Case: Consent and Capacity - Basic Case

A 20 year old female arrives in the emergency department 7 hours after the sudden onset of a severe headache. She describes it as the worst headache she has ever experienced. An initial CT scan of her brain does not show any evidence of sub-arachnoid hemorrhage but you think she should still have a lumbar puncture done to rule it out. She expresses concern about getting any more tests, and asks you to tell her more about the lumbar puncture. 

1) What are the elements of an informed consent?

2) What potential risks and benefits would you need to discuss with this patient?

3) How would you document this discussion?