Haemoptysis is the coughing of blood originating from the respiratory tract below the level of the larynx. Haemoptysis should be differentiated from:
- Haematemesis – vomiting of blood from the gastrointestinal (GI) tract.
- Pseudohaemoptysis – where a cough reflex is stimulated by blood not derived from the lungs or bronchial tubes. This may be from the oral cavity or nasopharynx (eg, following an epistaxis) or following aspiration of haematemesis into the lungs.
Classifications of severity vary. Although volumes of 100 to 1000 mL of blood have been described as indicative of massive haemoptysis, no specific volume has been universally accepted. However, a large volume of expectorated blood alone should not define massive haemoptysis, but rather an amount of blood sufficient to cause a condition that threatens the patient’s life is usually a more correct and functional definition of severe haemoptysis.
In most cases haemoptysis is a self-limiting event but in fewer than 5% it may be severe or massive, representing a life-threatening condition that warrants urgent investigations and treatment.
Despite haemoptysis being regarded as an ‘alarm’ symptom, no identifiable cause is found in 15-20% of cases and these are termed idiopathic or cryptogenic haemoptysis.
Haemoptysis is rare in children and often only presents where bleeding is substantial, as children tend to swallow rather than expectorate their sputum. Respiratory tract infection is the most common cause. Foreign body inhalation is the second most common cause (particularly with younger children) and congenital heart disease and bronchiectasis secondary to cystic fibrosis are other important causes.