Bronchoalveolar Lavage (BAL)
If blood is not visible in the trachea, then examination of the smaller airways in the lung may reveal hemorrhage. In this procedure sedation is commonly used and the endoscope is advanced past the carina into the smaller bronchi. Local anaesthetic is usually instilled into the airways to reduce coughing. BAL is performed and if a horse has experienced EIPH then the fluid that is recovered can be observed to be pink or red in colour. This fluid can be submitted for cytopathogy and the number of red blood counted. Whereas scoring of the amount of blood during endoscopic examination of the trachea is semi-quantitative, quantitative counts of the numbers of red blood cells in BAL represent a quantitative estimate of the severity of EIPH. BAL red blood cell counts are more sensitive for detecting EIPH than visualisation of blood in the trachea, but may be less useful in the case of severe hemorrhage.
Read more about this topic: Exercise Induced Pulmonary Hemorrhage, Diagnosis