I'm willing to bet that the hospital didn't even provide that information. Drug tests are not a "magical black box", there's a process that goes on. And they a

I'm willing to bet that the hospital didn't even provide that information. Drug tests are not a "magical black box", there's a process that goes on. And they aren't always right. They usually first start off with immunoassay test on the urine which attempts to measure substances in urine through the use of antibodies. These are "okay" tests -- not bad per se, but they are definitely subject to a wide variety of false positives (http://jat.oxfordjournals.org/content/38/7/387.full http://jat.oxfordjournals.org/content/38/7/387.full). The reported false positive rate I can Google is all over the map, but I've seen articles suggesting as high as 10% (http://www.webmd.com/news/20100528/drug-tests-often-trigger-false-positives http://www.webmd.com/news/20100528/drug-tests-often-trigger-...). Drug testing uses these first because they are quick and relatively cheap. The gold standard, however, is GCMS testing. Very accurate, but expensive and time consuming. I assume that's the test performed in the article that took three weeks to resolve the false positive to the negative. Assuming the story as reported is true, I'm a little bit peeved that there was a de facto assumption by the nurses that the test was correct. The meth / amphetamine test in particular seems to be one of the more problematic immunoassays in the literature in that it false-positives with all sorts of prescriptions, along with some non-prescription drugs (http://www.medscape.com/viewarticle/726897_2 http://www.medscape.com/viewarticle/726897_2). 90% correct is not correct enough in my opinion when it comes to messing with people's children by threatening CPS.