Gastric outlet obstruction

Gastric outlet obstruction or GOO involves the inability of the stomach to move food into the small intestine. It is most commonly caused by gastric cancer and peptic ulcers but may be caused by a variety of other conditions as well.

Definition & Facts

Gastric outlet obstruction is a condition that impedes the stomach from being able to empty. Normally, the channel made up of the pylorus and duodenum allows the stomach to empty its contents into the small intestine. However, a variety of obstructions can arise that prevent this process from occurring, which in turn cause a number of serious health problems.

Benign causes of gastric outlet obstruction in adults are stomach polyps and peptic ulcers. In children, congenital duodenal webs and pyloric stenosis commonly cause the obstruction. Caustic ingestion of poisonous substances like acids and alkalines can cause the obstruction in people of any age.

Symptoms & Complaints

• Abnormal enlargement of the stomach (abdominal distension)
• Constipation
• Difficult and painful swallowing (dysphagia)
• Pain of the epigastrium. This is pain in the upper abdomen.
• Vomiting. Vomiting is a clinical symptom characteristic of GOO. It usually occurs immediately after eating. The vomit will appear green or yellow in color.
• Metabolic acidosis becomes a problem when there is a loss of electrolytes due to vomiting.
• Hypokalemia in which potassium levels are low in the blood due to persistent vomiting
• Unexplained weight loss caused by loss of appetite and fluid loss. Initially, patients tolerate liquids better than solid foods. Malnutrition, due to poor caloric intake, is a sign of severe illness.
• Satiety (that is, a feeling of fullness)
• Stool passage is painful and difficult due to hardened and dry feces.
• Hypertrophy of the pylorus.

Causes

The most common cause of GOO is peptic ulcers. Open sores form in the stomach wall or the duodenum. The affected area swells and narrows the passageway. Scar tissue forms in chronic cases, which results in localized narrowing. Additional causes include the following:

• Stomach polyps growing in the stomach wall. Usually, they are small and benign though larger polyps can potentially become cancerous.
• There is a link between gastric outlet obstruction and chronic gastritis.
• Duodenal webs. These occur where a part of the membrane of the duodenum creates an obstruction. These are rare and can be congenital.
• Gallstones. While rare, a large gallstone that is stuck in the first section of the duodenum or pylorus can cause a blockage.
• Pancreatic cysts that vary in size. Large pseudocysts are most likely to cause GOO. Pseudocysts are types of cysts that lack a cell wall or lining.
• Bezoars are indigestible foreign objects, hair, medication, or undigested food masses that stick in the pylorus of the stomach and cause obstruction.
• Ingestion of caustic substances can occur as a result of a suicide attempt or as an accident among children. Commonly ingested caustic substances include lye which is found in drain cleaner.

Diagnosis & Tests

A diagnosis relies on running a number of tests. A complete blood count will check for hematocrit and hemoglobin to detect anemia. The health care provider will obtain a basic metabolic panel in part to identify and correct electrolyte abnormalities that often occur. Liver function tests are helpful if the doctor suspects cancer. A test to check for the H. pylori infection, a type of bacterial infection may also be performed.

Various imaging studies will be performed. Computed tomography (CT) scans as well as an upper gastrointestinal series with the use of a contrast medium provide a visual of the stomach. X-rays can demonstrate the presence of gastric dilatation volvulus, an extremely dangerous condition in which the stomach becomes overstretched. Upper endoscopy also helps to visualize the stomach.

A sodium chloride load test is a non-imaging clinical study often found to be helpful. This test involves an infusion of sodium chloride solution. The test measures to see how much of the solution remains in the stomach as opposed to exiting the stomach. The remaining amounts of solution are considered abnormal past a certain threshold.

Performing biopsies can rule out or confirm malignancy. Biopsies may be CT-scan-guided and may involve fine-needle aspiration. If cancer is suspected, imaging tests will be utilized to detect the presence of metastatic cancer. In addition to CT scans, these could include magnetic resonance imaging (MRI)s.

Treatment & Therapy

Regardless of the cause of the gastric outlet obstruction, most patients benefit from electrolyte imbalance corrections and hydration. A regimen of proton-pump inhibitor therapy is one treatment approach for dealing with the problem if it is caused by duodenal ulcers. Proton-pump inhibitors reduce acid levels in the stomach, helping ulcers to heal and relieving symptoms.

If ulcers are unresponsive to medications, surgery may be considered. Antrectomy (removal of the antrum) and vagotomy (removal of vagus nerve) are two types of surgery. In the event that the case of gastric outlet obstruction is caused by cancer, surgery may be pursued depending on the type of cancer and what stage it is in.

Tumor resection is a type of surgery that can be used to excise the cancerous tumor completely. In patients with metastatic cancer, surgical intervention will be considered along with chemotherapy and radiation therapy.

Prevention & Prophylaxis