View source for Meconium

{{Short description|Earliest feces of a mammalian infant}}
{{For|the historical meaning of the term|Opium}}
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{{Infobox medical condition (new)
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| caption       = Meconium from 12-hour-old [[newborn]]{{snd}}the baby's third [[bowel movement]]<br/><hr/>Scale: 5 cm left to right.
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'''Meconium''' is the earliest [[feces|stool]] of a mammalian [[infant]] resulting from [[defecation]]. Unlike later feces, meconium is composed of materials ingested during the time the infant spends in the [[uterus]]: intestinal [[epithelial cells]], [[lanugo]], [[mucus]], [[amniotic fluid]], [[bile]], and water. Meconium, unlike later feces, is viscous and sticky like tar – its color usually being a very dark olive green and it is almost odorless.<ref>Persis Mary Hamilton, ''Basic Pediatric Nursing'' (Maryland Heights MO: Mosby, 1991), 82. {{ISBN|978-0801658693}}</ref> When diluted in amniotic fluid, it may appear in various shades of green, brown, or yellow. It should be completely passed by the end of the first few days after birth, with the stools progressing toward yellow (digested milk).

== Clinical significance ==

=== Meconium in amniotic fluid ===
Meconium is normally retained in the infant's bowel until after birth, but sometimes it is expelled into the [[amniotic fluid]] prior to birth or during [[childbirth|labor and delivery]]. The stained amniotic fluid is recognized by medical staff as a possible sign of [[fetal distress]]. Some [[postterm pregnancy|post-dates pregnancies]] (when they are more than 40 weeks pregnant) may also have meconium-stained amniotic fluid without fetal distress. Medical staff may aspirate the meconium from the nose and mouth of a newborn immediately after delivery in the event the baby shows signs of respiratory distress to decrease the risk of [[meconium aspiration syndrome]], which can occur in meconium-stained amniotic fluid.

Most of the time that the amniotic fluid is stained with meconium, it will be homogeneously distributed throughout the fluid, making it brown. This indicates that the fetus passed the meconium some time ago such that sufficient mixing occurred as to establish the homogeneous mixture. Terminal meconium occurs when the fetus passes the meconium a short enough time before birth/cesarean section that the amniotic fluid remains clear, but individual clumps of meconium are in the fluid.

=== Failure to pass meconium ===
{{anchor|Meconium ileus}}
The failure to pass meconium is a symptom of several diseases including [[Hirschsprung's disease]] and [[cystic fibrosis]].

The meconium sometimes becomes thickened and congested in the [[intestines]], a condition known as '''meconium ileus'''. Meconium ileus is often the first sign of [[cystic fibrosis]].<ref>{{cite book |last=Hutchinson |first=James H |name-list-style=vanc |date=1975 |title=Practical Paediatric Problems |edition=4th |publisher=Lloyd-Luke |location=London |isbn=0-85324-114-7 |page=[https://archive.org/details/practicalpaediate4hutc/page/314 314] |url=https://archive.org/details/practicalpaediate4hutc/page/314 |url-access=registration}}</ref> In cystic fibrosis, the meconium can form a bituminous black-green mechanical obstruction in a segment of the ileum. Beyond this, there may be a few separate grey-white globular pellets. Below this level, the bowel is a narrow and empty micro-colon. Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. No meconium is passed, and abdominal distension and vomiting appear soon after birth. About 20% of cases of cystic fibrosis present with meconium ileus, while approximately 20% of one series of cases of meconium ileus did not have cystic fibrosis.<ref>{{cite web |last=Hekmatnia |first=Ali |name-list-style=vanc |title=Meconium Ileus |url=http://www.emedicine.com.radio/topic427.htm }}{{Dead link|date=March 2020 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The presence of meconium ileus is not related to the severity of the cystic fibrosis.<ref>{{cite book |last=Jones |first=Peter G |name-list-style=vanc |date=1976 |title=Clinical Paediatric Surgery |edition=2nd |publisher=Blackwell |location=Oxford |isbn=0-632-00089-9 |pages=74–75}}</ref> The obstruction can be relieved in a number of ways.<ref>{{cite web |vauthors=Irish M |veditors=Minkes RK |date=29 December 2015 |title=Surgical Aspects of Cystic Fibrosis and Meconium Ileus |url=http://www.emedicine.com/ped/topic2995.htm |access-date=25 October 2007 |archive-date=30 April 2003 |archive-url=https://web.archive.org/web/20030430140856/http://www.emedicine.com/ped/topic2995.htm |url-status=live }}</ref>

Meconium ileus should be distinguished from meconium plug syndrome, in which a tenacious mass of mucus prevents the meconium from passing and there is no risk of intestinal perforation. Meconium ileus has a significant risk of intestinal perforation. In a barium enema, meconium plug syndrome shows a normal or dilated colon as compared to micro-colon in meconium ileus.

=== Testing meconium for drugs ===
Meconium can be tested for various drugs, to check for ''in utero'' exposure. Using meconium, a Canadian research group showed that by measuring a by-product of [[ethanol|alcohol]], fatty acid ethyl esters (FAEE), they could objectively detect excessive maternal alcohol consumption during pregnancy.<ref>Chan D, Knie B, Boskovic R, [[Gideon Koren|Koren G.]] Placental handling of fatty acid ethyl esters: perfusion and subcellular studies. J Pharmacol ExpTher 2004; 310: 75-82.</ref> 

In the US, the results of meconium testing may be used by [[child protective services]] and other [[law enforcement agency|law enforcement agencies]] if the capacity of the parents to look after their child is in question.<ref>''G.B. v. Dearborn County Div. of Family and Children'', 754 N.E.2d 1027 (Ind.Ct.App., 2001).</ref> Meconium can also be analyzed to detect the tobacco use of mothers during their pregnancy, which is commonly under-reported.<ref name="pmid20799929">{{cite journal |display-authors=6 |vauthors=Braun JM, Daniels JL, Poole C, Olshan AF, Hornung R, Bernert JT, Xia Y, Bearer C, Barr DB, Lanphear BP |date=August 2010 |title=A prospective cohort study of biomarkers of prenatal tobacco smoke exposure: the correlation between serum and meconium and their association with infant birth weight |journal=Environmental Health: A Global Access Science Source |doi=10.1186/1476-069X-9-53 |pmc=2944243 |pmid=20799929 |volume=9 |issue=1 |pages=53 |doi-access=free |bibcode=2010EnvHe...9...53B }}
*{{lay source |template = cite press release|url= https://www.sciencedaily.com/releases/2010/08/100827082153.htm|title = Baby's first full diaper can reveal mother's smoking|date = August 27, 2010 |website = sciencedaily.com }}</ref>

== Sterility ==
The issue of whether meconium is sterile remains debated and is an area of ongoing research. Although some researchers have reported evidence of bacteria in meconium,<ref>{{cite journal |vauthors=Jiménez E, Marín ML, Martín R, Odriozola JM, Olivares M, Xaus J, Fernández L, Rodríguez JM |date=April 2008 |title=Is meconium from healthy newborns actually sterile? |journal=Research in Microbiology |doi=10.1016/j.resmic.2007.12.007 |pmid=18281199|volume=159 |issue=3 |pages=187–93|doi-access=free }}</ref> this has not been consistently confirmed. Other researchers have raised questions about whether these findings may be due to contamination after sample collection and that meconium is, in fact, sterile until after birth.<ref>{{cite journal |vauthors=Perez-Muñoz ME, Arrieta MC, Ramer-Tait AE, Walter J |date=April 2017 |title=A critical assessment of the 'sterile womb' and 'in utero colonization' hypotheses: implications for research on the pioneer infant microbiome |journal=Microbiome |doi=10.1186/s40168-017-0268-4 |pmc=5410102 |pmid=28454555 |volume=5 |issue=1 |pages=48 |doi-access=free }}</ref> Further researchers have hypothesized that there may be bacteria in the womb, but these are a normal part of pregnancy and could have an important role in shaping the developing immune system and are not harmful to the baby.<ref>{{cite journal |vauthors=Willyard C |date=January 2018 |title=Could baby's first bacteria take root before birth? |journal=Nature |bibcode=2018Natur.553..264W |doi=10.1038/d41586-018-00664-8 |pmid=29345664 |volume=553 |issue=7688 |pages=264–266|doi-access=free }}</ref>

== Etymology ==
The [[Latin]] term ''meconium'' derives from [[Greek language|Greek]] {{lang|grc|μηκώνιον}}, ''mēkōnion'', a diminutive of {{lang|grc|μήκων}}, ''mēkōn'' '[[poppy]]', in reference either to its tar-like appearance that may resemble some raw [[opium]] preparations or to [[Aristotle]]'s belief that it induces sleep in the fetus.<ref>{{cite web |last=O'Dochartaigh |first=Simon |name-list-style=vanc |title=HON Mother & Child Glossary, Meconium |website=www.hon.ch |url=http://www.hon.ch/Dossier/MotherChild/labor_complications/birth_meconium.html |access-date=17 April 2018 |archive-date=1 May 2021 |archive-url=https://web.archive.org/web/20210501220607/https://www.hon.ch/Dossier/MotherChild/labor_complications/birth_meconium.html |url-status=dead }}</ref><ref>{{LSJ|mhkw/nion|μηκώνιον|ref}}.</ref><ref>{{cite dictionary |title=meconium |dictionary=[[Online Etymology Dictionary]] |url=http://www.etymonline.com/index.php?term=meconium&allowed_in_frame=0 |access-date=2013-11-06 |archive-date=2017-08-21 |archive-url=https://web.archive.org/web/20170821214823/http://www.etymonline.com/index.php?term=meconium&allowed_in_frame=0 |url-status=live }}</ref>

==Other uses==
* In biology, meconium describes the [[metabolic]] waste product from the pupal stage of an insect that is expelled through the anal opening of the adult upon [[Pupa#Emergence|eclosion]] from the [[pupa]]. Other insects, such as [[beetle]]s and some [[Hymenoptera]] ([[Aculeata]]) expel the meconium at the end of the larval stage, before becoming a [[pupa]].

== Gallery ==
<gallery class="center" widths="220px" heights="160px">
file:mekonium.jpg|Newborn evacuating meconium.
Image:Meconium_Diaper.jpg|Meconium from 13-hour-old newborn.
File:Meconium vs poo.jpg|This image compares the appearance of meconium (from 48 hours after normal delivery at term) to the appearance of the same infant's feces after 1 week of breastfeeding.
</gallery>

== References ==
{{Reflist}}

== External links ==
* {{Commons category-inline}}

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[[Category:Feces]]
[[Category:Human physiology]]
[[Category:Neonatology]]