Performing a Guaiac Fecal Occult Blood Test (gFOBT) (Nursing)

00:01 Hey, guys, today I'm going to talk to you about performing a Guaiac Fecal Occult Blood Test.

00:08 I know that sounds complicated, but the word Guaiac is a part of the test, or reagent that lets us know if the test detects blood.

00:17 Fecal is referring to stools you may already know, and alcohol is referring to blood, hidden or not easily seen by the naked eye.

00:25 Therefore, we're discussing a test commonly used to detect hidden traces of blood in the stool. Now, depending on where in the world you practice, this type of point of care testing may or may not be in your policy.

00:38 It could be done in the lab by medical technicians.

00:41 But sometimes this test is done in the home setting or in a clinic setting, and this specific testing equipment is likely to look a little different depending on the setting and the region where you practice as well.

00:55 So it's important that you understand the reason for the test, what the specific parts of the test do, and that there's going to be some variations to equipment and the procedure being discussed.

01:06 So let's start with taking a look at the equipment you're going to need.

01:11 So we're taking a look at our equipment.

01:12 The first thing you're going to need is a guaiac test cord or the slides.

01:17 So it's going to look something like this.

01:19 You may also see the word hemoccult on the top.

01:23 That is actually what we're going to use for this test that we're discussing today.

01:27 You may also come across something that says gastrocult, which you might see as card looks really very similar, but make sure you read the name because that is not the test we're performing today.

01:39 You just want to make sure you keen on into the right test that you need.

01:43 We're also going to need some applicator sticks, clean gloves, of course the actual developer solution and a specimen container. Now, most of that's probably familiar to you, but it's the guaiac test cords and the developer solution that may look a little different depending on where you're at.

02:02 Now the guaiac card or the paper is special because it's impregnated with a chemical called a guaiac acid, which this can detect tiny amounts of blood that again you can't see with your eyes.

02:14 So let's talk about a little bit the neat part of how that works.

02:17 Now our blood contains a protein called hemoglobin.

02:20 You might have heard this already.

02:22 And hemoglobin acts like a tiny catalyst, which is something that helps a chemical reaction to occur. Now when this testing solution meets hemoglobin or our blood, it causes the guaiac paper to change color. So no blood means no color change.

02:40 But if there's blood present, you're going to actually see your hemoccult card turn blue. Now think about it, maybe as a more simple term like invisible ink. You can't see it until you add the special solution and then it reveals itself. Now this test is really useful because it can help us find blood in the stool that's too small to see with our eyes, which really could be an early warning sign that something needs to be checked out.

03:07 And it's really important to keep in mind this test is usually used as a preliminary test for additional, more complex testing later on.

03:16 Now, when you're collecting a fecal stool sample for testing, you need to consider the actual sample itself.

03:22 Now, if the sample is too small, maybe it's watery or mixed with urine.

03:26 It's not considered a good sample for testing.

03:30 So you want to think about this when collecting a sample, or really giving patient education or other directions on providing you a sample.

03:39 Now, if you've got the resources, some care facilities have a neat thing called a potty hat, as you see here to give the patients, which makes collection much easier.

03:48 You can place that potty hat towards the back of the toilet so the patient can urinate directly the toilet bowl and defecate into the potty hat, and it keeps them separate.

03:58 We've talked about a few considerations already when performing an occult test.

04:02 But we also want to consider what other factors could interfere with the test or the results. Now, usually your providers already kept this in mind when they order the test, but you should know in case it's a part of your organizational policy to review all this before running the test itself.

04:21 Now here's a really common factors medications.

04:25 All of these medications are potential interference with the test results.

04:29 Something as simple as aspirin or other NSAIDs like ibuprofen.

04:34 Your blood thinners for example like warfarin also a pretty common drug.

04:38 Don't forget about your supplements like vitamin C supplements can actually cause a false negative. And also iron supplements.

04:47 Now there's some other dietary restrictions also we need to consider.

04:51 All of these are believed that could result in a false positive test.

04:56 So if your patient eats a lot of red meat, raw or rare cooked meat, that could cause a false positive.

05:03 Or even some vegetables in large quantities.

05:06 Things like horseradish, turnips, broccoli, cantaloupe, lots of these vegetables, and again, large quantities could cause a false positive. Also, patients who are eating a large amount of foods containing vitamin C or again that supplement, as we've already discussed.

05:24 One key thing to think about is to ask your patient to try to refrain from these foods or medications. If it's safe for about 48 to 72 hours before the test, that's considered sufficient time to avoid the influence on the test.

05:38 So now let's go ahead and get started.

05:41 First, we want to go ahead and prepare our workspace by gathering all our necessary materials. We want to ensure we wash our hands and put on our gloves.

05:50 It's also going to be really helpful for this test to ensure proper lighting in a clean surface to perform the test.

06:00 Now, most guaiac cards have two windows and two sides.

06:04 We're going to apply a thin smear of stool specimen to the designated stool side using our applicator stick.

06:10 And then we're going to use the other end of the stick and apply a new sample from a different part of the sample to the second window of the test card without overloading the window, as this can lead false results.

06:22 So let me go ahead and do that now.

06:25 So wash our hands I'm donning my gloves.

06:31 And we're going to make sure we're using our hemoccult.

06:34 Because that is the test we're going to do.

06:36 This is our card that we're going to use.

06:40 I'm going to go ahead and open this up, take my stool specimen and we're going to smear it on form A, then I'm going to use the other end of my stick in a different part of the stool, and we're going to put it in the B window.

07:19 And I might need just a little bit more of the sample.

07:21 So I make sure I have an ample amount.

07:27 Without trying to overload my card.

07:30 So once I've obtained my sample, I'm going to go ahead and close the test card to and cover that immediately after I applied the specimen.

07:38 Now this protects the sample and prevents contamination.

07:41 And we want to make sure the cover is securely fastened.

07:44 And usually there's a tab at the bottom.

07:47 Now once we fasten this we're going to turn the card over and apply the two drops of developer solution on the back of the card for each test window.

07:57 Now most cards actually you wait about 30 to 60s and we're going to watch the test windows for color change within about 60s of applying the developer. Now what we should see is a blue color appearing within the time frame. If we do see that, that means we have a positive result for occult blood. And again, if there's no color change this means a negative result. So I'm going to take my developer.

08:24 Go ahead and take this off.

08:26 And as instructed we're going to put two drops on each side of the window. And do that. And I'm going to go ahead and close that.

08:38 So now we're going to open up our card and take a look at our results.

08:41 So I'm just going to flip this open.

08:44 And so when we look at our card here this is the type of blue result that we're going to look for. You see all around this side you've got that pretty significant blue on both sides. This is pretty typical of what you're going to see.

08:56 Now once we've obtained this result we're going to document the date, the time and the result in the patient's record.

09:03 We're going to dispose of all the testing materials in appropriate biohazard containers. We want to remove our gloves and perform our hand hygiene.

09:11 Now report any positive results to the health care provider immediately as this may indicate gastrointestinal bleeding, and that requires further investigation.

09:21 We also want to make sure we clean our workspace thoroughly with appropriate disinfectant and prepare for our next procedure.

09:29 Now, if you do wonder whether you got a false negative, consider whether the specimen was exposed to heat, light, or maybe excessive moisture, or if the developer solution is outdated. Now, a test card should never be reused, even if only one window was used initially.

09:46 If you do this test often, it can feel pretty routine to you as a health care provider. However, it can be scary experience for your patient and many patients. Avoid having this test done because they don't want to find out the results. A positive test can indicate something serious, like a gastrointestinal bleed or cancer, but both of those situations require multiple more tests, so stay professional and reassuring when performing this test. You are helping the health care team take care of someone during a vulnerable time.