Fecal occult blood is a term for blood present in the feces that is not visibly apparent. In medicine, a fecal occult blood test is a check for hidden (occult) blood in the stool (feces). Conventional fecal occult blood tests look for heme. Newer, modern tests look for globin. The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... // K00-K93 - Diseases of the digestive system (K00-K14) Diseases of oral cavity, salivary glands and jaws (K00) Disorders of tooth development and eruption (K01) Embedded and impacted teeth (K02) Dental caries (K03) Other diseases of hard tissues of teeth (K04) Diseases of pulp and periapical tissues (K040) Pulpitis (K05... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ... Medicine is the branch of health science and the sector of public life concerned with maintaining or restoring human health through the study, diagnosis, treatment and possible prevention of disease and injury. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ... Structure of Heme b A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... A globular protein is a protein that is globe-like, or rounded in shape, often soluble in aqueous solution. ...

Uses

Fecal occult blood testing - as its name implies - can provide clues as to subtle blood loss in the gastrointestinal tract, anywhere from the mouth to the colon. Positive tests ("positive stool") warrant further investigation for peptic ulcers or a malignancy (such as colorectal cancer or gastric cancer). The gastrointestinal tract or digestive tract, also referred to as the GI tract or the alimentary canal, (nourishment canal) or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and expels the remaining waste. ... Look up Mouth in Wiktionary, the free dictionary. ... In anatomy of the digestive system, the colon, also called the large intestine or large bowel, is the part of the intestine from the cecum (caecum in British English) to the rectum. ... Peptic ulcer is usually a non-malignant ulcer of the stomach (called gastric ulcer) or duodenum (called duodenal ulcer). ... When normal cells are damaged or old they undergo apoptosis; cancer cells, however, avoid apoptosis. ... Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. ... In medicine, stomach cancer (also called gastric cancer) can develop in any part of the stomach and may spread throughout the stomach and to other organs. ...

In the event of a positive fecal occult blood test, the next step in the workup is a form of visualization of the gastrointestinal tract (ie: endoscopy, colonoscopy, virtual colonoscopy). Endoscopic images of a duodenal ulcer Endoscopy means looking inside and refers to looking inside the human body for medical reasons. ... Colonoscopy is the minimally invasive endoscopic examination of the large colon and the distal part of the small bowel with a fiber optic camera on a flexible tube passed through the anus. ... Virtual colonoscopy (VC) is a Medical imaging procedure which uses x-rays and computers to produce two- and three-dimensional images of the colon (large intestine) from the lowest part, the rectum, all the way to the lower end of the small intestine and display them on a screen. ...

Annual testing of a population may reduce the mortality associated with colon cancer by a third, depending on the incidence of gastrointestinal cancer in that population. It is not always cost effective to screen a large population. Screening, in medicine, is a strategy used to identify disease in an unsuspecting population. ...

If colon cancer is suspected in an individual (such as in someone with an unexplained anaemia) fecal occult blood tests are usually not warranted. If a doctor suspects colon cancer, more rigorous investigation is necessary, whether or not the test is positive. This article discusses the medical condition. ...

Methodology

There are three methods for measuring heme in feces: Structure of Heme b A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ...

• Guaiac-based test (Hemoccult® or Instaccult®)
• Fecal porphyrin quantification (Hemoquant®) - high false positive rate.
• Immunochemical fecal occult blood tests (HemeSelect®) - more specific.
• Fecal DNA test (PreGen-Plus®) reportedly Four-Times More Sensitive Than Fecal Occult Blood Test for Colorectal Cancer Screening

from New England Journal of Medicine A porphyrin is a heterocyclic macrocycle made from 3 pyrrole subunits and one pyrroline subunit, and linked on opposite sides through 4 methine bridges. ... Scientists recognize two different sorts of error:[1] Statistical error: the difference between a computed, estimated, or measured value and the true, specified, or theoretically correct value that is caused by random, and inherently unpredictable fluctuations in the measurement apparatus. ...

One method: the test involves smearing some feces onto some absorbent paper that has been treated with a chemical. Hydrogen peroxide is dropped onto the paper; if trace amounts of blood are present, the paper will change color. This method works as hemoglobin has a peroxidase-like effect, rapidly breaking down hydrogen peroxide. Hydrogen peroxide (H2O2) is a very pale blue liquid which appears clear in a dilute solution, slightly more viscous than water. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... 3-dimensional structure of hemoglobin. ... Glutathione Peroxidase 1 A peroxidase (eg. ...

Since 2001, there are a new class of occult blood tests called Fecal Immunochemical Tests.

These tests detect the globin in feces rather than heme. By detecting globin the tests are both more sensitive and specific for lower gastrointestinal bleeding. A globular protein is a protein that is globe-like, or rounded in shape, often soluble in aqueous solution. ... Feces, faeces, or fæces (see spelling differences) is waste product from an animals digestive tract expelled through the anus (or cloaca) during defecation. ... Structure of Heme b A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... A globular protein is a protein that is globe-like, or rounded in shape, often soluble in aqueous solution. ... Lower gastrointestinal bleeding refers to any form of bleeding in the Lower gastrointestinal tract. ...

One test, called Insure, is designed to address patient ease of use by using a brush, not a wooden stick, to sample stools while in the toilet bowl. Using these tests there is no direct fecal handling and there is no need for changing diet or medication to perform the test. Finally the newer tests are more sensitive and so require only two samples rather than the traditional three day's testing.

Interpretation

The test is often false-positive (i.e. there is no source of bleeding). This is often due to recent ingestion of under-cooked meats, and a patient is generally advised to keep a meat-free diet for several days before handing in the feces sample. Scientists recognize two different sorts of error:[1] Statistical error: the difference between a computed, estimated, or measured value and the true, specified, or theoretically correct value that is caused by random, and inherently unpredictable fluctuations in the measurement apparatus. ... Vegetarianism is the practice of not consuming meat, with or without the use of other animal derivatives, such as dairy products or eggs. ...

False negatives may result if the patient has been taking vitamin C supplements. Scientists recognize two different sorts of error:[1] Statistical error: the difference between a computed, estimated, or measured value and the true, specified, or theoretically correct value that is caused by random, and inherently unpredictable fluctuations in the measurement apparatus. ... 3D representation of vitamin C Chemical structure of vitamin C Vitamin C is a water-soluble nutrient and human vitamin essential for life and for maintaining optimal health, used by the body for many purposes. ...

The test is more sensitive if the sample is hydrated before testing. However, the specificity is decreased in this method.

Newer, more sophisticated assays called Fecal Immunochemical Tests have been developed to address most of the deficiencies of traditional guaiac based fecal occult blood tests.

The stool-based DNA test, PreGen-Plus® was capable of detecting several stages of colorectal cancer, in otherwise healthy adults, and most importantly in its' early stage, the easiest and most effective to treat, stage of colorectal cancer.

Results

The DNA based PreGen-Plus®'s results were reported by the New England Journal of Medicine see their website for more.

An estimated 1-5% of the tested population have a positive fecal occult blood test. Of those, about 2-10% have cancer, while 20-30% have adenomas. Adenoma refers to a collection of growths (-oma) of glandular origin. ...

Causes for a positive test are:

• 2-10%: cancer (colorectal cancer, gastric cancer)
• 20-30% adenoma or polyps
• Bleeding peptic ulcer
• Angiodysplasia of the colon

Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to invade other tissues, either by direct growth into adjacent tissue through invasion or by implantation into distant sites by metastasis. ... Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. ... In medicine, stomach cancer (also called gastric cancer) can develop in any part of the stomach and may spread throughout the stomach and to other organs. ... Polyp of sigmoid colon as revealed by colonoscopy. ... Peptic ulcer is usually a non-malignant ulcer of the stomach (called gastric ulcer) or duodenum (called duodenal ulcer). ... An angiodysplasia in the colon being treated with argon plasma coagulation administered via probe through the colonoscope. ...

Sources

• Family practice notes on fecal occult blood testing.
• [1] for the DNA based PreGen-Plus® information sheet from The New England Journal of Medicine.

See also

• Blood in stool
• Digital rectal examination
• PreGen-Plus®

In medicine, when refering to human feces, Blood in stool can refer to several distinct conditions: Melena Fecal occult blood Hematochezia In infants, the Apt test can be used to distinguish Fetal hemoglobin from maternal blood. ... A rectal examination or rectal exam is an internal examination of the rectum by a physician. ...

External links

• NIH/Medline
• Mayo Clinic
• Cleveland Clinic