A&E doctors will assess it on the spot to determine how serious your case is.
bro GiantCanopy can advise better on this issue.
but from what i know from A&E, from 2 near-death experiences and one or two other not-so-serious issues.. here it is:
1) if you sprained your ankle at night, doctors won't see to you immediately. even a fever is considered nothing unless there's some other symptoms like diarrhoea or vomiting
2) i had a bad case of alcohol poisoning once after consuming more than 20 types of alcohol poisoning in 4 hours. doctor told my parents my heart almost stopped beating and i was immediately rushed in unconscious. those that just had a little cut or bad cough will have to wait.
3) i had a serious asthma attack whereby for 3 days i couldn't walk more than 10 steps without feeling breathless. finally my parents dragged me down to the A&E at TTSH and when i saw an old man who was queuing up for some arm injury, i questioned the doctor and nurse why couldn't they let him go first. and the doctor said this to me:
"your case is much more serious. if we don't attend to you straight away, you might just collapse. don't worry, we know who needs attention first"
now. a fever is just a fever. all of us tend to over-worry when our loved ones fall sick. but the question is, how sick is that person that you require urgent medical attention, that you would try to get them to the doctor first and bypass everyone else?
it's all right to be worried, but sometimes you need to ask yourself if you're just being overly worried.