Hemoptysis, or coughing up blood, can be a symptom of COVID-19. While common signs include fever, fatigue, and a persistent dry cough, bleeding from the lungs is a less common manifestation. This symptom is generally associated with more severe forms of the disease, reflecting the damage the SARS-CoV-2 virus inflicts on the respiratory system.
How Common is Hemoptysis in COVID-19?
The appearance of blood when coughing is not a typical presentation of COVID-19, with reported prevalence generally ranging between 0.9% and 5% of cases. Minor hemoptysis often presents as small streaks of blood mixed into mucus or sputum, usually resulting from a forceful cough irritating the respiratory passages.
Bleeding that is more than just streaked sputum signals a more serious underlying issue. Massive hemoptysis, the expectoration of a large volume of blood, is an uncommon but life-threatening complication of severe COVID-19 pneumonia. This severe bleeding is observed more often in critically ill patients or those with pre-existing lung conditions.
Data suggests a connection between hemoptysis and the development of blood clots within the lungs. The incidence of hemoptysis can rise to as high as 13% in COVID-19 patients who have developed a pulmonary embolism, which is a blockage in a lung artery. This symptom, while rare, can be a warning sign of a severe, potentially life-threatening complication.
Biological Mechanisms of Bleeding
The SARS-CoV-2 virus and the body’s reaction create a destructive environment in the lungs that can lead to bleeding. One primary mechanism involves endotheliitis, the direct injury the virus causes to the cells lining the blood vessels. By infecting and damaging these endothelial cells, the virus compromises the integrity of the pulmonary capillaries, causing blood to leak into the air sacs.
Severe inflammation, or pneumonitis, further contributes to this damage by causing diffuse alveolar damage. This widespread injury to the air sacs and surrounding tissue compromises the structural components of the lung. This results in alveolar hemorrhage, which is bleeding directly into the lung tissue, a hallmark feature of severe viral pneumonia.
Compounding the direct damage is the profound hypercoagulable state induced by COVID-19, characterized by elevated inflammatory markers and clotting factors. This state promotes the formation of microthrombi, or tiny blood clots, within the small vessels of the lungs (pulmonary microangiopathy). When these clots block blood flow and cause tissue death (infarction), the compromised tissue may bleed into the airways.
Another potential cause relates to the severe inflammatory response irritating the bronchial arteries. Inflammation can lead to necrotizing bronchitis, where the airways become eroded and bleed. Furthermore, extensive lung damage can predispose patients to secondary bacterial or fungal infections known to erode blood vessels and cause significant hemoptysis.
Recognizing Severity and Seeking Medical Attention
Any instance of coughing up blood warrants a medical evaluation, but the volume and nature of the blood determine the urgency of the response. If the expectorated blood is only a small amount, appearing as streaks in mucus, and the patient is stable without difficulty breathing, contact a healthcare provider for guidance. While minor bleeding may be due to forceful coughing and irritation, professional assessment is required to rule out serious causes.
Immediate emergency medical assistance is necessary if the amount of blood is significant. Massive hemoptysis is typically defined as the expectoration of more than 100 to 200 milliliters of blood within a day, but any amount causing respiratory distress or lightheadedness is an emergency. Bright red blood suggests recent, active bleeding, while dark, clotted blood may indicate older bleeding.
Beyond the volume of blood, other symptoms signal a medical emergency and require calling emergency services immediately. These signs include difficulty breathing, severe chest pain, feeling faint or dizzy, or a rapid drop in blood pressure. Hemoptysis in a patient with COVID-19 symptoms must be taken seriously, as it can indicate life-threatening conditions like a large pulmonary embolism or extensive pulmonary hemorrhage.