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, preferably from a pulmonologist, as soon as you have symptoms is important. A pulmonologist 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 the results from tests. 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 your heart and lungs. It 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. It also can help your doctor decide how likely you are to respond to treatment.

Lung Function Tests

Your doctor will do a breathing test called spirometry (spi-ROM-eh-tre) to find out how much lung damage you have. A spirometer is a device that measures how much air you can blow out of your lungs after taking a deep breath. It also measures how fast you can breathe the air out.

If your lungs have a lot of scarring, you will not be able to move a normal amount of air out of them.

Pulse Oximetry

For this test, your doctor attaches a small device to your finger or earlobe. This device measures how much oxygen is in your bloodstream.

Arterial Blood Gas Test

For this test, your doctor takes a small amount of blood from an artery in your arm, usually in your wrist. The blood is then checked for oxygen and carbon dioxide levels.

This test is a more accurate way to check the level of oxygen in your bloodstream. Your blood also can be tested to see whether an infection is causing your symptoms.

Skin Test for Tuberculosis

For this test, your doctor injects a small amount of a substance that reacts to tuberculosis (TB) under the top layer of skin on one of your arms. 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 is done to find out 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) monitors your heart rate, a blood pressure cuff checks your blood pressure, and a pulse oximeter attached to a finger or ear lobe 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 samples of your blood. These samples will provide a more accurate measure of the oxygen and carbon dioxide in your blood.

Your doctor also may ask you to breathe into a tube that measures the amount of oxygen you've taken in and carbon dioxide you're breathing out.

Lung Biopsy

For a lung biopsy, your doctor will take samples of lung tissue from several places in your lungs and then examine them 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 causes of your condition, such as sarcoidosis, cancer, or infection. Lung biopsy also can show your doctor how far your condition has advanced.

Doctors use several different procedures to get lung tissue samples.

Video-assisted thoracoscopy (thor-ah-KOS-ko-pe). This is the most common procedure used to get lung tissue. Your doctor inserts a small, lighted tube with a camera (endoscope) into your chest through small incisions (cuts) between your ribs.

The endoscope provides a video image of the lungs and allows your doctor to collect samples of tissue. This procedure must be done in a hospital, and you'll be given medicine to temporarily put you to sleep.

Bronchoscopy (bron-KOS-ko-pee). For a bronchoscopy, your doctor passes a thin, flexible tube through your nose (or sometimes your mouth), down your throat, and into your airways. At the bronchoscope's tip are a light and a mini-camera, so your doctor can see your windpipe and airways.

Your doctor then inserts a forceps through the tube to collect tissue to examine. You'll be given medicine to make you relaxed and sleepy 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 for examination under a microscope.

Thoracotomy (thor-ah-KOT-o-me). For this procedure, your doctor removes a few small pieces of lung tissue through an incision in the chest wall between your ribs. Thoracotomy is done in a hospital, and you will be given medicine to temporarily put you to sleep.