eMedicine Specialties > Gastroenterology > Stomach

Dumping Syndrome

Author: Alan BR Thomson, MD, MSc, PhD, Professor, Department of Medicine, Division of Gastroenterology, University of Alberta Faculty of Medicine
Coauthor(s): Sukhdeep Padda, MD, Assistant Professor, Department of Internal Medicine, Section of Gastroenterology, University of Arizona Health Sciences Center; Francisco Ramirez, MD, FACG, Chief, Section of Gastroenterology, Carl T Hayden VA Medical Center; Associate Professor, Department of Medicine, University of Arizona; Thomas Aguirre, MD, Gastroenterology Fellow, Department of Internal Medicine, University of Arizona
Contributor Information and Disclosures

Updated: Jun 10, 2008

Introduction

Background

The stomach serves as the receptive and storage site of ingested food. The primary functions of the stomach are to act as a reservoir, to initiate the digestive process, and to release its contents downstream into the duodenum in a controlled fashion. The capacity of the stomach in adults is approximately 1.5-2 liters, and its location in the abdomen allows for considerable distensibility. Gastric motility is regulated by the enteric nervous system, which is influenced by extrinsic innervation and by circulating hormones. Alterations in gastric anatomy after surgery or interference in its extrinsic innervation (vagotomy) may have profound effects on gastric emptying. These effects, for convenience, have been termed postgastrectomy syndromes.

Postgastrectomy syndromes include small capacity, dumping, bile gastritis, afferent loop syndrome, efferent loop syndrome, anemia, and metabolic bone disease.

Pathophysiology

Clinically significant dumping syndrome occurs in approximately 10% of patients after gastric surgery.  Dumping syndrome has characteristic alimentary and systemic manifestations. It is the most common and often disabling postprandial syndrome observed after a variety of gastric surgical procedures, such as vagotomy, pyloroplasty, gastrojejunostomy, and laparoscopic Nissan fundoplication. Dumping syndrome can be separated into early and late forms depending on the occurrence of symptoms in relation to the time elapsed after a meal. Both forms occur because of rapid delivery of large amounts of osmotically active solids and liquids into the duodenum. Dumping syndrome is the direct result of alterations in the storage function of the stomach and/or the pyloric emptying mechanism.

Azpiroz and Malagelada have shown that the accommodation response and the phasic contractility of the stomach in response to distention are abolished after vagotomy or partial gastric resection.¹ This probably accounts for the immediate transfer of ingested contents into the duodenum. Hertz made the association between postprandial symptoms and gastroenterostomy in 1913.² Hertz stated that the condition was due to "too rapid drainage of the stomach."² Mix first used the term dumping in 1922.³ Mix observed radiographically the presence of rapid gastric emptying in patients with vasomotor and GI symptoms.³

The severity of dumping syndrome is proportional to the rate of gastric emptying. Postprandially, the function of the stomach is to store food and to allow the initial chemical digestion by acid and proteases before transferring food to the gastric antrum. In the antrum, high-amplitude contractions triturate the solids, reducing the particle size to 1-2 mm. Once solids have been reduced to the desired size, they are able to pass through the pylorus. An intact pylorus prevents the passage of larger particles into the duodenum. Gastric emptying is controlled by fundic tone, antropyloric mechanisms, and duodenal feedback. Gastric surgery alters these mechanisms in several ways.

Gastric resection can reduce the fundic reservoir, thereby reducing the stomach's receptiveness to a meal. Similarly, vagotomy increases gastric tone, limiting accommodation. An operation in which the pylorus is removed, bypassed, or destroyed increases the rate of gastric emptying. Duodenal feedback inhibition of gastric emptying is lost after a bypass procedure, such as gastrojejunostomy. Accelerated gastric emptying of liquids is a characteristic feature and a critical step in the pathogenesis of dumping syndrome. Gastric mucosal function is altered by surgery, and acid and enzymatic secretions are decreased. Also, hormonal secretions that sustain the gastric phase of digestion are affected adversely. All these factors interplay in the pathophysiology of dumping syndrome.

Early dumping

Symptoms of early dumping syndrome (30-60 min postprandial) are believed to result from accelerated gastric emptying of hyperosmolar contents into the small bowel. This leads to fluid shifts from the intravascular compartment into the bowel lumen, resulting in rapid small bowel distention and an increase in the frequency of bowel contractions. Rapid instillation of liquid meals into the small bowel has been shown to induce dumping symptoms in healthy individuals. Bowel distention may be responsible for GI symptoms, such as crampy abdominal pain, bloating, and diarrhea. Intravascular volume contraction due to osmotic fluid shifts is perhaps responsible for vasomotor symptoms, such as tachycardia and lightheadedness.

This hypothesis has been questioned for several reasons. First, the severity of dumping is not reliably related to the volume of hypertonic solution ingested. Second, intravenous infusion sufficient to prevent the postprandial fall in plasma volume may not abolish the dumping symptoms. Furthermore, Kalser and Cohen measured intrajejunal osmolarity and glucose content using a continuous perfusion method.⁴ They found that the degree of dilution of the hyperosmolar glucose in patients postgastrectomy was similar in symptomatic and asymptomatic subjects.

Provocation with oral glucose in patients with early dumping generally provokes an increase in heart rate. Although vasoconstriction is expected in a volume-contracted state, patients with dumping syndrome have vasodilation, first reported by Hinshaw et al.⁵ Vasodilatation has been demonstrated by some investigators, but not by others. An increase in blood flow to the superior mesenteric artery has been described in patients with dumping syndrome. This peripheral and splanchnic vasodilatory response seems to be pivotal in the pathogenesis of dumping.

In experimentally induced dumping in dogs, symptoms can be induced in a healthy animal by transfusion of portal vein blood. This led to the hypothesis that humoral factors may have an important role in the pathogenesis of dumping. Some evidence indicates that serotonin and the kallikrein-kinin system may be involved, but this evidence is not impressive.

Postprandial release of gut hormones, such as enteroglucagon, peptide YY, pancreatic polypeptide, vasoactive intestinal polypeptide, glucagonlike peptide-1 (GLP-1), and neurotensin, is higher in patients with dumping syndrome compared to asymptomatic patients after gastric surgery. Some or all of these peptides are likely to participate in the pathogenesis of dumping syndrome. One of the effects of these hormones is the retardation of proximal GI motility and the inhibition of secretion. This function is called the ileal brake. Some authors have suggested that the accelerated release of these hormones is an attempt to activate the ileal brake, thereby delaying proximal transit time in response to rapid delivery of food to the distal small bowel.

Late dumping

Late dumping occurs 1-3 hours after a meal. Rapid delivery of a meal to the small intestine results in an initial high concentration of carbohydrates in the proximal small bowel and rapid absorption of glucose. This is countered by a hyperinsulinemic response. The high insulin levels are responsible for the subsequent hypoglycemia. Holdsworth et al showed that intrajejunal glucose induces a higher insulin release than intravenous infusion of glucose.⁶ The serum glucose levels were the same in both experiments. This effect of enhanced insulin release after an enteral glucose load as compared to intravenous glucose administration is called the incretin effect.

Two hormones are thought to play a pivotal role. These are glucose-dependent insulinotropic peptide and GLP-1. In human studies, an increase in GLP-1 response has been noted after an oral glucose challenge. An increased GLP-1 response has been noted in patients after total gastrectomy, esophageal resection, and partial gastrectomy. Furthermore, a positive correlation was found between the rise in plasma GLP-1 and insulin release. Exaggerated GLP-1 response likely plays an important role in the hyperinsulinemia and hypoglycemia in patients with late dumping. The reason why some patients remain asymptomatic after gastric surgery, while others develop severe symptoms, remains elusive.

Frequency

United States

Incidence and severity of symptoms in dumping syndrome are related directly to the extent of gastric surgery. An estimated 25-50% of all patients who have undergone gastric surgery have some symptoms of dumping. However, only 1-5% are reported to have severe disabling symptoms. Incidence of significant dumping has been reported to be 6-14% in patients after truncal vagotomy and drainage and from 14-20% in patients after partial gastrectomy. Incidence of dumping syndrome after proximal gastric vagotomy without any drainage procedure is less than 2%. In the pediatric population, dumping syndrome is described almost exclusively in children who have undergone Nissen fundoplication.

Changes in the need for elective gastric surgery have led to a decline in the frequency of postgastrectomy syndromes. A 10-fold reduction has occurred in elective operations for peptic ulcer disease in the last 20-30 years. Although this trend preceded the advent of histamine-2 receptor antagonists, these drugs and proton pump inhibitors have accelerated the decline. Helicobacter pylori treatment and eradication in patients with peptic ulcer disease have further decreased the need for surgery. Newer gastric operations, such as proximal gastric vagotomy (which produces minimal disturbance of gastric emptying mechanisms), are associated with a much lower incidence of postgastrectomy syndromes.

Although the need for elective surgery for peptic ulcer disease has declined, the need for emergency surgery has remained the same over the last 20 years. Emergency surgery tends to be more mutilating to the stomach. This increases the incidence of more severe symptoms.

Sex

A female preponderance exists for the incidence of postgastrectomy syndromes.

Clinical

History

The clinical presentation of dumping syndrome can be divided into GI symptoms and vasomotor symptoms. GI symptoms include early satiety, crampy abdominal pain, nausea, vomiting, and explosive diarrhea. Vasomotor symptoms include diaphoresis, flushing, dizziness, palpitations, and an intense desire to lie down.

The expression of these symptoms varies in different individuals. Most patients with early dumping have both GI and vasomotor symptoms, while patients with late dumping have mostly vasomotor symptoms. Patients with severe dumping often limit their food intake to avoid symptoms. This leads to weight loss and, over time, malnutrition.

• Early dumping systemic symptoms
  • Desire to lie down
  • Palpitations
  • Fatigue
  • Faintness
  • Syncope
  • Diaphoresis
  • Headache
  • Flushing
• Early dumping abdominal symptoms
  • Epigastric fullness
  • Diarrhea
  • Nausea
  • Abdominal cramps
  • Borborygmi
• Late dumping
  • Perspiration
  • Shakiness
  • Difficulty to concentrate
  • Decreased consciousness
  • Hunger

Physical

• Dumping syndrome is diagnosed based on typical symptoms in patients who have undergone gastric surgery. Signs and symptoms can be elicited with the glucose challenge test.
• Sigstad developed a diagnostic scoring system on weighing factors allocated to the symptoms of dumping. A diagnostic index greater than 7 is suggestive of dumping syndrome.
• Sigstad's diagnostic index, indicating symptoms and the points assigned for those symptoms, is as follows:
  • Shock - +5
  • Almost fainting, syncope, unconsciousness - +4
  • Desire to lie or sit down - +4
  • Breathlessness, dyspnea - +3
  • Weakness, exhaustion - +3
  • Sleepiness, drowsiness, yawning, apathy, falling asleep - +3
  • Palpitation - +3
  • Restlessness - +2
  • Dizziness - +2
  • Headaches - +1
  • Feeling of warmth, sweating, pallor, clammy skin - +1
  • Nausea - +1
  • Fullness in the abdomen, meteorism - +1
  • Borborygmus - +1
  • Eructation - -1
  • Vomiting - -4
• The Visick classification is also used to characterize the severity of symptoms after gastric surgery. A rise in the heart rate by 10 beats per minute or more in the first hour after an oral glucose challenge of 50 g was found to be 100% sensitive and 92% specific for early dumping.

Causes

• Dumping can be separated into early and late forms depending on the occurrence of symptoms in relation to the time elapsed after a meal. Both forms occur because of the rapid delivery of large amounts of osmotically active solids and liquids to the duodenum. This is a direct result of alterations in the storage function of the stomach and/or pyloric emptying mechanism.
• The severity of dumping syndrome is proportional to the rate of gastric emptying.
  • Postprandially, the stomach assumes its reservoir function to allow initial chemical digestion by acid and proteases before transferring food to the antrum. In the antrum, high-amplitude contractions triturate solids.
  • Once solids have been reduced to 1-2 mm, they are able to empty through the pylorus. An intact pylorus has a separating function that prevents the passage of larger particles into the duodenum.
  • Gastric emptying is controlled by fundic tone, antropyloric mechanisms, and duodenal feedback. Gastric surgery alters these mechanisms in several ways.
• Gastric resection can reduce the fundic reservoir, thereby reducing the receptiveness of the stomach to a meal. Similarly, vagotomy increases gastric tone, limiting accommodation.
• Any operation in which the pylorus is removed, bypassed, or destroyed increases the rate of gastric emptying. Duodenal feedback inhibition of gastric emptying is also lost after bypass of the duodenum with gastrojejunostomy. Accelerated early gastric emptying of liquids is a characteristic feature and a critical step in the pathogenesis of dumping syndrome.
• Gastric mucosal function is altered by surgery, and acid and enzymatic secretions are decreased. Also, hormonal secretions that sustain the gastric phase of digestion are adversely affected.

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