What tests will be used to diagnose the cause of chronic cough?

What tests will be used to diagnose the cause of chronic cough?

Diagnosing the cause of chronic cough can be difficult. This may be because many patients have more than one thing causing their cough. Therefore, many types of tests are used to diagnose the causes. The other symptoms will help determine which tests are needed.

For both adults and children, but especially for children, the answers to questions your healthcare provider asks will provide clues about the cause. They'll ask questions such as when the coughing started, what seems to trigger the cough, and questions about the nature of the cough (like is it a dry cough or does it produce mucus). The answers will suggest what kind of testing is needed.

Lab tests help determine if bacteria are present (a sign of an infection) and are causing the cough. The most common of these involve blood tests. Others might test mucus that you cough up.

Lung function tests are tests that tell your healthcare provider how well your lungs are working. They are also called pulmonary function tests. These measure your breathing patterns — from inhaling to exhaling. Spirometry is one type of lung function testing, while others are lung volume testing, gas diffusion studies and the six-minute walk test.

Imaging tests include X-rays, CT and MRI scans, ultrasound and nuclear testing. X-rays reveal the more common reasons for chronic cough, such as a build-up of fluids in the areas that help breathing, as well as lung diseases and lung cancer. All of the other imaging tests provide more detailed views of areas of the body that affect breathing.

Scoping studies are tests that use a scope. This is an instrument that combines a camera and a long tube. To find the reason for a chronic cough, a scope is passed into certain areas of the body that might reveal a problem. For example, a scope can be passed:

• Up through the nostrils to look for signs of infection or blockages in the nasal passages.
• Through the nose into the voice box area to look for signs of acid reflux, post-nasal drip and abnormalities in the upper airway.
• Down the esophagus and into the stomach to measure the level of acid, which would help determine if acid reflux is the cause of chronic cough.
• Down the windpipe and into the bronchial tubes to look for blockages and signs of infections in the lung.

In terms of diagnosis, there’s one last thing you might hear. Sometimes, the cause of chronic cough cannot be found, so the cough is said to be idiopathic. (This is the medical term used when a cause is unknown and stays that way.) The cough that can’t be stopped might also be called unexplained chronic cough or chronic refractory cough.