Hemoptysis is the expectoration of blood, or the presence of blood in the sputum. Young children usually swallow their sputum; as a result, hemoptysis is rare in children unless the bleeding is substantial .
The term hemoptysis refers to expectoration of blood originating from the lower respiratory tract. Blood from the upper respiratory tract, nasopharynx, and upper gastrointestinal tract can be expectorated and can mimic true hemoptysis. (See 'Mimics of hemoptysis' below.)
There is no consensus for quantifying the degree of hemoptysis. In adults, a common threshold for defining massive hemoptysis is expectoration of ≥500 mL over a 24-hour period, or bleeding at a rate of ≥100 mL/hour. In patients with cystic fibrosis (CF), a consensus panel classified hemoptysis as follows :
●Scant – less than 5 mL
●Mild to moderate – 6 to 240 mL