This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following is the cause of secondary hemorrhage? 
Select and explain. 
A. Dislodgement of clot within 24 hours, B. Normalisation of blood pressure, C. Sloughing of blood vessel wall, D. All of the above
C: Sloughing of blood vessel wall
Answer: C: Sloughing of blood vessel wall 
Explanation: Primary hemorrhage is hemorrhage occurring immediately as a result of an injury (or surgery).
Reactionary hemorrhage is delayed hemorrhage (within 24 hours) and is usually caused by dislodgement of clot by resuscitation, normalisation of blood pressure and vasodilatation. Reactionary hemorrhage may also result from technical failure such as slippage of a ligature.
Secondary hemorrhage usually occurs 7-14 days after injury. It is caused by sloughing of blood vessel wall.