Meconium

For the historical meaning of the term, see Opium.

Meconium from 12-hour-old newborn — the baby's third bowel movement. Scale: 5 cm left to right.

Meconium is the earliest stools of an infant. 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 is almost sterile,^[1] unlike later feces, is viscous and sticky like tar, and has no odor. It should be completely passed by the end of the first few days of life, with the stools progressing toward yellow (digested milk). The term Meconium derives from meconium-arion, meaning "opium-like", in reference either to its tarry appearance or to Aristotle's belief that it induces sleep in the fetus.^[2]

A symptom of both Hirschsprung's disease and cystic fibrosis is the failure to pass meconium.

Meconium is normally stored in the infant's bowel until after birth, but sometimes it is expelled into the amniotic fluid prior to birth or during labor and delivery. Meconium liquor is recognised by medical staff as a sign of fetal distress, and puts the neonate at risk of meconium aspiration.

Meconium can be tested for various drugs, to check for in utero exposure. Using meconium, a Canadian research group at the Hospital for Sick Children, University of Toronto, showed that by measuring a by-product of alcohol (FAEE) they could objectively detect babies exposed to excessive maternal drinking of alcohol in pregnancy.^[3] In the USA, the results of meconium-testing run on a newborn can be turned in to child protective services and other law enforcement agencies.^[4]

Terminal meconium

Most of the time that the amniotic fluid is stained with meconium it will be homogenously 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 homogenous mixture. Terminal meconium occurs when the fetus passes the meconium a short enough time before birth/caesarean section that the amniotic fluid remains clear, but individual clumps of meconium are in the fluid.

Meconium ileus

The meconium sometimes becomes thickened and congested in the ileum, a condition known as meconium ileus. Meconium ileus is often the first sign of cystic fibrosis.^[5] 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.^[6] The presence of meconium ileus is not related to the severity of the cystic fibrosis.^[7] The obstruction can be relieved in a number of different ways.^[8]

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.

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 eclosion from the pupa.

• Indication of Tobacco exposure.^[9]

See also

• Meconium aspiration syndrome (MAS), a condition in which infants take meconium into their lungs before or during delivery.

Gallery

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  Meconium from 13-hour-old newborn.

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  This image compares the appearance of meconium (from 48 hours after normal delivery at term) to the appearance of the same infant's faeces after 1 week of breastfeeding.

References

1. ^ JIMÉNEZ, Esther, et al. Is meconium from healthy newborns actually sterile? Research in Microbiology. Vol. 159, Issue 3, pp. 187-193.
2. ^ Health on the Net Foundation Mother and Child Glossary
3. ^ Chan D, Knie B, Boskovic R, Koren G. Placental handling of fatty acid ethyl esters: perfusion and subcellular studies. J Pharmacol ExpTher 2004; 310: 75-82.
4. ^ G.B. v. Dearborn County Div. of Family and Children, 754 N.E.2d 1027 (Ind.Ct.App., 2001).
5. ^ James H Hutchinson Practical Paediatric Problems 4th ed. London: Lloyd-Luke 1975 p. 314 ISBN 0-85324-114-7
6. ^ Ali Hekmatnia Meconium Ileus^{[dead link]}
7. ^ Peter G Jones Clinical Paediatric Surgery 2nd ed. Oxford: Blackwell 1976 pp 74-5 ISBN 0-632-00089-9
8. ^ Michael S Irish Surgical Aspects of Cystic Fibrosis and Meconium Ileus [1]
9. ^ http://www.sciencedaily.com/releases/2010/08/100827082153.htm