How is Pulmonary Fibrosis Diagnosed?
A multiple step process is needed to diagnose pulmonary fibrosis. This process begins with an in-depth review of an individual's family history, current symptoms, as well as any environmental and occupational exposures that are associated with the development of pulmonary fibrosis.
Your Medical History
This includes a review of any symptoms suggestive of connective tissue diseases, a listing of all current and former medications, and a review of any environmental and occupational exposures to dusts, gases, chemicals, pets (in particular birds), air conditioners, and humidifiers.
Complete Physical Examination
A physical exam is often done to detect signs and symptoms of pulmonary fibrosis. Findings of crackling sounds in the lungs and changes in the skin, joints and fingernails can help direct further evaluation.
Testing and Procedures
Lung tissue showing pulmonary fibrosis
Testing or procedures that also help in diagnosis of pulmonary fibrosis may consist of the following:
A High Resolution Chest Computed Tomography (CT) Scan
A CT scan is like an X-ray, but it generates a 3D image of the inside of a person's body. After the CT scan has been performed, a radiologist evaluates the images generated. The results can help determine if pulmonary fibrosis is present.
Pulmonary Function Tests
Pulmonary function tests are tests performed to make measurements of how your lungs and airways function. These breathing test results are usually abnormal in pulmonary fibrosis.
Arterial Blood Gas
This test measures the amount of oxygen and carbon dioxide in your blood. The results may be normal or show a reduced oxygen level.
An exercise test requires a patient to exercise on a treadmill, bicycle, or other equipment. Measurements are taken to determine the response of the lungs to physical activity. In pulmonary fibrosis, this test may show a reduction in oxygen levels during exercise.
Bronchoscopy With Bronchoalveolar Lavage or Biopsy Bronchoscopy
A bronchoscopy allows the doctor to look inside the airways in the lungs. This test may be done to rule out other similar problems and to make sure infections are not present. Bronchoscopy involves inserting a tube through the nose into your trachea (windpipe) to see the airways. In bronchoalveolar lavage, a small amount of sterile saline is placed in one area of your lung and then withdrawn. This fluid contains cells that will be analyzed under the microscope. Small biopsy tools may be used through the bronchoscope if it is indicated.
Surgical Lung Biopsy
In many cases of pulmonary fibrosis, a surgical lung biopsy is needed to get enough lung tissue to make a specific diagnosis. This is often performed with the use of a thoracoscope passed through a small incision in the chest wall. This allows the surgeon to biopsy multiple areas of one lung through a few very small incisions. The method of obtaining a lung biopsy using a thoracoscope is called video assisted thoracoscopy or a “VATS” biopsy.
American Thoracic Society/ European Respiratory Society Guidelines
The American Thoracic Society/ European Respiratory Society published guidelines for the diagnosis of IPF.
Criteria for the Diagnosis of IPF in the absence of a surgical lung biopsy include the following:
The presence of all of the following major criteria:
- Exclusion of other known causes of ILD
- Abnormal pulmonary function studies that include evidence of restriction & reduced lung volumes
- Bibasilar abnormalities on High Resolution Computed Tomography
- Transbronchial lung biopsy or bronchoalveolar lavage that show no features of an alternative diagnosis
The presence of at least three of the following four minor criteria:
- Age older than 50 years
- Insidious onset of otherwise unexplained dyspnea on exertion
- Duration of illness greater than or equal to three months
- Bibasilar, inspiratory crackles (dry or "velcro"-type in quality)
Reference: Am J Respir Crit Care Med Vol 165. pp 277-304, 2002
This information has been approved by David Schwartz, MD (February 2010).