Meconium Ileus

Meconium

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 postpartum 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]

Hirschsprung's disease presents as failure to pass meconium.

Meconium is normally stored in the infant's intestines until after birth, but sometimes it is expelled into the amniotic fluid prior to birth or during labor and delivery.

Meconium can be tested for various drugs, to check for in utero exposure. 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.^[3]

Meconium ileus

The meconium sometimes becomes thickened and congested in the ileum, a condition known as meconium ileus. Meconium ileus is often the first symptom of cystic fibrosis.^[4] 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.^[5] The presence of meconium ileus is not related to the severity of the cystic fibrosis.^[6] The obstruction can be relieved in a number of different ways.^[7]

Meconium ileus should be distinguished from meconium plug syndrome, in which a tenacious mass of mucus prevents the meconium from passing.

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.