We don’t need the lab to tell us that the test may not be accurate. We all know that stool for occult blood can give both false positive and false negative results. But being doctors, we factor in that knowledge with the clinical situation.

I am proud to say that having recently passed the hospital’s inservice, I have been credentialed to perform fecal hemoccult tests without supervision. Hence, the lab is no longer in the loop.

I do agree, however, that many laboratory tests can have false positives and negatives, so why do they single this one out?

“I am a clinical lab scientist and had a rectal exam once, therefore I have conclusive knowledge about how doctors perform rectal exams.” Based on my extensive experience watching Dr. Edward Scissorhands and his progeny perform rectal exams, it is my opinion that patients are lucky they don’t need post-rectal exam abdominoperineal resections.

Rectal exams *could* cause bleeding. Labs want to *ensure* that clinicians get accurate results. Does your masters degree having wife possess any evidence that rectal exams *do* cause rectal bleeding more than bowel movements in her renowned hospital files? Any scientific evidence how these policies *ensure* proper clinical results? Studies maybe? Percentages of cases? Perhaps she has published a paper on the topic. Any scientific evidence at all, counselor? Do you think your wife would get past a Daubert hearing on the topic with her qualifications?
And why doesn’t your wife’s clinical laboratory publish disclaimers about all the conditions that may affect a laboratory sodium value? Or doesn’t your wife’s renowned hospital think that “ensuring” clinicians get accurate sodium results is important?

Come to think of it, I flew on an airplane once and I watch flight patterns on http://www.flightaware.com all the time. Perhaps I should contact the FAA to give them my opinions about air traffic control.

I’m glad that your wife and all of the clinical laboratory scientists think it is medically essential to verify the source of these samples before running them.

After all, for all we know the samples could be brain biopsies from the people who create these policies.

I sent her the post because I thought she’d find it interesting. This is what she says:

“Fingers can rip the anus making it bleed so then you don’t really know if the positive blood result is from that or an actual internal bleed. The disclaimer is necessary because lab staff doesn’t collect the sample and we do not know how they obtained it. There are special kits available to properly collect the sample. Docs never want to attend continuing ed sessions for POC lab testing but they always mess it up. If the lab had it our own way, we’d dicontinue all POC testing. All accurate test results begin with a quality sample.”

From my perspective, I have to call BS on WhiteCoat’s reply to Christine. Having had the experience of both a digital rectal exam and a bowel movement, anecdotally it isn’t hard to imagine that the DRE is way more likely to cause a tear than a big brown toilet trout is.

So it seems like the disclaimer is there to tell the physician “if you didn’t do the test right (and experience tells us you often don’t) the results may not be right, so don’t blame us.” This seems not litigation-driven, but designed to ensure that the clinician gets an accurate result, or if they know the sample was rectally collected, to tell them that they should be aware of the increased potential for a false positive.

Don’t get me wrong, I am sure there are instances where liability-driven disclaimers exist. This doesn’t look like one though. I think because WC has a hammer, the disclaimer looks like a nail to him.