How Bronchitis Is Diagnosed

The diagnosis of acute or chronic bronchitis starts with a medical history and physical examination. A chest X-ray or chest CT scan can provide particularly helpful diagnostic information because these tests allow your doctor to visualize the appearance of your lungs. Blood tests and pulmonary functions tests may be helpful in determining whether you have bronchitis. These additional tests are most useful for ruling out other causes of your symptoms, including another lung disease, heart failure, or cancer.

Self-Checks/At-Home Testing

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© Verywell, 2018

Usually, there are signs that indicate that you or your child has more than just a regular cold. It is important to familiarize yourself with the symptoms of bronchitis because you are the first person who will notice that you might have the condition. You should get medical attention if you have signs of acute or chronic bronchitis. 

Acute and chronic bronchitis are both characterized by a productive cough, which is a cough accompanied by thick mucus. If you have acute or chronic bronchitis, your cough may also be exacerbated by environmental factors, such as smoke or other fumes. ​

Acute Bronchitis

In addition to the signs that are common to both acute and chronic bronchitis, there are indications that are specific to acute bronchitis. If you or your child has a cold in which a cough is the most prominent symptom, or if the cold seems to be lingering for longer than usual, then this may be acute bronchitis. 

Chronic Bronchitis

If you have a daily cough, lasting for at least three consecutive months for two years or more, then you may be dealing with chronic bronchitis. Pay attention to whether you also experience fatigue and if you develop shortness of breath with physical activity because these are also signs of chronic bronchitis. 

Labs and Tests

A number of labs and tests can support the diagnosis of bronchitis, although diagnostic tests alone are not enough to verify that you have bronchitis. These tests are used to determine the cause of bronchitis and to follow your progress if you have trouble breathing. 

Sputum Culture

A sputum culture is used to confirm the presence of bacteria in your sputum, which indicates that you have a respiratory tract infection.

If you have acute bronchitis, a positive sputum culture suggests that an infection is the cause of your symptoms. If you have chronic bronchitis, you are more prone to frequent lung infections, so you can have a positive sputum culture from time to time.

Complete Blood Count

A complete blood count, or CBC, is a routine blood test that provides your doctor with important information about the types and amounts of blood cells in your body. It can also help your doctor determine if you have an infection, which is more likely with acute bronchitis, but can occur with chronic bronchitis as well. 

Pulse Oximetry

A pulse oximeter is a small device that can estimate the oxygen saturation in your blood through your skin. This test can provide a reading within a few seconds, and it is done without any needles or injections. An abnormal oxygen level detected by a pulse oximetry reading suggests that you have a very advanced disease, while a normal reading cannot rule out bronchitis. 

Pulmonary Function Testing

Pulmonary function testing (PFT) uses spirometry to determine the presence and degree of airflow obstruction caused by chronic bronchitis. A spirometry test can be performed in your doctor's office, in the hospital, or in a healthcare clinic.

If you have acute bronchitis, you may have abnormal PFTs, but the test results should return to normal shortly after you recover from the infection. If you have chronic bronchitis, your PFTs could remain abnormal, or even worse without treatment. 

Arterial Blood Gas

Arterial blood gases (ABGs) are laboratory tests performed on blood taken from an artery. ABGs measure how well your lungs provide oxygen and remove carbon dioxide from your body.

Imaging

Imaging studies are particularly helpful in the evaluation of bronchitis because these studies can allow your doctor to see the changes that are happening in your lungs. Your doctor can also assess whether the changes are occurring in the lungs, the bronchi, or in other areas of your respiratory tract.

Chest X-Ray

A chest X-ray is not a definitive tool for diagnosing acute or chronic bronchitis, but your X-ray may show signs of inflammation of the bronchi, which can help confirm your diagnosis of acute or chronic bronchitis. A chest X-ray is also a tool for confirming lung infections like pneumoniaChronic obstructive pulmonary disease (COPD) includes a group of chronic pulmonary diseases such as chronic bronchitis. If you have symptoms of COPD, it is very likely that your doctor will get a chest X-ray to visualize your lungs. 

Chest CT

A chest CT gives a visual assessment of your lungs which can help identify bronchitis and can also rule out other conditions, such as lung infections, pulmonary embolus, or lung cancer. If you have symptoms of chronic bronchitis, there is a strong chance that your doctor will order a chest CT. 

Differential Diagnoses

There are several conditions that may produce symptoms similar to those of bronchitis. Your diagnostic tests and medical history can help differentiate between bronchitis and the other conditions. 

Pneumonia

Pneumonia is a lung infection, while bronchitis is inflammation of the bronchi. The bronchi are the airways that lead to the lungs. These illnesses both can cause wheezing and fatigue, but acute bronchitis causes a more severe cough than pneumonia, and chronic bronchitis does not typically produce a fever, whereas pneumonia does. When the symptoms are very similar, however, which they can be, a chest X-ray can help your doctor determine whether you have pneumonia or bronchitis. 

Asthma

Asthma can cause severe breathing difficulties and wheezing, which are usually more acute and severe than the breathing difficulties and wheezing of either acute or chronic bronchitis. However, because asthma recurs and chronic bronchitis symptoms recur, your doctors may need to differentiate these illnesses with a thorough medical history and chest imaging studies. 

Allergic Reaction

An allergic reaction can cause sudden episodes of shortness of breath. This is typically more dramatic than the shortness of breath that you may experience with bronchitis. However, because the treatment of the conditions is so different, your doctors may need to order allergy tests if your diagnosis is unclear. 

Emphysema

Emphysema is a condition in which the alveoli, which are the air sacs of the lungs, become affected by long-term pulmonary disease. You can have emphysema and chronic bronchitis, and they both are characterized by shortness of breath and fatigue. Your PFTs and imaging tests can help your doctors determine if you have one or both of these conditions. 

Heart Failure

As with chronic bronchitis, heart failure can cause you to have shortness of breath and fatigue with physical activity. There are differences that your doctor can detect on physical examination by listening to your heart and chest sounds with a stethoscope. It is not uncommon to have heart failure and chronic bronchitis at the same time, so your medical team will work to determine whether you have one or both of these conditions. 

Cancer

Cancer can produce a range of symptoms, including a cough, wheezing, and shortness of breath. If your symptoms are suggestive of cancer, your doctor is likely to order additional imaging tests and to consider a biopsy if there is an appearance of cancer on any of your imaging tests. 

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