Gastritis
Gastritis is inflammation of the stomach lining.
The stomach lining resists irritation and can usually withstand very strong acid. Nevertheless, in gastritis, the stomach lining becomes irritated and inflamed.
Causes
Gastritis can be caused by many factors, including infection, injury, and disorders of the immune system.
Gastritis may be caused by infections with bacteria, viruses, or fungi. Worldwide, the most common cause of gastritis is infection with Helicobacter pylori bacteria. Viral or fungal gastritis may develop in people with a prolonged illness or an impaired immune system, such as those with AIDS or cancer or those taking immunosuppressant drugs.
Erosive gastritis involves both inflammation and wearing away of the stomach lining. Erosive gastritis results from irritants such as drugs, especially aspirin and other NSAIDs; Crohn's disease; bacterial and viral infections; and the ingestion of corrosive substances. In some people, even a daily baby aspirin can injure the stomach lining. Erosive gastritis can develop suddenly but more commonly develops slowly, usually in people who are otherwise healthy.
Acute stress gastritis, actually a form of erosive gastritis, is caused by a sudden illness or injury. The injury may not even be to the stomach. For example, extensive skin burns and injuries involving major bleeding are typical causes. Exactly why serious illness can lead to gastritis is not known but may be related to decreased blood flow to the stomach or to impairment of the stomach lining's ability to protect and renew itself.
Radiation gastritis can occur if radiation is delivered to the lower left side of the chest or upper abdomen, where it can irritate the stomach lining.
Postgastrectomy gastritis occurs in people who have had part of their stomach surgically removed (a procedure called partial gastrectomy). The inflammation usually occurs where tissue has been sewn back together. Postgastrectomy gastritis is thought to result when surgery impairs blood flow to the stomach lining or exposes the stomach lining to an excessive amount of bile (the greenish yellow digestive fluid produced by the liver).
Atrophic gastritis occurs when antibodies (see Section 16, Chapter 183) attack the stomach lining, causing it to become very thin and to lose many or all of the cells that produce acid and enzymes. This condition usually affects older people, particularly those who are chronically infected with Helicobacter pylori bacteria. It also tends to occur in those who have had part of their stomach removed.
Eosinophilic gastritis may result from an allergic reaction to an infestation with roundworms. In other cases, the cause is unknown. In this type of gastritis, eosinophils (a type of white blood cell) accumulate in the stomach wall.
Ménétrier's disease, whose cause is unknown, is a type of gastritis in which the stomach wall develops thick, large folds; enlarged glands; and fluid-filled cysts. The disease may be due to an abnormal immune reaction and has also been associated with H. pylori infection.
In plasma cell gastritis, plasma cells (a type of white blood cell) accumulate in the stomach wall and other organs. Why this happens is not known.
 See the sidebar When the Stomach Is Infected.
Symptoms and Complications
Gastritis usually causes no symptoms. When symptoms do occur, they vary depending on the cause and may include pain or discomfort or nausea or vomiting, problems that are often simply referred to as indigestion. Gastritis can lead to ulcers, at which time the symptoms may get worse.
Nausea and intermittent vomiting can result from erosive gastritis, radiation gastritis, Ménétrier's disease, and plasma cell gastritis. Pain or discomfort (dyspepsia) can occur, especially with erosive gastritis, radiation gastritis, postgastrectomy gastritis, and atrophic gastritis. Very mild pain or discomfort also occurs with acute stress gastritis.
Ulcers can develop with several types of gastritis, especially acute stress gastritis, erosive gastritis, and radiation gastritis. Ulcers may bleed, causing a person to vomit blood (hematemesis) or pass tarry black stools (melena). Acute stress gastritis may lead to bleeding from ulcers within a few days after an illness or injury, whereas bleeding tends to develop more slowly in the case of erosive gastritis or radiation gastritis. Persistent bleeding can lead to symptoms of anemia, including fatigue, weakness, and light-headedness. If an ulcer perforates (pierces) the stomach wall, stomach contents may spill into the abdominal cavity, resulting in peritonitis (inflammation and usually infection of the lining of the abdominal cavity) and sudden worsening of pain.
Some complications of gastritis are slow to develop. The scarring and narrowing of the stomach outlet that can result from gastritis, especially from radiation gastritis and eosinophilic gastritis, can cause severe nausea and frequent vomiting. In Ménétrier's disease, fluid retention and swelling of the tissues (edema) may occur because of loss of protein from the inflamed stomach lining. About 10% of people with Ménétrier's disease develop stomach cancer some years later. Postgastrectomy gastritis and atrophic gastritis may cause symptoms of anemia, such as fatigue and weakness, because of decreased production of intrinsic factor (a protein that binds vitamin B12, allowing the B12 to be absorbed and used in the production of red blood cells). A small percentage of people with atrophic gastritis develop a condition called metaplasia, in which cells lining the stomach change and become precancerous. In an even smaller percentage of people, metaplasia leads to stomach cancer.
Diagnosis
A doctor suspects gastritis when a person has upper abdominal discomfort or pain or nausea. Tests usually are not needed. However, if the doctor is uncertain of the diagnosis, or if symptoms do not resolve with treatment, an examination of the stomach using an endoscope (a flexible viewing tube (see Section 9, Chapter 119)) may be needed. If necessary, the doctor can perform a biopsy (removal of a tissue sample for examination under a microscope) of the stomach lining.
Treatment
Regardless of the cause of gastritis, symptoms can be relieved with drugs that neutralize or reduce the production of stomach acid (see Section 9, Chapter 121). For mild symptoms, taking antacids, which neutralize acid that has already been produced and released in the stomach, is often sufficient. However, antacids have to be taken several times a day and often produce diarrhea or constipation. Drugs that reduce acid production include histamine-2 (H2) blockers and proton pump inhibitors. H2 blockers are usually more effective than antacids in relieving symptoms, and many people find them far more convenient. Proton pump inhibitors are prescribed when the strongest treatment is needed. When infection is a part of gastritis, antibiotics are also prescribed. Doctors may prescribe sucralfate, which helps to prevent irritation. When gastritis leads to ulceration that perforates the stomach wall, immediate surgery is usually needed.
People with erosive gastritis must avoid taking drugs, such as NSAIDs, that irritate the stomach lining. Some doctors prescribe proton pump inhibitors or misoprostol to help protect the stomach lining. However, the coxibs (COX-2 inhibitors such as celecoxib and rofecoxib) are less likely to irritate the stomach lining than the older NSAIDs.
Most people with acute stress gastritis recover fully when the underlying illness, injury, or bleeding is controlled. However, 2% of people in intensive care units have heavy bleeding from acute stress gastritis, which is often fatal. Therefore, doctors try to prevent acute stress gastritis after a major illness, major injury, or severe burn. Drugs that reduce acid production are commonly given after surgery and in most intensive care units to prevent acute stress gastritis. These drugs are also used to treat any ulcers that form. For people with heavy bleeding from acute stress gastritis, a wide variety of treatments have been used. Few of these treatments, however, improve the outcome. Blood transfusions may actually make bleeding worse. Bleeding points can be temporarily heat-sealed (cauterized) during an endoscopy, but bleeding often starts again if the underlying illness persists. If bleeding continues, the entire stomach may have to be removed as a lifesaving measure.
There is no cure for postgastrectomy gastritis or atrophic gastritis. People with anemia resulting from decreased absorption of vitamin B12 that occurs with atrophic gastritis must take supplemental injections of the vitamin for the rest of their lives.
Corticosteroids or surgery may be needed to relieve a blocked stomach outlet in eosinophilic gastritis. Removing part or all of the stomach may cure Ménétrier's disease. No drug treatment is effective.
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