Duodenal switch


The duodenal switch is a surgical procedure designed to promote weight loss by altering the structure of both the stomach and small intestine. It involves a gastrectomy, where a portion of the stomach is removed, and an intestinal bypass that shortens the path food takes through the intestines. This dual approach restricts the stomach’s capacity to hold food and decreases the small intestine’s ability to absorb nutrients, categorizing it as a “malabsorptive” procedure. Additionally, it suppresses the production of hunger hormones normally released by the stomach and small intestine.

There are currently two main types of duodenal switch procedures in practice. The original method, known as the biliopancreatic diversion with duodenal switch or gastric reduction duodenal switch, has a longer history and more extensive research supporting its efficacy. In contrast, the loop duodenal switch is a newer variation developed to simplify the surgical process and reduce potential complications associated with the original technique.

Reasons for undergoing the procedure

Healthcare providers may suggest bariatric surgery for individuals with severe obesity (class III), characterized by a BMI of 40 or higher, or a BMI of 35 with obesity-related diseases like hypertension, high cholesterol, or elevated blood sugar. Duodenal switch surgery might be recommended for those with a BMI of 50 or higher, or severe obesity-related conditions. This procedure offers the most significant weight loss and improves metabolic syndromes such as Type 2 diabetes but carries a higher risk of complications. Despite these risks, for individuals with severe conditions, the potential benefits often outweigh the risks associated with the surgery.

Obesity significantly increases the risk of various diseases across multiple body systems. Duodenal switch surgery effectively reduces this risk and mitigates the onset and impact of these conditions, including:

  • Cardiovascular diseases:
    • Hypertension
    • Arterial disease
    • Vascular disease
    • Heart attack
    • Stroke
  • Respiratory diseases:
    • Asthma
    • Obstructive sleep apnea
    • Obesity hypoventilation syndrome
  • Metabolic diseases:
    • Hyperlipidemia
    • Insulin resistance and diabetes
  • Gastrointestinal diseases:
    • Nonalcoholic fatty liver disease
    • Nonalcoholic steatohepatitis
  • Reproductive diseases:
    • Polycystic ovary syndrome (PCOS)
    • Infertility
  • Musculoskeletal issues:
    • Back strain
    • Weight-bearing osteoarthritis
  • Cancer:
    • Especially colorectal cancer and liver cancer


The risks of duodenal switch surgery are similar to those of any other abdominal surgery and can include:

  • Wound infection
  • Excessive bleeding
  • Reactions to anesthesia
  • Blood clots

Complications more specific to gastric bypass surgery include:

  • Hernias: Organs pushing through gaps in the muscle wall.
  • Small bowel obstruction: Scar tissue causing narrowing or blockage of the small intestine.
  • Anastomotic leaks: Leakage at the surgical connection points in the intestine, leading to serious infections.

Long-term complications or side effects
After duodenal switch surgery, possible long-term complications or side effects include:

  • Malnutrition: Due to reduced nutrient absorption, requiring lifelong nutritional supplements and monitoring for deficiencies.
  • Diarrhea: Resulting from decreased food digestion and water absorption in the small intestine.
  • Bile reflux: Possible when surgery affects the pyloric valve, causing bile to flow back into the stomach, potentially leading to gastritis and ulcers.
  • Gallstones: Rapid weight loss can lead to cholesterol buildup in the gallbladder, increasing the risk of gallstone formation.

These risks are manageable with proper medical supervision and adjustments to diet and lifestyle post-surgery.

Before the procedure

If your healthcare provider determines you’re a suitable candidate for surgery, you’ll undergo a comprehensive screening process. This typically includes standard medical tests to ensure your overall health is optimal for surgery. Additionally, there will be assessments for alcohol, tobacco, and drug use, with support offered to help you quit if needed. Psychological screening or counseling may also be part of the process to assess your readiness for the significant lifestyle changes and the discipline required after the surgery. It’s essential to demonstrate that you’ve attempted and struggled with other weight loss methods before proceeding with surgery. Engaging in a seminar focused on bariatric surgery ensures you fully understand the procedure and its implications.

Once you’ve met these requirements and scheduled your surgery, your healthcare provider will guide you through a preoperative diet for several weeks. This phase aims to facilitate a slight weight loss before the procedure, enhancing its safety and optimizing your body for surgery.

During the procedure

The duodenal switch surgery can be performed either as a traditional open surgery or laparoscopically, with the latter being less invasive. Laparoscopic surgery involves using narrow tools through small “keyhole” incisions rather than opening the entire abdominal cavity. Surgeons and patients often prefer this minimally invasive approach when feasible, though some cases may require open surgery based on individual health needs. Occasionally, a procedure started laparoscopically may need to convert to open surgery.

The duodenal switch is a two-step procedure. Initially, it begins with a sleeve gastrectomy, where about 65% of the stomach is removed. While some individuals undergo sleeve gastrectomy alone, it serves as the initial step in a duodenal switch. The subsequent step involves intestinal bypass, which can occur either during the same surgery or as a separate procedure later, based on safety considerations for the patient.

There are two methods for performing the duodenal switch: the original (biliopancreatic diversion) and the modified (loop) duodenal switch. The primary difference lies in the intestinal bypass phase. Both methods start by dividing the small intestine near the duodenum and then connecting a lower segment to the top, bypassing the middle. This “switches” the duodenum with a lower portion of the small intestine.

In the original duodenal switch, approximately 80-90% of the small intestine is bypassed, significantly reducing nutrient absorption and promoting substantial weight loss, albeit with a higher risk of malnutrition. In contrast, the modified duodenal switch bypasses about 50-60% of the small intestine to mitigate this risk. Additionally, the original procedure involves two divisions and reconnections of the small intestine, while the modified version is simpler, involving only one.

These variations in approach allow surgeons to tailor the procedure based on individual patient needs and health considerations.

After the procedure

You will need frequent follow-up appointments with your doctor for the first one to two years, and periodic check-ups for the rest of your life. The most significant weight loss typically occurs during the initial two years, during which your doctor will closely monitor your progress and overall health. Lifelong regular blood tests will be necessary to check for nutritional deficiencies, and you will need to take daily nutritional supplements to prevent malnutrition.


It is likely that before you feel prepared to return to work, you will need to recover for a few days in the hospital and then a few weeks at home. Your body will undergo significant changes during your recuperation, including a quick loss of weight. Some transient symptoms that you might have during this time include hormonal changes, nausea, fatigue, hair loss, mood swings, feeling cold, or body pain.

Throughout your recuperation, you’ll also need to adhere to stringent dietary restrictions on both what and how you eat. This will allow your digestive system to recover and acclimate to the new circumstances. Each step of returning to a regular diet may take one to two weeks to complete, and they include clear liquids, full liquids, pureed, and soft diet.

Although each person’s weight loss journey is unique, there are some common patterns. The first three months following surgery are when weight loss is most rapid. You could anticipate to shed roughly thirty percent of your extra weight over this period. After that, weight loss somewhat slows down for the following three months. You might have dropped between 50% and 75% of your extra weight by the one-year milestone. After surgery, weight loss usually peaks between 12 and 18 months later. It could account for 75% to 85% of your extra weight.