Queries :: Find Date In Table 1 Closest To Another Date In Table 2?

I have a table, tblVisits, holding patient's pre and post surgery visits:

Code:

PatientID VisitDate
1 1/5/12
1 3/10/12
1 9/1/13
2 ...

And another table holding patient's surgeries (each patient will have only one surgery)

Code:
PatientID SurgeryDate
1 4/1/12
2 ...

I need to compare these two tables and create a variable that indicates which pre-surgery visit date (i.e., VisitDate < SurgeryDate) is closest to the surgery date. In the above example, it would return:

Code:
PatientID VisitDate ClosestToSurgery
1 1/5/12
1 3/10/12 Yes
1 9/1/13
2 ...

I've tried various MIN and MAX approaches and can't seem to get it right.