# Consumption to ensure a properly small Cologuard stool specimen **URL:** \ **Category:** Factual Questions\ **Created:** [March 4, 2022, 6:55pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474 "2022-03-04T18:55:23Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![PLGJ](https://avatars.discourse-cdn.com/v4/letter/p/439d5e/32.png) [@PLGJ](https://boards.straightdope.com/u/PLGJ)\ **Post date:** [March 4, 2022, 6:55pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/1 "2022-03-04T18:55:23Z")
Cologuard clearly say the bowel movement must be complete and still be only a small specimen. What and when to eat in order to manufacture such a bespoke turd? Cologuard states only that no preparation or special diet is necessary. Well that is nigh impossible for this big shitter. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [March 4, 2022, 10:24pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/2 "2022-03-04T22:24:45Z")
I don’t know Cologuard specifically, but every other stool sample container I’ve seen has a weird little spork as part of the vial’s cap so you can scoop out just a wee chunk. 💩 ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [March 5, 2022, 11:29pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/3 "2022-03-05T23:29:02Z")
Apparently it’s got to be no bigger than some bottle of liquid in the package. Sounds like a stinky procedure; first you have to take a small-ish dump in a little plastic canister, then scrape it with some sort of probe and put that in one container, then dump some sort of liquid in on the rest and seal that up really good and mail the whole shebang back to them. > **[Cologuard%20Patient%20Guide%20\_%20English.pdf](https://www.purdue.edu/hr/CHL/specialevents/pdf/Cologuard%20Patient%20Guide%20_%20English.pdf)** > > 3.84 MB ---
**Author:** ![Asuka](https://avatars.discourse-cdn.com/v4/letter/a/dec6dc/32.png) [@Asuka](https://boards.straightdope.com/u/Asuka)\ **Post date:** [March 6, 2022, 1:51am UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/4 "2022-03-06T01:51:48Z")
That reminds me of a time I had to take a urine test and they told me to drink A LOT of water beforehand to ensure a big sample since they’d be doing a lot of different tests, but apparently they got mad because I gave TOO MUCH and overfilled the 16 ounce tube. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 6, 2022, 2:50am UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/5 "2022-03-06T02:50:11Z")
> [@bump](#): > > Sounds like a stinky procedure; It is. For anyone doing this, I recommend a **[half-mask respirator](https://www.amazon.com/3M-Respirator-6300-Respiratory-Protection/dp/B007JZ1MK6)**, fitted with **[cartridges rated for organic vapor](https://www.amazon.com/3M-Cartridge-60923-Respiratory-Protection/dp/B00AEFCKKY)**. The alternative is to keep the lid on the container as much as possible, removing it only for the few seconds necessary to scrape it with the probe, but this offers pretty limited odor control. ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [March 6, 2022, 4:04pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/6 "2022-03-06T16:04:51Z")
If you think collecting one sample is bad, imagine the person(s) responsible for receiving and opening all those mailed-in samples. Thousands of them. Every day. Talk about one of the worst jobs in the world. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [March 6, 2022, 5:37pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/7 "2022-03-06T17:37:58Z")
> [@snowthx](#): > > imagine the person(s) responsible for receiving and opening all those mailed-in samples. As a corollary to Rule 34, I’m thinking there must be someone out there who would enjoy that job, maybe even too much. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 6, 2022, 6:58pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/8 "2022-03-06T18:58:34Z")
> [@snowthx](#): > > If you think collecting one sample is bad, imagine the person(s) responsible for receiving and opening all those mailed-in samples. Thousands of them. Every day. Talk about one of the worst jobs in the world. It’s almost certain that they’d be doing this work in a fume hood, so odor wouldn’t be any problem at all; you’d just have to deal with the visuals, and just as some folks aren’t squicked out by gore (surgeons and EMTs come to mind), some folks aren’t seriously nauseated by the mere sight of fecal matter. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 6, 2022, 8:51pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/9 "2022-03-06T20:51:06Z")
I mean, seriously, have you never changed a diaper? Yeah, it’s gross. Life’s like that sometimes. ---
**Author:** ![dauerbach1](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dauerbach1](https://boards.straightdope.com/u/dauerbach1)\ **Post date:** [March 8, 2022, 7:23pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/10 "2022-03-08T19:23:58Z")
I don’t know, but I suspect that Cologuard uses the tiny sample you provide by plunging the bristly thing into the sample and only opens the rest if they get a borderline or equivocal result. It is also not a particularly good test. If positive you have a 1.4% chance that it is a true positive. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [March 8, 2022, 7:36pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/11 "2022-03-08T19:36:10Z")
> [@snowthx](#): > > If you think collecting one sample is bad, imagine the person(s) responsible for receiving and opening all those mailed-in samples. I can only imagine the people doing that probably went into it with strong stomachs and quickly got over any other part of it that bothered them. Personally, I’d be puking. I gag a bit even thinking about having to do cologuard for myself someday. > [@Chronos](#): > > I mean, seriously, have you never changed a diaper? Not on an adult. > [@Machine\_Elf](#): > > some folks aren’t seriously nauseated by the mere sight of fecal matter. Me. It’s one of the driving reasons why I won’t get another dog. Every.single.time I have to pick up after them I’ll dry heave. > [@Machine\_Elf](#): > > (surgeons and EMTs come to mind) I’m sure, on average, they’ll have stronger stomachs for dealing with that, but not all of them. One of the guys on Night Watch (like Live PD, but EMTs and not live) was pretty well known for not being able to handle that smell. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 8, 2022, 7:52pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/12 "2022-03-08T19:52:15Z")
> [@dauerbach1](#): > > I don’t know, but I suspect that Cologuard uses the tiny sample you provide by plunging the bristly thing into the sample and only opens the rest if they get a borderline or equivocal result. It is also not a particularly good test. If positive you have a 1.4% chance that it is a true positive. The **[gold standard](https://en.wikipedia.org/wiki/Gold_standard_(test))** for colon cancer screening is the colonoscopy. Since colon cancer develops so slowly, once you have a colonoscopy, you can wait ten years for your next one. **[Cologuard definitely isn’t as good](https://www.cologuardhcp.com/about/clinical-offer)**: - Sensitivity is 92%, meaning that if you actually have colon cancer, there’s an 8% chance you’ll get a falsely negative result. - Specificity is 87%, meaning that if you actually don’t have colon cancer, there’s a 13% chance you’ll get a falsely positive result. False positives are bad because you get subjected to additional tests that you don’t actually need. In this case, the next step would probably be a colonoscopy. But if the alternative to Cologuard was to do the colonoscopy in the first place, then the only downside of this sequence of events is that you pooped in a cup when you didn’t need to. False negatives are bad because you miss out on treatment that you need. However, Cologuard is recommended every three years (not every ten like a colonoscopy). If you got a false negative today, then three years from now when your colon cancer has advanced a bit, you’d likely get a true positive - but since colon cancer moves slowly, you probably wouldn’t yet be in dire straits. For people who find colonoscopies unpleasant, Cologuard provides a much less unpleasant alternative that may be worth the risk of a false negative. For people who are so turned off by the idea of a colonoscopy that they avoid ever getting one at all, Cologuard is a life-saving development. ---
**Author:** ![dauerbach1](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dauerbach1](https://boards.straightdope.com/u/dauerbach1)\ **Post date:** [March 8, 2022, 8:30pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/13 "2022-03-08T20:30:54Z")
I was looking at things from the patients point of view. The PPV of the test is 1.4%. If your test is positive, this is the chance it is a true positive. This factors in the false positives which hugely outweigh the true positives. Specificity is for the epidemiologists in the crowd, not the individual patients. ---
**Author:** ![dauerbach1](https://avatars.discourse-cdn.com/v4/letter/d/67e7ee/32.png) [@dauerbach1](https://boards.straightdope.com/u/dauerbach1)\ **Post date:** [March 8, 2022, 8:34pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/14 "2022-03-08T20:34:51Z")
Also, the negative predictive value is 99.5%. This means with a negative result you have 1 chance in 200 of actually having cancer. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 8, 2022, 11:04pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/15 "2022-03-08T23:04:33Z")
> [@Machine\_Elf](#): > > If you got a false negative today, then three years from now when your colon cancer has advanced a bit, you’d likely get a true positive - but since colon cancer moves slowly, you probably wouldn’t yet be in dire straits. That depends on what kind of error causes the false negatives. Is it random, or systematic? I can envision situations that would lead to every instance of the test being independent, but I can also envision situations where a given patient would always test negative due to some quirk of the patient. Or more likely, of course, a mixture of both. ---
**Author:** ![PLGJ](https://avatars.discourse-cdn.com/v4/letter/p/439d5e/32.png) [@PLGJ](https://boards.straightdope.com/u/PLGJ)\ **Post date:** [March 23, 2022, 6:32pm UTC](https://boards.straightdope.com/t/consumption-to-ensure-a-properly-small-cologuard-stool-specimen/960474/16 "2022-03-23T18:32:46Z")
Thank you guise, all.