Cytopathology
Even if blood is not visible in the airways, two types of cells that can be seen under cytological examination of either a tracheal wash or bronchoalveolar sample can indicate that EIPH has occurred. It may be possible to visualise red blood cells directly under a microscope. The number of red blood cells present can be quantified using a haemocytometer. While some red blood cells may be present in a lung wash sample, this is normally very low and in the order of less than 10 red blood cells/ul of fluid. In the case of EIPH, the numbers will be several magnitudes or more higher. The presence of high numbers of hemosiderophages also indicate that hemorrhage has occurred in the lung at some time in the past. Hemosiderophages are alveolar macrophages that have ingested and digested red blood cells from previous episodes of EIPH. The end product of the digestion of the red blood cells is an iron-storage complex known as hemosiderin.
Read more about this topic: Exercise Induced Pulmonary Hemorrhage, Diagnosis