noun
bloody phlegm; bloody sputum
Medical and general term for phlegm or sputum containing blood. Often associated with respiratory conditions.
咳が続いて血痰が出たので、病院に行った。
I had a persistent cough and coughed up bloody phlegm, so I went to the hospital.
喀血 refers specifically to coughing up blood from the respiratory tract, often in larger amounts, while 血痰 is blood mixed with phlegm.
Compound of 血 (blood) and 痰 (phlegm). The reading けったん is the standard on'yomi combination.