bloody phlegm; bloody sputum
Medical and general term for phlegm or sputum containing blood. Often associated with respiratory conditions.
I had a persistent cough and coughed up bloody phlegm, so I went to the hospital.
Mixed kana-kanji spelling; may be used for readability or in less formal contexts.
Compound of 血 (blood) and 痰 (phlegm). The reading けったん is the standard on'yomi combination.