Hey,
I'm passing through OBGYN right now, so here's the most accurate answer I can give you. Most of it is based on Blueprints and lectures, though some of it comes from the (mostly incomprehensible and very management-oriented) lectures they give residents (which we're forced to attend, if the attending's particularly OCPD):
1- ASCUS: as the name implies, no one actually knows the significance of these. Basically, you have three options after finding ASCUS on a pap smear. You can:
a- repeat the pap smear in 6 months and, if you still aren't satisfied with the results, go for colposcopy and directed biopsy. If it's normal, go back to annual paps.
b- go for a colposcopy and directed bx from the start.
c- HPV-type the lesion. If it's positive for high-risk HPV, go for colpo. If not, ignore the ASCUS and go back to annual screening.
Which one to pick? Depends on the doc, really. They haven't come up with just ONE recommendation, which kinda sucks for us.
2- If you find ASC-H (atypical squamous cells-cannot rule out high grade lesion), LSIL (low-grade squamous intraepithelial lesion), or HSIL, go for a colposcopy and directed biopsy immediately.
3- If you find AGC (atypical glandular cells), well...these could either come from the endocervix (ie, this could be cervical ADENOcarcinoma) or from the endometrium. which is a pickle. you need to go for a colpo-directed biopsy and endocervical sampling, and/or--if she's >35 or has any risk factors for endometrial hyperplasia (granulosa-theca tumors, let's say)-- you need to take an endometrial biopsy.
[just one thing, the management of women < 20 is different. lesions there usually go away; not sure about the specifics, though.]
most low grade lesions (and ASCUS) tend to regress. things like HSIL tend to develop into carcinoma.
management of abnormal colpo-bx is pretty straightforward:
CIN-1: these usually regress (i think the regression rate is around 60%-ish). go for pap smears/HPV testing every 6 months for a year. If it's all good, you can go back to annual pap smears. If you get ASCUS or anything ugly again, do another bx. CIN-1 lesions that persist for at least 2 years should be excised with a cone biopsy.
CIN-2 and CIN-3 on colpo-directed bx: go for a cone biopsy (cuz these usually advance)...which is usually curative. you're supposed to f/u with pap smears, but i forget the details.
i DO hope this helps!