meconium constipation

The composition of meconium includes gastrointestinal secretions, bile, pancreatic secretions, various digestive enzymes, and lanugo, keratinized epithelial cells, calcium soap crystals formed from intestinal contents, inorganic salts, and derivatives such as fat, bile salts, and bilirubin that are swallowed in amniotic fluid and not absorbed. Meconium is dark green, sticky, unformed, and odorless. As gestational age increases, the amount of meconium increases and it moves downward, with the first meconium passage usually occurring within 12 hours after birth, or possibly delayed to 12–24 hours, and in very rare cases, defecation may not begin until 24–48 hours. If a newborn has not passed stool within 48 hours after birth due to thick meconium accumulating in the sigmoid colon and rectum, presenting with transient symptoms of low intestinal obstruction, this is termed meconium constipation.