Human feces (or faeces; Latin: fæx), also known as stool, is the waste product of the human digestive system including bacteria. It varies significantly in appearance, according to the state of the digestive system, diet and general health. Normally stool is semisolid, with a mucus coating. Small pieces of harder, less moist feces can sometimes be seen impacted on the distal (leading) end. This is a normal occurrence when a prior bowel movement is incomplete, and feces are returned from the rectum to the intestine, where water is absorbed. Meconium (sometimes erroneously spelled merconium) is a newborn baby's first feces.
Human fecal matter varies significantly in appearance, depending on diet and health.
Human feces ordinarily has a light to dark brown coloration, which results from a combination of bile and bilirubin that is derived from dead red blood cells. Normally it is semisolid, with a mucus coating.
Feces can be black due to the presence of red blood cells that have been in the intestines long enough to be broken down by digestive enzymes. This is known as melena, and is typically due to bleeding in the upper digestive tract, such as from a bleeding peptic ulcer. Conditions that can also cause blood in the stool include hemorrhoids, anal fissures, diverticulitis, colon cancer, and ulcerative colitis. The same color change can be observed after consuming foods that contain a substantial proportion of animal blood, such as black pudding or tiết canh. Black feces can also be caused by a number of medications, such as bismuth subsalicylate (the active ingredient in Pepto-Bismol), and dietary iron supplements, or foods such as beetroot, black liquorice, or blueberries.
Hematochezia is similarly the passage of feces that are bright red due to the presence of undigested blood, either from lower in the digestive tract, or from a more active source in the upper digestive tract. Alcoholism can also provoke abnormalities in the path of blood throughout the body, including the passing of red-black stool.
Prussian blue, used in the treatment of radiation, cesium, and thallium poisoning, can turn the feces blue. Substantial consumption of products containing blue food dye, such as blue curaçao or grape soda, can have the same effect.
Feces can be green due to having large amounts of unprocessed bile in the digestive tract and strong-smelling diarrhea. This can occasionally be the result from eating liquorice candy, as it is typically made with anise oil rather than liquorice herb and is predominantly sugar. Excessive sugar consumption or a sensitivity to anise oil may cause loose, green stools.
Feces possess physiological odor, which can vary according to diet (especially the amount of meat protein e.g., methionine) and health status. The odor of human feces is suggested to be made up from the following odorant volatiles:
Attempts to reduce the odor of feces (and flatus) are largely based on animal research carried out with industrial applications, such as reduced environmental impact of pig farming. See also: Flatulence#Management, odor. Many dietary modifications/supplements have been researched, including:
Activated charcoal. (Note this study concluded activated charcoal at a dose of 0.52g four times a day did not appreciably influence the liberation of fecal gases).
In Islam, washing of the anus with water (using the left hand) is mandatory. If water is not available, items such as paper, stones, or dried leaves can be used.
In India, the anus is also washed with water using the left hand.
In the United Kingdom, the Indian toilet was adapted as the "WC" (water closet) and widely deployed in England during the reign of Queen Victoria. London suffered numerous outbreaks of food poisoning resulting from workers handling food after using the toilet. Cleansing of the anus was an arbitrary practice left to personal choice and facilities available.
In Ancient Rome, a communal sponge was employed. It was rinsed in a bucket of salt water after use.
In Japan, flat sticks were used in ancient times, being replaced by toilet paper as the country became more Westernized. Toilets that include built-in bidets have now become widely popular in private homes; these can be very sophisticated appliances, allowing users to adjust the temperature, direction and force of water jets, and offering warm air to dry the anus and surrounding regions. The toilet flushes automatically when the buttocks leave the seat.
The Bristol stool scale is a medical aid designed to classify the form of human feces into seven categories. Sometimes referred to in the UK as the "Meyers Scale," it was developed by K. W. Heaton at the University of Bristol and was first published in the Scandinavian Journal of Gastroenterology in 1997. The form of the stool depends on the time it spends in the colon.
The seven types of stool are:
Separate hard lumps, like nuts (hard to pass)
Sausage-shaped but lumpy
Like a sausage but with cracks on the surface
Like a sausage or snake, smooth and soft
Soft blobs with clear-cut edges
Fluffy pieces with ragged edges, a mushy stool
Watery, no solid pieces. Entirely Liquid
Types 1 and 2 indicate constipation. Types 3 and 4 are optimal, especially the latter, as these are the easiest to pass. Types 5–7 are associated with increasing tendency to diarrhea or urgency.
Diarrhea is the condition of having three or more loose or liquid bowel movements per day. This condition can be a symptom of injury, disease or foodborne illness and is usually accompanied by abdominal pain. There are other conditions which involve some but not all of the symptoms of diarrhea, and so the formal medical definition of diarrhea involves defecation of more than 200 grams per day (though formal weighing of stools to determine a diagnosis is never actually carried out).
It occurs when insufficient fluid is absorbed by the colon. As part of the digestion process, or due to fluid intake, food is mixed with large amounts of water. Thus, digested food is essentially liquid prior to reaching the colon. The colon absorbs water, leaving the remaining material as a semisolid stool. If the colon is damaged or inflamed, however, absorption is inhibited, and watery stools result.
Diarrhea is most commonly caused by myriad viral infections but is also often the result of bacterial toxins and sometimes even infection. In sanitary living conditions and with ample food and water available, an otherwise healthy patient typically recovers from the common viral infections in a few days and at most a week. However, for ill or malnourished individuals diarrhea can lead to severe dehydration and can become life-threatening without treatment.
A quick test for fecal contamination of water sources or soil is a check for the presence of E. colibacteria performed with the help of MacConkey agar plates or Petri dishes. E. coli bacteria uniquely develop red colonies at temperature of approximately 43 °C (109 °F) overnight. Although most strains of E. coli are harmless, their presence is indicative of fecal contamination, and hence an increased possibility of the presence of more dangerous organisms.
^Hiele, M; Ghoos, Y; Rutgeerts, P; Vantrappen, G; Schoorens, D (June 1991). "Influence of nutritional substrates on the formation of volatiles by the fecal flora.". Gastroenterology100 (6): 1597–602. PMID2019366.Cite uses deprecated parameters (help)
^ abcTangerman, A (Oct 15, 2009). "Measurement and biological significance of the volatile sulfur compounds hydrogen sulfide, methanethiol and dimethyl sulfide in various biological matrices.". Journal of chromatography. B, Analytical technologies in the biomedical and life sciences877 (28): 3366–77. doi:10.1016/j.jchromb.2009.05.026. PMID19505855.
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^Bartlett, John G.; Gerding, Dale N. (15 January 2008). "Clinical Recognition and Diagnosis of Infection". Clinical Infectious Diseases46 (s1): S12–S18. doi:10.1086/521863.
^Suarez, FL; Furne, J; Springfield, J; Levitt, MD (January 1999). "Failure of activated charcoal to reduce the release of gases produced by the colonic flora.". The American journal of gastroenterology94 (1): 208–12. doi:10.1111/j.1572-0241.1999.00798.x. PMID9934757.Cite uses deprecated parameters (help)
^Suarez, FL; Furne, JK; Springfield, J; Levitt, MD (May 1998). "Bismuth subsalicylate markedly decreases hydrogen sulfide release in the human colon.". Gastroenterology114 (5): 923–9. doi:10.1016/s0016-5085(98)81700-9. PMID9558280.Cite uses deprecated parameters (help)
^ abGiffard, CJ; Collins, SB; Stoodley, NC; Butterwick, RF; Batt, RM (Mar 15, 2001). "Administration of charcoal, Yucca schidigera, and zinc acetate to reduce malodorous flatulence in dogs.". Journal of the American Veterinary Medical Association218 (6): 892–6. doi:10.2460/javma.2001.218.892. PMID11294313.Cite uses deprecated parameters (help)