How Is Idiopathic Pulmonary Fibrosis Diagnosed?

Idiopathic pulmonary fibrosis (IPF) causes the same kind of scarring and symptoms as some other lung diseases. This makes it hard to diagnose.
Seeking medical help as soon as you have symptoms is important. If possible, seek care from a pulmonologist. This is a doctor who specializes in diagnosing and treating lung problems.
Your doctor will diagnose IPF based on your medical history, a physical exam, and test results. Tests can help rule out other causes of your symptoms and show how badly your lungs are damaged.

Medical History

Your doctor may ask about:

Your age
Your history of smoking
Things in the air at your job or elsewhere that could irritate your lungs
Your hobbies
Your history of legal and illegal drug use
Other medical conditions that you have
Your family's medical history
How long you've had symptoms

Diagnostic Tests

No single test can diagnose IPF. Your doctor may recommend several of the following tests.

Chest X Ray

A chest x ray is a painless test that creates a picture of the structures in your chest, such as your heart and lungs. This test can show shadows that suggest scar tissue. However, many people who have IPF have normal chest x rays at the time they're diagnosed.

High-Resolution Computed Tomography

A high-resolution computed tomography scan, or HRCT scan, is an x ray that provides sharper and more detailed pictures than a standard chest x ray.
HRCT can show scar tissue and how much lung damage you have. This test can help your doctor spot IPF at an early stage or rule it out. HRCT also can help your doctor decide how likely you are to respond to treatment.

Lung Function Tests

Your doctor may suggest a breathing test called spirometry (spi-ROM-eh-tree) to find out how much lung damage you have. This test measures how much air you can blow out of your lungs after taking a deep breath. Spirometry also measures how fast you can breathe the air out.
If you have a lot of lung scarring, you won't be able to breathe out a normal amount of air.

Pulse Oximetry

For this test, your doctor attaches a small sensor to your finger or ear. The sensor uses light to estimate how much oxygen is in your blood.

Arterial Blood Gas Test

For this test, your doctor takes a blood sample from an artery, usually in your wrist. The sample is sent to a laboratory, where its oxygen and carbon dioxide levels are measured.
This test is more accurate than pulse oximetry. The blood sample also can be tested to see whether an infection is causing your symptoms.

Skin Test for Tuberculosis

For this test, your doctor injects a substance under the top layer of skin on one of your arms. This substance reacts to tuberculosis (TB). If you have a positive reaction, a small hard lump will develop at the injection site 48 to 72 hours after the test. This test is done to rule out TB.

Exercise Testing

Exercise testing shows how well your lungs move oxygen and carbon dioxide in and out of your bloodstream when you're active. During this test, you walk or pedal on an exercise machine for a few minutes.
An EKG (electrocardiogram) checks your heart rate, a blood pressure cuff checks your blood pressure, and a pulse oximeter shows how much oxygen is in your blood.
Your doctor may place a catheter (a flexible tube) in an artery in one of your arms to draw blood samples. These samples will provide a more precise measure of the oxygen and carbon dioxide levels in your blood.
Your doctor also may ask you to breathe into a tube that measures oxygen and carbon dioxide levels in your blood.

Lung Biopsy

For a lung biopsy, your doctor will take samples of lung tissue from several places in your lungs. The samples are examined under a microscope. A lung biopsy is the best way for your doctor to diagnose IPF.
This procedure can help your doctor rule out other conditions, such as sarcoidosis (sar-koy-DO-sis), cancer, or infection. Lung biopsy also can show your doctor how far your disease has advanced.
Doctors use several procedures to get lung tissue samples.
Video-assisted thoracoscopy (thor-ah-KOS-ko-pee). This is the most common procedure used to get lung tissue samples. Your doctor inserts a small tube with an attached light and camera into your chest through small cuts between your ribs. The tube is called an endoscope.
The endoscope provides a video image of the lungs and allows your doctor to collect tissue samples. This procedure must be done in a hospital. You'll be given medicine to make you sleep during the procedure.
Bronchoscopy (bron-KOS-ko-pee). For a bronchoscopy, your doctor passes a thin, flexible tube through your nose or mouth, down your throat, and into your airways. At the tube's tip are a light and mini-camera. They allow your doctor to see your windpipe and airways.
Your doctor then inserts a forceps through the tube to collect tissue samples. You'll be given medicine to help you relax during the procedure.
Bronchoalveolar lavage (BRONG-ko-al-VE-o-lar lah-VAHZH). During bronchoscopy, your doctor may inject a small amount of salt water (saline) through the tube into your lungs. This fluid washes the lungs and helps bring up cells from the area around the air sacs. These cells are examined under a microscope.
Thoracotomy (thor-ah-KOT-o-me). For this procedure, your doctor removes a few small pieces of lung tissue through a cut in the chest wall between your ribs. Thoracotomy is done in a hospital. You'll be given medicine to make you sleep during the procedure.