Gastric outlet obstruction (GOO), which is also called pyloric obstruction, is a medical emergency that refers to the mechanical blockage of the outlet of the stomach which results in delayed gastric emptying of the stomach contents. Gastric outlet obstruction is however, not a disease standing on its own. It is the result of other clinical pathological conditions, more like a complication of some other disease that affect the stomach or nearby structures of the stomach.
The stomach is an organ of the digestive system whose primary purpose is to store food. It is attached to the esophagus from the top and exits into the small intestine (duodenum). The stomach is divided into four parts namely – the cardia, the fundus, the body and the pylorus. The pylorus is what is called the gastric outlet (into the duodenum) where the obstruction can occur.
When an obstruction occurs, food can no longer pass into the intestine which accumulates in the stomach and leads to persistent vomiting and dehydration. The patient loses appetite for food and appears malnourished with weight loss.
Epidemiological studies on gastric outlet obstructions is not very much available but the studies show a decline in the incidence of the condition. Peptic ulcer disease had been the leading cause of gastric outlet obstructions in the past, but the case is different now since the discovery of better treatment measures. Only about 2-5% of PUD patients might develop gastric outlet obstructions. Malignancies especially pancreatic cancer, are now the leading causes of the condition. 10-20% of patients with pancreatic cancer are likely to develop gastric outlet obstructions. Pyloric stenosis is the leading cause of GOO in children which affects males more than females.
What Causes Gastric Outlet Obstruction?
Gastric outlet obstruction can be from either an intrinsic or extrinsic cause. Intrinsic causes of obstruction are those pathological conditions that are from within the stomach or duodenum which results in the inflammation, scarring, fibrosis or edema of the gastric outlet resulting in a partial or complete obstruction. The extrinsic causes are pathological conditions of nearby structures like pancreas and gall bladder that compress the gastric outlet from outside which brings about the obstruction. It is important to note this when diagnosing gastric outlet obstructions.
In addition to whether the cause of the obstruction is intrinsic or extrinsic, the causes of gastric outlet obstructions are divided into two : Benign and malignant.
Benign causes of gastric outlet obstruction include
- Peptic ulcer disease (PUD)
- Gastric polyps
- Obstruction from gall stones (Boveret’s Syndrome)
- Pyloric stenosis
- Congenital duodenal web
- Pyloric mucosal diaphragm
- Ingestion of caustic substances
- Pancreatic pseudocyst
The malignant causes include
- Gastric cancer
- Pancreatic cancer
- Ampullary cancer
- Duodenal cancer
- Cholangiocarcinoma (gall bladder cancer)
Signs and symptoms of Gastric Outlet Obstruction
The presence or severity of the signs and symptoms depends on whether there is a partial or complete obstruction of the pylorus. They include
- Vomiting (which is the cardinal symptom) which contains food content
- Weight loss
- Signs of dehydration
- Visible peristalsis
- Succession splash (splash-like sound when you shake the patient’s abdomen)
- Increased bowel sounds
- Abdominal tenderness may or may not be present depending on the underlying cause.
How Gastric Outlet Obstruction is Diagnosed
The signs and symptoms mentioned above mimics that of other gastrointestinal conditions. Diagnosing gastric outlet obstruction involves additional investigations when suspected to determine the underlying cause.
An upper gastrointestinal endoscopy is the confirmatory diagnostic tool for gastric outlet obstruction. A Barium swallow test can also be used in addition. Abdominal X-rays can help show the gastric fluid levels.
The most important laboratory tests are blood urea and nitrogen (BUN) and electrolytes to ascertain hypochloremia and hypokalaemia (low chlorine and potassium blood levels) as a result of the dehydration caused by vomiting.
Management of Gastric Outlet Obstruction
The general measures taken for the management of gastric outlet obstruction include
- Admission of the patient
- Passing naso-gastric tube (N-G tube) to decompress the stomach
- Rehydration of the patient with intravenous fluids
- Correction of any electrolyte imbalance
The actual treatment of gastric outlet obstruction is focused on the underlying cause of the obstruction. There are medical and surgical interventions available which include
- Medical treatment for PUD and H. Pylori with antibiotics and H-2 receptor blockers.
- Endoscopic balloon dilatation of the pylorus.
- Surgical procedures like vagotomy, antrectomy, pyloroplasty, gastojejunostomy and laparatomy.
The important complications of gastric outlet obstruction to prevent are stomach perforation, malnutrition, dehydration and electrolyte imbalance. Early diagnosis and treatment of the condition will result in good prognosis or outcomes.