{{short description|Solid mineral mass formed in the gastrointestinal system}} {{other uses|calculus (medicine)}} {{Infobox medical condition (new) | name = Enterolith | synonyms = | image = | caption = | pronounce = | field = | symptoms = | complications = | onset = | duration = | types = | causes = | risks = | diagnosis = | differential = | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }}
An '''enterolith''' is a mineral [[concretion]] or [[Calculus (medicine)|calculus]] formed anywhere in the [[gastrointestinal system]]. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum [[watchful waiting]]. If there is evidence of complications, they must be removed. An enterolith may form around a ''nidus'', a small [[Foreign body|foreign object]] such as a seed, pebble, or piece of twine that serves as an irritant. In this respect, an enterolith forms by a process similar to the [[Pearl#Creation|creation of a pearl]]. An enterolith is not to be confused with a [[gastrolith]], which helps digestion.
==In equines== [[Equine]] enteroliths are found by walking pastures or turning over manure compost piles to find small enteroliths, during [[necroscopy]], and increasingly, during surgery for [[colic]]. Therefore, the incidence of asymptomatic enteroliths is unknown.
Equine enteroliths are typically smoothly spherical or tetrahedral,<ref name="Blue1979"/> consist mostly of the mineral [[struvite]]<ref name="Blue1979">{{cite journal| author = Blue MG| title = Enteroliths in horses--a retrospective study of 30 cases| journal = Equine Veterinary Journal| volume = 11| issue = 2| pages = 76–84|date=April 1979| pmid = 477649| doi = 10.1111/j.2042-3306.1979.tb01307.x}}</ref><ref name="pmid7251465">{{cite journal|vauthors=Blue MG, Wittkopp RW | title = Clinical and structural features of equine enteroliths| journal = Journal of the American Veterinary Medical Association| volume = 179| issue = 1| pages = 79–82|date=July 1981| pmid = 7251465}}</ref> ([[ammonium]] [[magnesium]] [[phosphate]]), and have concentric rings of mineral precipitated around a nidus.<ref name="Blue1979"/><ref name="Lloyd+1987">{{cite journal|vauthors=Lloyd K, Hintz HF, Wheat JD, Schryver HF | title = Enteroliths in horses| journal = The Cornell Veterinarian| volume = 77| issue = 2| pages = 172–86|date=April 1987| pmid = 3552440}}</ref>
Enteroliths in [[horse]]s were reported widely in the 19th century, infrequently in the early 20th century, and now increasingly. They have also been reported in [[zebra]]s: five in a [[zoo]] in [[California]]<ref>{{cite journal|vauthors=McDuffee LA, Dart AJ, Schiffman P, Parrot JJ | title = Enterolithiasis in two zebras| journal = Journal of the American Veterinary Medical Association| volume = 204| issue = 3| pages = 430–2|date=February 1994| doi = 10.2460/javma.1994.204.03.430| pmid = 8150704}}</ref> and one in a zoo in [[Wisconsin]].<ref>{{cite journal|vauthors=Decker RA, Randall TL, Prideauz JW | title = Enterolithiasis in a confined Hartman's mountain zebra| journal = Journal of Wildlife Diseases| volume = 11| issue = 3| pages = 357–9|date=July 1975| pmid = 1152174| doi = 10.7589/0090-3558-11.3.357| s2cid = 2419057| url = http://www.jwildlifedis.org/cgi/pmidlookup?view=long&pmid=1152174| url-access = subscription}}</ref> Struvite enteroliths are associated with elevated [[pH]] and mineral concentrations in the [[Lumen (anatomy)|lumen]].<ref>{{cite journal|vauthors=Hassel DM, Rakestraw PC, Gardner IA, Spier SJ, Snyder JR | title = Dietary risk factors and colonic pH and mineral concentrations in horses with enterolithiasis| journal = Journal of Veterinary Internal Medicine| volume = 18| issue = 3| pages = 346–9| year = 2004| pmid = 15188822| doi = 10.1111/j.1939-1676.2004.tb02556.x| doi-access = free}}</ref> In [[California]], struvite enteroliths are associated also with a high proportion of [[alfalfa]] in the feed and less access to grass pasture. This association has been attributed to the cultivation of alfalfa on [[serpentine soil]]s, resulting in high concentrations of [[magnesium]] in the alfalfa.{{Citation needed|date=October 2008}}
==In humans== In [[human]]s, enteroliths are rare and may be difficult to distinguish from [[gall stone]]s. Their chemical composition is diverse, and rarely can a nidus be found. A [[differential diagnosis]] of an enterolith requires the enterolith, a normal gallbladder, and a [[diverticulum]].<ref>{{cite journal|vauthors=Yang HK, Fondacaro PF | title = Enterolith ileus: a rare complication of duodenal diverticula| journal = The American Journal of Gastroenterology| volume = 87| issue = 12| pages = 1846–8|date=December 1992| pmid = 1449155}}</ref><ref>{{cite journal|vauthors=Chuang JH, Chan HM, Huang YS, Hsieh JS, Huang TJ | title = Enterolith ileus as a complication of duodenal diverticulosis--one case report and review of the literature| journal = Gaoxiong Yi Xue Ke Xue Za Zhi| volume = 9| issue = 8| pages = 488–93|date=August 1993| pmid = 8230370}}</ref>
An enterolith typically forms within a [[diverticulum]]. An enterolith formed in a [[Meckel's diverticulum]] sometimes is known as a Meckel's enterolith. Improper use of [[magnesium oxide]] as a ''long-term'' [[laxative]] has been reported to cause enteroliths and/or [[Bezoar|medication bezoar]]s.<ref>{{cite journal |vauthors=Tatekawa Y, Nakatani K, Ishii H, etal | title = Small bowel obstruction caused by a medication bezoar: report of a case| journal = Surgery Today| volume = 26| issue = 1| pages = 68–70| year = 1996| pmid = 8680127| doi = 10.1007/BF00311997| s2cid = 24976010}}</ref>
Most enteroliths are not apparent and cause no complications. However, any complications that do occur are likely to be severe. Of these, [[bowel obstruction]] is most common,<ref>{{cite journal|vauthors=Gamblin TC, Glenn J, Herring D, McKinney WB | title = Bowel obstruction caused by a Meckel's diverticulum enterolith: a case report and review of the literature| journal = Current Surgery| volume = 60| issue = 1| pages = 63–4| year = 2003| pmid = 14972313| doi = 10.1016/S0149-7944(02)00650-5}}</ref> followed by [[ileus]]<ref name="Steenvoorde+2003">{{cite journal|vauthors=Steenvoorde P, Schaardenburgh P, Viersma JH | title = Enterolith ileus as a complication of jejunal diverticulosis: two case reports and a review of the literature| journal = Digestive Surgery| volume = 20| issue = 1| pages = 57–60| year = 2003| pmid = 12637808| doi = 10.1159/000068852| s2cid = 20592835}}</ref> and [[gastrointestinal perforation|perforation]]. Bowel obstruction and ileus typically occur when a large enterolith is expelled from a diverticulum into the [[Lumen (anatomy)|lumen]]. Perforation typically occurs within the diverticulum.{{citation needed|date=August 2020}}
On plain X-rays, the visibility of the enterolith depends on its calcium content. Calcium-rich stones usually demonstrate a radiodense rim and a relatively radioluscent core. Choleic acid stones are almost always radiolucent. They sometimes can be visualized on CT scans without contrast; presence of contrast in the lumen may reveal the enterolith as a void. Most often, they are visualized using ultrasound.{{cn|date=October 2023}}
Although recent surveys of enterolith composition are lacking, one early review notes struvite (as in equines), [[calcium phosphate]], and [[calcium carbonate]] and reports [[choleic acid]].<ref name="Raper1921">{{cite journal| author = Raper HS| title = A Human Enterolith containing Choleic Acid| journal = The Biochemical Journal| volume = 15| issue = 1| pages = 49–52| year = 1921| pmid = 16742974| pmc = 1258956| doi = 10.1042/bj0150049}}</ref> [[Deoxycholic acid]] and [[cholic acid]] have also been reported.<ref>{{cite journal|vauthors=Fantl P, Rollo AJ, Strosberg H | title = Chemical analysis of an enterolith| journal = Gut| volume = 6| issue = 4| pages = 384–6|date=August 1965| pmid = 4953381| pmc = 1552302| doi = 10.1136/gut.6.4.384}}</ref>
===Treatment=== In simple cases of obstruction, where there are no complications, a variety of non-surgical and surgical techniques are used to remove the enterolith.<ref name="Steenvoorde+2003"/> These include crushing the enterolith and milking it back to the stomach or forward to the colon, surgical removal via an uninvolved segment of the gastrointestinal tract, and [[Segmental resection|resection]] of the involved segment.{{citation needed|date=August 2020}}
==See also== * [[Acid-base physiology]] * [[Bezoar]]
==References== {{Reflist}} == External links == {{Medical resources | ICD10 = {{ICD10|K|56|4}} | ICD9 = {{ICD9|560.39}} | ICDO = | MedlinePlus = | eMedicineSubj = | eMedicineTopic = | MeshID = | SNOMED CT = 40515007 }} {{wiktionary|enterolith|nidus}} [[Category:Rare diseases]] [[Category:Gastrointestinal tract disorders]]