super obese patients with BMI >50 should be considered for biliopancreatic diversion with duodenal switch [22]

For patients who fail operative treatment with Roux-en-Y bypass and gastric sleeve, biliopancreatic diversion with a duodenal switch should be considered.[22][23]

Contraindications

The contraindications to biliopancreatic diversion with a duodenal switch are primarily related to bariatric procedures. Absolute contraindications for bariatric surgery include the following:

• Pregnancy
• Severe psychiatric illness
• Eating disorders
• Patient-related contraindications to undergo surgery (cardiovascular risk, anesthetic risk)
• Substance misuse (alcoholism)
• Severe coagulopathies [24]

Equipment

Biliopancreatic diversion with duodenal switch can be performed through the open or laparoscopic approach. For this article, we will focus on the laparoscopic approach. The basic laparoscopic equipment needed will include an insufflator with CO₂, sterile surgical drapes, high-definition monitors, laparoscopic instruments, electrocautery devices, and trocars. Bariatric patients typically require longer bariatric trocars and instruments due to the increased thickness of the abdominal wall.

Additional Equipment

• Three 5-mm trocars and 2 12-mm trocars
• A liver retractor 
• 10-mm 30-degree angled laparoscope
• 5-mm laparoscope
• Endoscopic linear stapler
• 32 to 40 French bougie
• Flexible endoscope
• Laparoscopic energy device
• Sutures (silk and Vicryl)

Personnel

Bariatric surgery typically requires a multidisciplinary team that evaluates the patient before surgery. This includes a registered dietitian, a psychiatric specialist, a social worker, an anesthetist, the nursing and surgical teams, and the primary care provider. This approach has been shown to improve patient outcomes and reduce the risk of major postoperative complications.[25][26] The procedure requires an anesthesiologist, a bariatric surgeon, a scrub nurse, a surgical technician, and a resident or first assistant.

Preparation

The preoperative evaluation should be a multidisciplinary approach that includes a team of dieticians, psychologists, endocrinologists, anesthesiologists, nurses, physician extenders, cardiologists, and the surgeon.[26]

Psychological Evaluation

Patients must be psychologically fit to undergo bariatric surgery. This will help avoid major postoperative complications.[26] Patients need to be evaluated for psychological disorders such as depression, anxiety, and eating disorders. A patient's support system should be evaluated. They should also be evaluated for substance misuse disorders, such as alcohol or drug use. If they have alcohol dependence, they will need rehabilitation before planning the procedure. If the patient is smoking, smoking cessation should be encouraged before proceeding with the operation. Smoking significantly increases the risk of organ space infection, prolonged intubation, reintubation, pneumonia, sepsis, shock, and a longer length of stay in all patients undergoing bariatric surgery.[27] Smoking cessation will improve outcomes.

Nutritional Evaluation and Planning 

The nutritional evaluation includes assessment and education to guide the patient toward dietary changes needed after surgery. Patients are typically placed on a low-carbohydrate diet before surgery to shrink the liver as much as possible. Studies have shown that preoperative weight loss may improve postoperative outcomes and reduce complications. Patients who lose weight before surgery have been shown to experience greater total weight loss after surgery.[28] Weight-maintenance strategies should be discussed with patients during their nutritional evaluation, and the importance of glycemic control for patients with diabetes should also be emphasized.

Medical Clearance

As with all surgeries, medical evaluation and clearance are extremely important in the preoperative period. Patients must have a detailed history and physical, a thorough review of their prior surgeries, and a review of their past medical history. Recent laboratory studies should be performed. Patients' functional status must be determined, and if there is concern, a cardiologist may be warranted to perform a further workup. Patients who have obstructive sleep apnea need to be evaluated with a sleep study and a pulmonologist before surgery. Untreated obstructive sleep apnea can put the patient at increased perioperative risk for complications.[29]

Preoperative Imaging

Currently, there is no consensus on the imaging modalities to obtain before a bariatric procedure. Several studies have evaluated the use of abdominal ultrasounds to evaluate liver pathology, size, and cholelithiasis. Imaging was shown not to change patient outcomes and only increase healthcare costs.[30][31]

Other Preoperative Evaluation

Esophagogastroduodenoscopy (EGD) before bariatric surgery remains controversial. Some recommend a preoperative evaluation with EGD before restrictive procedures such as sleeve gastrectomy or adjustable gastric banding. These restrictive procedures may place these patients at a greater risk of worsening gastroesophageal reflux and Barrett's esophagus. Bypass procedures, such as Roux-en-Y gastric bypass, will result in an inaccessible foregut, making further evaluation of the upper GI tract difficult.[32] The current recommendations are that an EGD preoperatively should be performed on an individualized basis and in patients with significant GI symptoms.[33][34]

Technique or Treatment

Preparation and Patient Positioning

Patients are placed under general anesthesia. Intravenous preoperative antibiotics and thromboprophylaxis are administered before the procedure begins. Patients are placed in the supine position with the legs in a split position. Both arms are out to the side. The patient will be secured with straps and tape to prevent movement during table positioning. Sequential compression devices will be placed on the patient's legs. The patient will then be prepped and draped in a sterile fashion. 

Entrance

A 15-cm Veress needle is introduced at Palmer point (left subcostal area) to create a 15-mm Hg pneumoperitoneum. A 5- or 10-mm optical trocar is placed under direct vision 2 fingerbreadths below the xiphoid process for the camera. A 12-mm port is placed on each flank. A 5-mm port is placed at the epigastrium for the liver retractor. A 5mm port is placed in the left upper and left lower quadrants.

Mobilization of the Stomach and Duodenal Dissection

Dissection begins by opening the gastrocolic ligament at the level of the gastric body. This is done using an ultrasonic scalpel. The greater curvature of the stomach is then mobilized from the antrum to the angle of His. In super obese patients who have short mesentery and adhesions, sleeve gastrectomy may be performed as a first-stage operation.[35][36]

The pylorus is then identified and dissected free. The peritoneum is opened at the inferior and superior edges of the duodenum. The patient's antrum will be pulled to the left to better visualize the duodenum. The common bile duct will be identified on the superior aspect of the duodenum. This can be used as a landmark for further dissection. The inferior or posterior approach can then mobilize the duodenum. For the inferior approach, the gastrocolic ligament is divided using the harmonic scalpel. The pyloric artery is controlled. A posterior dissection is continued for the first 3 to 4 cm of the duodenum. The gastroduodenal artery is a marker for the limit of the posterior dissection. The duodenum will be divided at this point using a 60-mm linear stapler.

In the posterior approach, a window is created 3 to 4 cm distal to the pylorus. Blunt dissection is performed to find the plane between the duodenal wall and the pancreas. Careful dissection is required to avoid small venous branches to the pancreatic head from the gastroduodenal artery. After being fully mobilized, the duodenum will be divided using a 60-mm linear stapler at the first portion of the duodenum proximal to the gastroduodenal artery.[35]

Sleeve Gastrectomy

Gastric transsection is started from 5 to 7 cm from the pylorus. A linear stapler with 60-mm loads is used—the gastric transfection proceeds towards the fundus. A 32 to 40 French esophagogastric bougie is usually placed for guidance. Hemostasis on the staple line is controlled using clips or a 3-0 absorbable suture. The gastrectomy specimen is placed in a plastic bag and removed through one of the 12-mm trocars.

Small Bowel Transection

The patient is placed in the Trendelenburg position with the left side down. The ileocecal junction is identified, and any intrabdominal adhesions between the ascending colon and greater omentum are divided. The length of the metallic part of the laparoscopic bowel graspers (5 cm) is used to measure the alimentary limb. The small bowel is measured 100 cm from the ileocecal junction. Then, the small bowel is run another 150 cm and transected at that level using a 60-mm linear stapler. The small bowel mesentery may be opened by a few centimeters to reduce tension on the duodenal anastomosis.[35]

Duodenoileal Anastomosis

The alimentary limb is brought to the right upper quadrant in an antecolic fashion and brought to the transected portion of the duodenum. The omentum is mobilized from the ascending colon to relieve tension on the anastomosis. A hand-sewn or stapled end-to-side anastomosis is created. The anastomosis can be tested by insufflating air through the nasogastric tube. Repair sutures can be placed if there is a leak.

Ileoileal Anastomosis

The ileoileal anastomosis is then created at 100 cm from the ileocecal valve. Following the completion of the anastomosis, the mesenteric window (Petersen window) is closed to prevent an internal hernia. After this has been completed, a routine cholecystectomy and liver biopsy may be performed if warranted.[37]

Skin Closure

The trocars are then removed, and the abdominal fascia is closed at the larger port sites. The skin is then closed with absorbable sutures, and topical skin adhesive or sterile dressings are applied.

Complications

As with many surgeries, biliopancreatic diversion with duodenal switch complications can be divided into early and late complications. Common early complications include anastomotic leak and hemorrhage; common late complications include nutritional deficiencies.

Anastomotic Leak

The incidence of a gastric or duodenal leak following biliopancreatic diversion with duodenal switch is 1.14%, compared with 1.12% for Roux-en-Y gastric bypass.[38] The leak site appears to be more common at the duodenoduodenal anastomosis.[39] The risk of leakage from the longitudinal gastric staple line is minimal compared to the leak rate from the gastric staple line in the gastric bypass procedure. These patients may be asymptomatic, but they frequently present with tachycardia, which is usually the first sign. They can also have tachypnea and be febrile. The diagnostic test of choice for an anastomotic leak should be a computed tomography (CT) scan with oral and intravenous contrast, high sensitivity, and specificity. An upper GI series can also be used, but it has a low sensitivity. If the leak is acute (<5 days), they should return to the operating room for exploration, repair, and placement of a distal feeding tube.[40]

Hemorrhage

The reported incidence of a postoperative hemorrhage is less than 1% of all gastric bypass surgeries, which experience bleeding that requires intervention or transfusion. This can present as intraluminal and extraluminal bleeding. This has likely improved due to improved staple technology. Hemorrhage is more commonly seen with laparoscopic gastric bypass over open procedures.[41] Postoperative hemorrhage is treated at the surgeon's discretion, depending on the patient's clinical picture. For intraluminal bleeding, endoscopic treatment may be necessary, but it is not very common. Patients who have extraluminal bleeding and are hemodynamically unstable and unresponsive to resuscitation will need to return to the operating room for exploration and repair.

Nutritional Deficiencies

Biliopancreatic diversion with duodenal switch is the one bariatric procedure associated with the greatest perioperative malnutrition and metabolic-related complications. All patients need to begin supplementation postoperatively. Common nutritional deficiencies include iron deficiency anemia, protein-calorie malnutrition, hypocalcemia, and deficiencies of the fat-soluble vitamins B1, B12, and folate. Close follow-up and laboratory studies are essential for these patients. If a nutritional deficiency is detected, dietary supplementation is extremely important.[42]

Clinical Significance

Biliopancreatic diversion with duodenal switch is among the most metabolically efficient and durable operations in the spectrum of bariatric and metabolic surgery. This procedure achieves the greatest mean excess weight loss and the highest rates of long-term diabetes remission among all bariatric procedures, while preserving the pylorus and maintaining more physiologic gastric emptying compared to the traditional biliopancreatic diversion.[43] The operation’s restrictive and malabsorptive mechanisms result in profound improvements in obesity-related comorbidities, including type 2 diabetes mellitus, hyperlipidemia, hypertension, and obstructive sleep apnea.[44] For patients with severe or refractory obesity, particularly those with BMI ≥50 kg/m², biliopancreatic diversion with duodenal switch provides a durable, evidence-based intervention when nonoperative management or less extensive bariatric procedures have failed to achieve adequate metabolic control.[45]

However, the clinical impact of biliopancreatic diversion with duodenal switch extends beyond technical success in the operating room. The procedure’s potential for protein-calorie malnutrition and fat-soluble vitamin deficiencies demands lifelong nutritional surveillance, structured supplementation, and strong patient adherence.[46] Outcomes are therefore closely tied to interprofessional coordination among surgeons, dietitians, pharmacists, and primary care providers. With appropriate patient selection, comprehensive preoperative counseling, and vigilant long-term follow-up, biliopancreatic diversion with duodenal switch can deliver sustained metabolic benefits with acceptable morbidity.[47] As modern practice shifts toward minimally invasive and robotic techniques, the operation remains a benchmark for the balance between efficacy and nutritional safety in bariatric metabolic surgery.

Enhancing Healthcare Team Outcomes

Interprofessional collaboration is essential throughout the continuum of care. The surgeons coordinate preoperative evaluation, risk stratification, and patient education. Anesthesiologists contribute to safe induction and airway management in patients with obesity and related comorbidities. Specialty nurses provide perioperative monitoring, wound care, and reinforce lifestyle and nutrition teaching. Registered dietitians guide individualized dietary progression and micronutrient supplementation to prevent protein-calorie and vitamin deficiencies. Pharmacists review medications for altered absorption and adjust dosing of antihypertensive, diabetic, and anticoagulant therapies. Psychologists and social workers evaluate readiness for behavior change, identify barriers to adherence, and support mental health. Physical and occupational therapists aid in early mobilization and reinforce long-term activity plans to sustain weight loss. Clear, structured communication via multidisciplinary rounds, standardized order sets, and shared electronic documentation will enhance situational awareness, reduce errors, and ensure patient-centered care.  

A culture of team accountability and ethical practice underpins every phase: ensuring informed consent is truly informed, addressing postoperative complications promptly, and maintaining transparency regarding risks of malabsorption and the lifelong commitment required. High-functioning bariatric programs emphasize regular multidisciplinary conferences, longitudinal follow-up clinics, and quality-tracking registries to optimize outcomes and continually improve team performance.[46] Ultimately, effective collaboration across specialties transforms the complex biliopancreatic diversion with duodenal switch pathway into a safe, patient-centered model of surgical metabolic care.