Causes of Hemoptysis
There are many underlying disorders that can cause hemoptysis (coughing up blood), ranging from heart problems to trauma to infections to lung disease. Worldwide, tuberculosis is the most common cause of hemoptysis. In industrialized countries, the most common causes are bronchitis, bronchiectasis, and bronchogenic carcinoma.
In patients with AIDS, the most common cause of hemoptysis is pneumonia. In about 15% to 30% of cases, the underlying problem is never foundundiagnosed hemoptysis is commonly referred to as idiopathic hemoptysis.
Tuberculosis and Other Mycobacterial Infections
A mycobacterium is a type of bacteria that causes a variety of infections, including tuberculosis. A mycobacterial infection can destroy pulmonary tissue, usually by forming cavities in the airway walls.
The hemoptysis that results is usually mild to moderate and may be associated with other symptoms, including unexplained weight loss, cough, purulent sputum (thick, opaque, yellowish white discharge), and a history of mycobacterial exposure. A chest x-ray usually shows signs of infection, including a visible cavity, and the mycobacterium should be microscopically visible in the patient's sputum.
Bronchitis is an inflammation and swelling of the bronchi that can be acute or chronic. It is a very common cause of hemoptysis that results from recurrent coughing that irritates and eventually breaks down the mucosal lining of the airways.
The hemoptysis is usually mild and often associated with a purulent sputum (thick, opaque, yellowish-white discharge), low-grade fever and occasionally, wheezing. Usually the sputum is examined under the microscope to look for the pathogenic culprit. A chest x-ray is usually normal. The patient is usually prescribed cough suppressants and antibiotics.
Bronchiectasis is a chronic dilation and consequent infection of the bronchioles and bronchi that results from obstruction in the bronchi. The dilation results from damage to the surrounding supportive tissue and is usually a result of infection or fibrosis (the abnormal formation of scar tissue).
Cystic fibrosis is an example of a disease that leads to bronchiectasis. In addition to hemoptysis, patients with bronchiectasis often have a severe cough and chronic purulent sputum (thick, opaque, yellowish white discharge).
Bronchogenic carcinoma is cancer that originates in the lining of the bronchi. About 90% of lung cancers are bronchogenic. The other 10% begin in the bronchioles, alveoli, or trachea. Bronchogenic carcinoma is a less common cause of hemoptysis than bronchitis or bronchiectasis, but is an important one.
Most cases of bronchogenic carcinoma occur in smokers. If the disease is advanced, patients may experience unaccountable weight loss and various other common symptoms of lung cancer.
A chest x-ray can reveal the location of the neoplasm (tumor), and cancerous cells can often be detected in microscopic examination of the patient's sputum. The diagnosis sometimes cannot be confirmed until the tissue is biopsied.
About 7% of patients with bronchogenic cancer are initially diagnosed because of hemoptysis. About 20% of patients with bronchogenic cancer experience hemoptysis at some point. The bleeding results from necrosis of the tumor (death of the cells that make up the tumor), the rupture of small blood vessels in the area, or the tumor invading one of the pulmonary blood vessels. Massive bleeding can occur if the tumor erodes into one of the large pulmonary vessels.
Hemoptysis can also result from metastatic cancer to the lungs (especially breast, kidney, colon, and esophageal metastases). The cancer causes bleeding in much the same way that bronchogenic carcinoma causes bleeding.
Pneumonia is a lung infection caused by a number of different microorganisms. When a healthy person inhales one of these microbes, the immune system responds and prevents the microbe from reproducing and causing infection. But, in people with weakened immune systems (e.g., patients with AIDS), the microbes settle in the lungs, where they grow and multiply.
As the lung tissue tries to protect itself, the lungs fill with liquid and pus. In addition to hemoptysis, other symptoms include a high fever, cough, and chest pain.