A gastric culture is a test to examine a child's stomach contents for the bacteria that causes tuberculosis.

This gastric culture can help diagnose lung (pulmonary) tuberculosis in children. This method is used because children cannot cough up and spit out mucus until about age 8. They swallow the mucus, instead. (That is why young children only rarely spread tuberculosis to others.)

The test may also be done to help identify viruses, fungi, and bacteria in the gastric contents of patients with cancer, AIDS, or other conditions that cause a weakened immune system.

A flexible tube is placed through the child's nose and into the stomach. The child may be given a glass of water and asked to swallow while the tube is inserted. Once the tube is in the stomach, the health care provider will remove a sample of the stomach contents using a syringe.

The tube is removed through the nose. The sample is sent to a laboratory, where it is placed in a special dish and watched for the growth of bacteria.

Your child will need to fast (no food or drink, including water) for 8 to 10 hours before the test.

The sample is collected in the morning. Performing the test too soon after the tube is placed can affect the results. For this reason, your child will likely be admitted to the hospital for the night. The tube can then be placed in the evening, and the test done first thing in the morning.

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• School age test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

While the tube is being passed through the nose and throat, your child will feel some discomfort and may also feel the urge to vomit.