This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Surgery
Reactionary haemorrhage occurs within: 
Select and explain. 
A. < 24 hours, B. 1-2 Days, C. 2 - 7 days, D. After 7 days
A: < 24 hours
Answer: A: < 24 hours 
Explanation: (< 24 hours): Ref: 60-LB (19-B & L 25th)Primary haemorrhage: - Occurs at the time of injury or operationReactionary haemorrhage: - may follow primary haemorrhage within 24 hours (usually 4-6 hours) and is mainly due to rolling (slipping) of a ligature, dislodgement of a clot or cessation of reflex vasospasmSecondary haemorrhage: - occurs after 7-14 days and is due to infection and sloughing of part of the wall of an artery.