Stool guaiac test

Hemoccultcommon testFaecal occult blood (FOB) testguaiacGuaiac cardsguaiac-basedguaiac-based fecal occult blood teststool guaiac
The stool guaiac test or guaiac fecal occult blood test (gFOBT) is one of several methods that detects the presence of fecal occult blood (blood invisible in the feces).wikipedia
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Fecal occult blood

fecal occult blood testoccult bleedingFecal Immunochemical Test
The stool guaiac test or guaiac fecal occult blood test (gFOBT) is one of several methods that detects the presence of fecal occult blood (blood invisible in the feces).
Other tests look for globin, DNA, or other blood factors including transferrin, while conventional stool guaiac tests look for heme.

Guaiacum

guaiacguayacánguayacan
The test involves placing a faecal sample on guaiac paper (containing a phenolic compound, alpha-guaiaconic acid, extracted from the wood resin of Guaiacum trees) and applying hydrogen peroxide which, in the presence of blood, yields a blue reaction product within seconds.
A phenolic compound derived from the resin of Guaiacum trees is used in a common test for blood in human stool samples.

Colorectal cancer

colon cancerbowel cancerintestinal cancer
Though the FIT test is preferred, even the guaiac FOB testing of average risk populations may have been sufficient to reduce the mortality associated with colon cancer by about 25%.
Fecal occult blood testing (FOBT) of the stool is typically recommended every two years and can be either guaiac-based or immunochemical.

Blood

human bloodhematologicaloxygen consumption
The stool guaiac test or guaiac fecal occult blood test (gFOBT) is one of several methods that detects the presence of fecal occult blood (blood invisible in the feces).

Feces

faecesdungexcrement
The stool guaiac test or guaiac fecal occult blood test (gFOBT) is one of several methods that detects the presence of fecal occult blood (blood invisible in the feces).

Resin

resinsresinouspine resin
The test involves placing a faecal sample on guaiac paper (containing a phenolic compound, alpha-guaiaconic acid, extracted from the wood resin of Guaiacum trees) and applying hydrogen peroxide which, in the presence of blood, yields a blue reaction product within seconds.

Hydrogen peroxide

H 2 O 2 H2O2HO
After applying the feces, one or two drops of hydrogen peroxide are then dripped on to the other side of the film, and it is observed for a rapid blue color change.

Quinone

quinonesquinoidAQDS
When the hydrogen peroxide is dripped on to the guaiac paper, it oxidizes the alpha-guaiaconic acid to a blue colored quinone.

Type I and type II errors

Type I errorfalse-positivefalse positive
The guaiac test can often be false-positive which is a positive test result when there is in fact no source of bleeding. Vitamin C can cause analytical false negatives due to its anti-oxidant properties inhibiting the color reaction.

Vitamin C

ascorbic acidascorbateC
Vitamin C can cause analytical false negatives due to its anti-oxidant properties inhibiting the color reaction.

Nonsteroidal anti-inflammatory drug

NSAIDNSAIDsnon-steroidal anti-inflammatory drug
The package insert guidelines from the manufacturers, for example Hemoccult SENSA, recommend that nonsteroidal anti-inflammatory drugs (NSAID), such as ibuprofen and aspirin, and iron supplements be discontinued for at least several days before the tests.

Hemorrhoid

hemorrhoidshaemorrhoidspiles
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Anal fissure

anal fissuresrectal fissureAnal bleeding
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Ulcerative colitis

colitis ulcerosaColitisinflammatory colitis
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Crohn's disease

Crohn’s diseaseCrohn diseaseCrohn
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Coeliac disease

celiac diseaseceliac spruecoeliac
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Gastroesophageal reflux disease

acid refluxgastroesophageal refluxGERD
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Esophagitis

erosive esophagitisOesophagitisreflux esophagitis
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Peptic ulcer disease

peptic ulcerstomach ulcerulcer
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Gastritis

Chronic gastritisacute gastritisstomach inflammation
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Inflammatory bowel disease

inflammatory bowel diseasesIBDindeterminate colitis
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Portal hypertensive gastropathy

However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Aortoenteric fistula

aorto-enteric fistulaeaortoenteric
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Haemobilia

hemobiliableeding from the common bile duct
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.

Endometriosis

Endomentriosisendometriosis,endometriotic
However, other possible positive results include: gastroesophageal cancer, GI bleeds, diverticulae, hemorrhoids, anal fissures, colon polyps, ulcerative colitis, Crohn's disease, celiac disease, GERD, esophagitis, peptic ulcers, gastritis, inflammatory bowel disease, vascular ectasias, portal hypertensive gastropathy, aortoenteric fistulas, hemobilia, endometriosis, and trauma.