Occurs after<unk> es in 3.9% of adults and 1.6% of children
Most common on POD 5-7
Highest incidence in 21-30 year olds
Lowest in <6 year olds
Post-tonsillectomy hemorrhage
Post-op pain
Carotid-cavernous fistula
Streptococcal pharyngitis 
Nasal septal hematoma
Neisseria gonorrhoeae
Vertebral and carotid artery dissection
Diphtheria 