Rapid urease test

Rapid Urease Test (RUT) is a diagnostic procedure used to detect the presence of Helicobacter pylori (H. pylori) bacteria, which is known to cause gastritis, peptic ulcer disease, and is associated with the development of gastric cancer. The test is based on the ability of H. pylori to produce the enzyme urease, which hydrolyzes urea to produce ammonia and carbon dioxide. The rapid urease test is commonly performed during gastroscopy or endoscopy, where a biopsy of the gastric mucosa is obtained and then exposed to a urea-containing medium. If H. pylori is present, the urease produced by the bacteria will rapidly increase the pH of the medium, leading to a color change that can be observed visually.

Procedure

The procedure for the rapid urease test involves several steps:

1. During an endoscopic examination, a small tissue sample (biopsy) is taken from the gastric mucosa.
2. The biopsy is then placed into a solution or gel containing urea and a pH-sensitive indicator.
3. The sample is incubated at room temperature.
4. Observation of the color change in the medium is made, usually within 24 hours. A positive test, indicating the presence of H. pylori, results in a rapid color change (often from yellow to pink or red) due to the alkaline ammonia produced by the action of urease.

Interpretation

A positive rapid urease test indicates the presence of H. pylori infection in the gastric mucosa. However, a negative test does not completely rule out the infection, as factors such as recent antibiotic or proton pump inhibitor (PPI) therapy can affect the test's accuracy. Further testing, such as urea breath test, stool antigen test, or serology, may be required for a definitive diagnosis.

Advantages and Disadvantages

The rapid urease test is favored for its simplicity, rapid results, and cost-effectiveness. However, its accuracy can be influenced by various factors, including the site of biopsy (with the antrum being the preferred site due to higher bacterial load), recent use of antibiotics, bismuth compounds, or PPIs, which can lead to false-negative results. Additionally, the test does not provide information on antibiotic susceptibility, which is crucial for treatment planning.

Clinical Significance

The detection of H. pylori infection is crucial for the management and treatment of associated diseases, such as peptic ulcers and gastritis. Eradication of the bacteria can lead to the healing of peptic ulcers and reduce the risk of gastric cancer development. The rapid urease test provides a quick and efficient method for diagnosing H. pylori infection, facilitating timely treatment decisions.

See Also

• Helicobacter pylori
• Gastroscopy
• Peptic ulcer disease
• Gastric cancer
• Urea breath test
• Stool antigen test
• Serology