LAST EDITED ON Jan-18-09 AT 01:15 AM (CST)
That is a significant discrepancy and it happens more often than you think. Paps are just a screening tool, and depending on the lab, a pretty bad one at that. Error margins range from 10% all the way up to 50%. At 50% you start to wonder if the pap is even worth it, especially if your insurance sucks. Common sense says inaccurate paps are always underread, not overread. It's a very superficial scraping.
The best liquid pap I've found is the SurePath. It takes the ENTIRE specimen to the lab without putting it through some centrifuge separator which removes some of the cells in the specimen. The more common liquid pap, ThinPrep (we've all heard of that one, right?) only ends up taking about 1/2 to 2/3 of your pap specimen to the lab. The part that's missing could contain dysplasia, so you'd never know bc it's not on the slide for the tech to read. The gyn I used when I first got hpv used SurePath but he is a complete moron so I stopped going to him, but the gyn I see now who is a bit better uses ThinPrep. She can't go outside of the practice's contract. Sigh.
Liquid paps are better than traditional dry cotton ball swabs (don't know what that's called, but my gyn-onc of all people still uses those!) but by no means perfect. My local lab reports a 10% error margin for liquid paps but I bet it's higher than that.
Finally, paps in the US are rarely reviewed by pathologists. ALL paps are first read by cytotechs. They have one year of training and are not MDs. (Not that being an MD necessarily means you are more knowledgeable or more competent.) I think only the abnormal ones are reread by paths. Paths in most labs perform a random reread of 10% of the normal paps.
But in any lab sample you are relying on a lot of different factors to go right in succession. That a good specimen was obtained, that it was not overprocessed or stored incorrectly or even lost (which once happened to three vials of blood that Quest took from me), that all or enough of the sample made it to the lab for an accurate reading, that the tech wasn't asleep at the wheel, that the reviewing path (if there was one) wasn't either, that the dictation was correctly reported (e.g. not truncated), it goes on!
Pathology, surprisingly, isn't an exact science and paths disagree all the time.
But I swear to god some paths don't know what the hell they are doing bc they recently misread my father's colon polyp as invasive cancer and the man was literally a day away from a colectomy when my brother got his mentors at a teaching institution to reread them and it turned out to be high grade dysplasia with some other feature resembling invasion but not invasion. My brother was soooo ticked. (Of course, we pray that the folks at the teaching institutions are right!)
And then the same lab in town misread my pityriasis rosea as friggin' FOLLICULITIS when the two look NOTHING alike under the microscope and I CLEARY had PR in the classic Langer lines pattern with herald patches and all which was 100% clinically evident. But I suppose my derm could have taken a bad specimen although it is very difficult to imagine having folliculitis on the smooth bare skin of my LOWER BACK.
Have I gone off good and loud now? Way more than you wanted to know, right? Guess I'll step off my soapbox and go to bed now.
Oops, I didn't even answer your question fully. It is rare but not impossible for high grade to develop within a year of nothing. Invasive cancer can develop in as little as 18 months given the right conditions (hpv 16/18 in the wrong body). And I went from a clean colpo and pap in May to lesions in three places including the canal in August of the same year. But more likely you had very mild cell changes that weren't detected. The idea is that a woman who is good about getting hear yearly paps won't progress to cancer even if the pap misses one or two early dysplasias bc it will eventually be picked up.
There is this new test in Europe called oncoFISH cervical that will render the pap obsolete. I'm excited. Some Italian clinics are already using it. Europe is so far ahead of the US with hpv stuff. Abnormal paps there are routinely tested for hpv STRAIN. And strain really matters! All high risk are NOT created equal.
CWC, I hope you will check back in to say you are hanging in there. Did you get the colpo or the HC II or both?