Alveolar Hemorrhage

Diffuse alveolar hemorrhage (DAH) is a life-threatening condition, characterized by extensive intra-alveolar hemorrhage. This condition can result from a variety of diseases such as vasculitis, primary systemic as well as secondary pulmonary hypertension, autoimmune diseases including collagen vascular diseases, Goodpasture syndrome, antiphospholipid autoantibody syndrome, infections such as tuberculosis, influenza virus, hantavirus, SARS, dengue fever, Nile virus fever, inhalation of herbicides and pesticides, drug reactions, especially cytostatics. Most cases of DAH are caused by capillaritis associated with systemic autoimmune diseases. In BAL specimen, there are red blood cells as well as hemosiderin-laden macrophages—it is essential to differentiate DAH from artificial bleeding induced by bronchoscopy or biopsy, as well as from aspiration from the upper respiratory tract. DAH may also occur as an idiopathic condition. It should be distinguished from focal pulmonary hemorrhage secondary to infections, arteriovenous malformation or pulmonary embolism. Early bronchoscopy with bronchoalveolar lavage is usually the first approach to exclude infections. Biopsy can help to identify the cause to direct the therapy.