Dumping syndrome is a condition where largely undigested foods rapidly bypass the stomach and proceed or get “dumped” into the small intestine. This is a common phenomenon seen in those who have undergone gastric, esophageal or bariatric surgery.
The rapid emptying of the gastric contents into the small intestine results in a fluid shift from the intravascular compartment to the intestinal lumen. This leads to a plethora of complications including cardiovascular, gastrointestinal (GI) and postprandial hypoglycemia. Dumping syndrome can be classified as early or late depending on when the symptoms occur in relation to the time elapsed after eating.
Early Dumping Syndrome
Early dumping syndrome (EDS) occurs between 30 to 60 minutes after a person has eaten. It has been long suggested that EDS symptoms happen due to hyperosmolar gastric content in the small intestinal lumen causing fluid to be pulled from the intravascular compartment into the small bowel lumen.
This fluid shift causes rapid distension of the small bowel, which leads to associated symptoms such as bloating, diarrhea, nausea and abdominal pain. There is also an increase in the number of bowel contractions. In addition to the GI symptoms, intravascular volume depletion causes lightheadedness and an increase in heart rate.
Late Dumping Syndrome
Late dumping syndrome (LDS) happens anywhere between 1 to 3 hours after a meal. LDS is believed to be due to an overwhelming increase in insulin secretion that leads to reactive hypoglycemia (i.e. low blood sugar level). The exaggerated rise of insulin occurs due to the rapid transit of carbohydrates to the small intestines and the subsequent quick absorption of this glucose.
To counter the effects of high glucose concentrations, the body secretes more insulin than usual (hyperinsulinemia) which remains for an extended period, causing hypoglycemia. The signs and symptoms that occur as a result of hypoglycemia include sweating, tremors, weakness, heart palpitations, nausea, dizziness, aggression, confusion and loss of consciousness.
Both EDS and LDS occur due to the dumping of osmotically active food particles into the small bowel lumen. The severity of either classifications is directly proportional to the rate at which the stomach empties. Under normal physiological conditions the stomach acts as a reservoir and allows for the thorough digestion of large food particles before their transition to the duodenum, the first part of the small intestine.
Digestion in the stomach is achieved through acid and proteases as well as mechanical action via high-amplitude contractions. Once particles have reached a size of 2 mm or less they are considered ready to pass through the pylorus of the stomach, which functions as a gatekeeper to block larger particles.
Emptying of the stomach is further controlled by tone of the fundus and pylorus and by duodenal feedback mechanisms. Any pathology or operation that affects any of the mechanisms responsible for digestion, the reservoir function of the stomach or its motor and/or emptying may result in EDS and/or LDS.