Excerpt from Gastric Ulcer

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Background

Peptic ulcers are mucosal breaks of >3 mm and are common, occurring in about 10% of adults in Western countries (Levine, 2000). Gastric ulcers account for about one third of peptic ulcers, and duodenal ulcers account for the remainder (Levine, 2000). Because a small percentage ( <5%) of gastric ulcers are caused by ulcerated gastric carcinomas, all gastric ulcers must be carefully assessed to differentiate benign lesions from malignant lesions.

For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education article Peptic Ulcers.

Pathophysiology

Helicobacter pylori infection (Levine and Rubesin, 1995) and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) (Lanas et al, 1997; Lanza, 1997) are the 2 main factors in the pathogenesis of peptic ulcers. H pylori infection occurs in 75% of gastric ulcers and 90% of duodenal ulcers (Levine, 2000). Other possible factors include the use of steroids or aspirin, smoking, alcohol or coffee consumption, stress, delayed gastric emptying, and duodenogastric bile reflux.

Diseases and conditions that are associated with an increased risk of peptic ulceration include cirrhosis, chronic pulmonary disease, renal failure, and renal transplantation.

Frequency

United States

Approximately 15% of the US population has evidence of a peptic ulcer at some time (Levine, 2000). Of those ulcers, about 5% are gastric and the rest are duodenal. Overall, the incidence of gastric ulcers has been decreasing over the past 3-4 decades.

International

The frequency of gastric ulcers in other countries is variable and is determined primarily by the association of gastric ulcers with their major causes—namely, H pylori infection and NSAID use.

Mortality/Morbidity

The mortality rate for gastric ulcers has slightly decreased in the past few decades to approximately 1 case per 100,000 population (Levine, 2000). The hospitalization rate is approximately 30 cases per 100,000 population.

Sex

The prevalence has shifted from a male predominance to similar incidences in males and females.

Age

In contrast to the occurrence of duodenal ulcers in adults of all ages, gastric ulcers occur mainly in adults older than 40 years.

Anatomy

The stomach consists of the cardia (which is adjacent to the gastroesophageal junction), fundus, body, antrum, and pylorus. The fundus is dome shaped and extends above and to the left of the cardia toward the left hemidiaphragm. The body extends from the fundus to the lower end of the lesser curve, which is known as the incisura angularis. The antrum extends from the incisura to the pyloric canal.

The stomach is lined by peritoneum; the lesser omentum and greater omentum are double layers of peritoneum that extend from the lesser curve and greater curve, respectively.

Blood is supplied to the stomach by the right and left gastric, right and left gastroepiploic, and short gastric arteries, which originate from all 3 branches of the celiac trunk. The veins drain into the portal vein or 1 of its branches. The lymphatic vessels drain into the celiac lymph nodes surrounding the celiac trunk.

Clinical Details

The patient's history may include the following features:

• Typically, pain occurs less than 2 hours after meals, is localized in the epigastrium, and is gnawing, burning, or aching in nature. However, the pain may also be in the right upper abdominal quadrant, chest, or back.
• Anorexia, weight loss, belching, bloating, nausea, and/or heartburn may occur.
• Vomiting may be related to partial or complete gastric outlet obstruction.
• Hematemesis or melena may result from gastrointestinal (GI) bleeding.

Physical examination findings may include the following:

• In uncomplicated gastric ulcer, clinical findings are few and nonspecific.
• Epigastric tenderness may be present.
• Guaiac-positive stool may result from occult blood loss.
• Melena resulting from acute or subacute GI bleeding.
• A succussion splash resulting from partial or complete gastric outlet obstruction.

Complications of gastric ulcer disease include the following:

• Hemorrhage occurs in 20-30% of ulcers (Levine, 2000).
  • Endoscopy is the investigation of choice, with a sensitivity of more than 90% in the detection of the bleeding site.
  • Double-contrast barium studies are limited by poor mucosal coating in the presence of bleeding. Nevertheless, the bleeding site may be detected in as many as 75% of cases. A filling defect caused by a blood clot may be seen at the base of the barium-filled ulcer (see Images 1-2).
• Gastric outlet obstruction occurs in 5% of patients with peptic ulcers (Levine, 2000).
  • It is most common in duodenal ulcers, but it also occurs in antral or pyloric-channel ulcers.
  • The differential diagnosis includes malignant lesions, Crohn disease, and tuberculosis.
  • Nasogastric suction of the large gastric residue is required before performing the upper GI series.
    • The images typically show narrowing and deformity of the pylorus or duodenal cap.
• Perforation occurs in as many as 10% of patients with peptic ulcer disease but is less common in gastric ulcers (Levine, 2000).
  • Most perforations arise from ulcers in the anterior aspect of the duodenal cap and, less commonly, from the anterior aspect of the lesser curve of the stomach.
  • In 75% of cases, free gas is present in the peritoneum; this is best shown on an erect chest radiograph (see Image 3) rather than on an erect or supine abdominal radiograph (see Image 4).
  • An upper GI series performed with water-soluble contrast agent may demonstrate the presence and site of the perforation and whether it has sealed.
  • Subphrenic collections are common sequelae of a perforated peptic ulcer. They may be depicted on plain radiographs (see Image 5), but they are best assessed with ultrasonography or computed tomography (CT) scanning (see Image 6).
• Penetrating posterior-wall gastric and duodenal ulcers result in a walled-off perforation.
  • An abscess may form in the lesser sac.
  • The pancreas is involved in two thirds of cases.
  • A liver abscess may result from a penetrating ulcer in the lesser curve of the stomach.
• Gastroduodenal fistula, or a double-channel pylorus, is caused by a penetrating ulcer in the distal antrum that erodes directly into the base of the duodenal cap, or bulb. Twin channels communicate between the antrum and pylorus: the true pyloric canal and the fistula.
• Gastrocolic fistulas caused by carcinoma of the stomach or transverse colon have become less common than NSAID- or aspirin-induced ulcers in the greater curve. As these ulcers enlarge, they penetrate inferiorly into the gastrocolic ligament, later forming the gastrocolic fistula.

Preferred Examination

• Begin the evaluation with history taking and physical examination.
• Perform blood tests, including a full blood count and liver function tests.
• Inspect the stool, and test it for the presence of occult blood.
• Perform either fiberoptic endoscopy or a double-contrast barium study of the upper GI tract.
  • Endoscopy has become the diagnostic procedure of choice for patients with suspected duodenal ulcer. However, endoscopy is more invasive and costly than double-contrast barium study.
  • Double-contrast examinations of the upper GI tract remain a useful alternative to endoscopy but have a lower sensitivity, especially in the detection of small duodenal ulcers.
• Test for the presence of H pylori infection. This is essential in all patients with peptic ulcers.
  • Endoscopic or invasive tests include rapid urease, histopathologic, and culture tests.
    • Rapid urease tests are considered the endoscopic diagnostic test of choice. In gastric mucosal biopsy specimens, H pylori is detected by testing for the bacterial product urease. If H pylori is present, bacterial urease converts urea to ammonia, which changes the pH and produces a color change.
    • Histopathologic evaluation, often considered the criterion standard in the diagnosis of H pylori, requires a trained pathologist.
    • Cultures are used mainly in research studies.
  • Nonendoscopic or noninvasive tests include H pylori antibody detection and urea breath tests.
    • Levels of antibodies, such as immunoglobulin G (IgG), to H pylori can be measured in serum, plasma, or whole-blood samples. Whole-blood test samples are obtained with finger sticks, but the results are less reliable than those of other methods.
    • Urea breath tests are used to detect H pylori infection by testing for the enzymatic activity of bacterial urease. In the presence of urease produced by H pylori, carbon dioxide labeled with the heavy isotope, carbon-13 (¹³C), or the radioactive isotope, ¹⁴C, is produced in the stomach, absorbed into the bloodstream, diffused into the lungs, and exhaled.

Limitations of Techniques

Endoscopy has become the diagnostic procedure of choice in patients with suspected gastric ulcer. Biopsy samples obtained during endoscopy enable histologic diagnosis. Endoscopy with biopsy has a sensitivity of 95% (Levine, 2000). However, endoscopy is more invasive and costly than a double-contrast study, and multiple biopsy samples are needed to avoid sampling errors.

Single-contrast barium studies have an overall sensitivity of 75%, but double-contrast barium examinations have a sensitivity of as high as 95% in the detection of gastric cancer (Levine, 2000). These results are comparable to those of endoscopy, and double-contrast barium examination remains a useful alternative to endoscopy. Barium studies have a disadvantage in that biopsy specimens of the lesion cannot be obtained to test for H pylori infection or to evaluate for the presence of malignancy.

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