According to UpToDate, to diagnose an acute herpes infection, viral culture on an unroofed lesion is only about 50% sensitive in diagnosing HSV. A much better (and expensive) test is to order the
of the mucosal specimen. The HSV PCR is especially helpful in detecting asymptomatic HSV shedding.
So where does serology fit in? To be honest, I'm not sure. I don't check HSC IgG since I don't typically care about testing for an previous infection (which may not reoccur). Testing for HSV IgM may be helpful, but in the setting of a very early initial or reactivated infection, it may be falsely negative.