ILD is diagnosed based on your signs and symptoms, as well as your medical history, occupational history, family history, and test results.
Your doctor may perform tests to diagnose ILD:
- Lung function tests: measure how much air you can breathe in and out, how fast you can breathe out, and how well your lungs deliver oxygen to the blood. The most common lung function test is called spirometry and measures how much air you can breathe out after taking a deep breath and how fast you can expel the air. Another test your doctor might perform is called oximetry. This test involves a small sensor device that is placed on your finger that measures how much oxygen is in your bloodstream.
- Imaging tests: X-ray or computed tomography (CT) scans are scans that provide images of the lungs. Doctors can visually inspect these images for signs of ILD. CT scans can be very useful in determining how much lung damage has been done by ILD, and can show patterns in the damage that can help with diagnosis. Your doctor may also take an echocardiogram, which is another type of imaging test that can show how well your heart is functioning and whether there is abnormal pressure on either side of the heart.
- Lung tissue analysis: your doctor may wish to examine a small amount of your lung tissue in a laboratory. This is called a biopsy. Your doctor may obtain the tissue sample using a bronchoscope, a small flexible tube that passes into your lungs through your nose or mouth and collects a very small tissue sample. Your doctor may also obtain a tissue sample in surgery, while you are under general anesthesia. It is possible to obtain a larger tissue sample surgically than when a bronchoscope is used.