Duodenal switch also known as “biliopancreatic diversion with duodenal switch (BPD-DS)” is the most complex and costly bariatric surgery. It is often done as a revision surgery when other bariatric surgeries have failed, but may also be done as a primary bariatric procedure. Duodenal switch is also the most effective bariatric surgery as it combines both restrictive and malabsorptive procedures. Complications are therefore enormous and mortality is high, stemming from the complexity of the operation.
The restrictive component of duodenal switch involves a gastric sleeve surgery which reduces the stomach capacity by 80-90%. The malabsorptive component includes re-fashioning of the small intestinal anatomy in a way that brings the bile and pancreatic enzymes in contact with the food at the distal end of the small intestine. This significantly reduces the amount of absorbable nutrients, as longer portion of small intestine where absorption occurs has been bypassed. A third component of duodenal switch is the removal of gallbladder (cholecystectomy), done to prevent gallstone that often accompanies rapid weight loss in these patients.
The complications of BPD-DS are therefore those of gastric sleeve surgery combined with complications from the anastomotic sites and malabsorption. Complications from the gastric sleeve components include leakage from staple line, gastroesophageal reflux disease, bleeding from the staple line, intra-abdominal abscess, stricture, hair loss, etc. Complications from anastomotic sites include leakage from anastomotic sites, stricture around the anastomotic site, intestinal obstruction, ulcers, etc. Other complications include deep vein thrombosis with pulmonary embolism, steatorrhea, wound infection and halitosis.
Nutritional deficiency is one of the major complications of duodenal switch. This is sequel to reduction in the effective absorptive surface. Micronutrients such as iron, vitamin B12, vitamin B1, folate, zinc, calcium, and all the fat soluble vitamins (vitamins A, D, E and K) may all be affected. Patient may therefore suffer from iron deficiency or megaloblastic anemia, osteomalacia, osteoporosis and bleeding problems. Protein-energy malnutrition may also occur due to poor absorption.
Leakage from staple line following duodenal switch can occur from the staple line along the line of resection of the stomach or at the site of small intestinal anastomoses. This may result in peritonitis with abdominal pain and tenderness, abdominal distension, fever, increased heart rate and respiratory rate, hypotension and some patients may go into shock. It often requires surgical re-exploration to repair the leakage site and clean the peritoneum.
Gastroesophageal reflux disease, manifested as heartburn that is worse on lying down, is a common problem in morbidly obese individuals. This may however get worse after BPD-DS. It is a complication of gastric sleeve surgery: the restrictive component of BPD-DS. Heartburn may also develop in those that did not have the symptoms prior to surgery. Treatment is often with antacids and drugs that reduce gastric acid secretion.
Bleeding from staple line may be intraluminal or extraluminal. Intraluminal bleeding will present with hematemesis (vomiting of blood) or melena (passage of dark shinning stool) while extraluminal bleeding will present with features of peritonitis or shock. Other sources of extraluminal bleeding include abdominal wall (port sites), injured spleen and liver. Bleeding often requires an aggressive resuscitation and prompt definitive intervention to prevent shock and irreversible multiple organ damage.
Stricture may occur at the incisura angularis along the lesser curvature of the stomach or at the site of the intestinal anastomosis. The presentation includes difficulty with swallowing, nausea, vomiting, and abdominal pain. Treatment is conservative in the case of gastric stricture that presents early while balloon dilatation and/or open surgery are the treatments for late presentation and small intestinal stricture.
Intestinal obstruction after BPD-DS is secondary to internal hernias but may rarely be due to adhesion of bowel loops by fibrotic bands. The refashioning of the small intestine may create potential spaces into which bowel loops may herniate. Clinical features include abdominal pain and tenderness, abdominal distension, vomiting, constipation, features of shock. Treatment is by resuscitation and conservative management but surgical exploration may be indicated is some group of patients.
Hair loss (alopecia) is one of the complications of BPD-DS that results from a condition referred to as telogen effluvium (shedding of large amount of hairs due to simultaneous entry into the resting phase). It is a manifestation of protein and micronutrients (e.g. zinc) deficiency. Although the condition is temporary and often resolves within 3-6 months, the psychological effect it has on the patient makes it a significant complication.
Steatorrhea is the passage of pale, bulky, foul smelling feces that floats in water. It is due to the presence of abnormal fat contents in the stool. Steatorrhea is one of the manifestations of malabsorption following BPD-DS as most of the dietary fats are not absorbed owing to a relative deficiency of bile.
Wound infection may occur after duodenal switch. The port sites are points in the anterior abdominal wall where endoscopic equipment is introduced into the abdominal cavity. Infection of these sites may manifest in the form of undue pain, tenderness, fever, and discharge of pus. Treatment is by sepsis work up with appropriate antibiotics and wound dressing. However, if complicated by an intra-abdominal abscess, a surgical exploration for drainage may be indicated.
In conclusion, duodenal switch (BPD-DS) is the most effective, most costly, and most complicated bariatric surgery that can be done as a primary procedure or as a revision surgery for other weight loss surgeries. It has the highest rate of complications. However, some of these complications can be prevented and the unpreventable ones can be effectively managed if diagnosed early.