One of the very common occurrences in the Emergency Department are falls and of course the majority of those who fall are elderly and on a blood thinner or some combination of blood thinners. 

I chose this paper because I wanted to know how common it is for patients in these circumstances to have an initially negative CT head and go on to develop a delayed intracranial hemorrhage.

Repeat head CT is unnecessary- incidence of delayed intracranial hemorrhage is very low and when it occurs it is clinically irrelevant. It may, however, be worthwhile to consider a repeat scan in those with a severe mechanism of injury (which is admittedly subjective) or obvious head trauma. 

In conclusion, a period of observation is reasonable but repeat head CT is costly and an unnecessary exposure to radiation.