MECONIUM AND AMNIOTIC FLUID

Meconium is the residue of swallowed cellular debris, cells sloughed along the fetal gastrointestinal tract and secretions from the hepato-biliary system. While residing in the terminal colon and rectum, meconium has a semisolid paste-like consistency. When expelled into the amniotic cavity it slowly breaks up and distributes as particles of varying size throughout the amniotic fluid. Meconium accumulates in the distal colon and rectum with advancing gestation and may actually distend these structures at term.

The distribution of meconium within the fetal gut has been advocated as a means of assessment of fetal age, however this is not a specific sign and is rarely used in clinical practice.

Little is known about the regulation and control of peristalsis and why meconium moves along the gut to the rectum but is not usually expelled. Why the distal colon is so inactive prior to birth is unknown as most newborns pass meconium shortly after birth, and most fetal organs systems function in utero (1).

• Regulation and control of passage of meconium.
• Fetal asphyxia and meconium passage.
• Neonatal asphyxia and meconium passage.

ULTRASOUND

Link to Ultrasound of Meconium.

Echogenic meconium due to the passage of meconium

in utero. This was the pump twin of an acardiac twin

pregnancy that became stressed at 39 wks GA

REFERENCES

1. Manning FA.(ed). In: Fetal Medicine. Principles and practice. Amniotic fluid (Chapter 9). Appleton and Lange, Norwalk, Connecticut 1995:188-189.