Sputum induction

What is a sputum induction test? 

A 'sputum induction' test is a simple test that involves producing a fresh sample of sputum to be analysed. 

Why do I need to have this test? 

The doctor has requested that you have this test to analyse your sputum for different cells found in your lungs. 

What happens during the test?

Before the test starts the Physiologist will explain the test to you in detail and will answer any questions that you may have. The sputum induction test is a painless procedure.

Preparing for the test

What should I do before the test?

Please inform the clinic coordinator (phone number on your appointment letter) if any of the following apply to you:

• You have coughed up any blood in the last 2 months. 
• You have been told you have a collapsed lung. 
• You have used your GTN spray in the last few months for chest pain. 
• You have been told you have a blood clot. 
• You have had a heart attack in the last 2 months. 
• You currently or have had recently had a chest infection requiring antibiotic treatment. 
• You have had any surgery in the last 2 months (including eye surgery). 
• If you feel unwell on the day of the test.

Please follow these important instructions:

• Do not smoke for 4 hours before the test. 
• Do not drink alcohol for 4 hours before the test.
• Do not do any vigorous exercise 30 minutes before the test.
• Do not eat a substantial meal 2 hours before the test. 
• Do not wear lipstick or nail varnish to the appointment.

What should I wear to my test?

You should wear normal comfortable clothing.

Will I experience any discomfort or side effects?

The saline used can cause narrowing in your airways. To prevent this you will be given a medication (salbutamol) to open up the airways at the start of the test. 

There are no long term side effects of performing the test. You may however find it tiring because of the repeated coughing, and it can irritate the throat. You will be given time to recover between tests.

After the test

What happens after the test?

If we are able to produce a sample, it will be sent for analysis.

When/how will I receive the results of the test?

You are usually told your results at your next clinic appointment or a letter may be sent to the healthcare professional who referred you for the test.

What happens if I don’t want the test?

It is your decision but if you do not attend, we will not be able to pass important diagnostic information to your clinical team. This may affect the medical treatment you receive.

Is there a different test I could have?

There are no other simple tests that provide the same information.

References

© North Bristol NHS Trust. This edition published July 2024. Review due July 2027. NBT002337.