Meconium

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

Introduction

Meconium is the first stool passed by an infant, typically within the first 24 to 48 hours after birth. It is a thick, green, sticky substance that is produced in the intestines of the fetus and differs significantly from feces passed later in life.

Composition

Meconium is made up of materials the fetus has ingested while in utero. These include intestinal epithelial cells, lanugo (fine, soft hair that covers the fetus's body), mucus, amniotic fluid, water, and bile, a digestive fluid produced by the liver. Contrary to normal feces, meconium lacks any microbial constituents as the fetal intestines have not yet been colonized by bacteria.

Appearance and Texture

Meconium's color ranges from very dark olive green to black, largely due to the presence of bile. Its consistency is viscous and sticky, often compared to tar. When mixed with amniotic fluid, it may take on various shades of green, brown, or yellow.

Passage

Typically, a newborn will pass meconium in the first few days following birth. The transition from meconium to normal stool is marked by a change in color and consistency, as the stool becomes less sticky and more yellow - a reflection of digested breast milk or formula.

Clinical Significance

Meconium's presence in the amniotic fluid, a condition known as meconium-stained amniotic fluid (MSAF), can indicate fetal distress during labor and delivery. If the meconium is aspirated into the infant's lungs, it can cause meconium aspiration syndrome, a severe respiratory condition.

Gallery

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  Meconium from 13-hour-old newborn.

• 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

Meconium Resources
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