While restrictive procedures limit the amount of food, malabsorptive procedures limit the amount of energy absorbed from the foods ingested by bypassing some portion of the intestine.
Most malabsorptive procedures combine an intestinal bypass with a restrictive procedure. This method of restricting intake and absorption together has proven to be the most effective method of assuring long-term weight loss.
The BPD/DS is a primarily malabsorptive procedure. It involves a long, narrow sleeve gastrectomy, preserving the antrum and pyloric sphincter.
The duodenum is transected above the ampulla of Vater and the ileum is transected 250cm proximal to the ileocecal valve. The distal end of the transected ileum is anastomosed to the proximal end of the transected duodenum.
The proximal end of the transected ileum is then anastomosed to the distal ileum, 100cm from the ileocecal valve. With this operation, the common channel is usually only the distal 100cm of ileum.
The BPD/DS is associated with a mean loss of 85% of excess weight and with mortality of about 1.0%. The operation is associated with fat malabsorption and may cause protein-calorie malnutrition deficiencies in fat-soluble vitamins, iron and calcium, as well as foul-smelling stools associated with the steatorrhea.