meconium aspiration syndrome
Also written as: MAS — meconium aspiration syndrome
A respiratory condition in newborns caused by inhalation of meconium-stained amniotic fluid, leading to airway obstruction and lung inflammation.
Full Definition
Meconium aspiration syndrome (MAS) is a serious respiratory condition that occurs when a newborn inhales meconium-stained amniotic fluid during delivery or in the immediate postnatal period. Meconium, the first bowel movement of a fetus, may be released into the amniotic fluid during periods of fetal stress, typically in post-term or compromised pregnancies. When aspirated, meconium can cause mechanical airway obstruction, chemical pneumonitis, and surfactant inactivation, leading to ventilation-perfusion mismatch, air leak syndromes, and persistent pulmonary hypertension. The condition presents with respiratory distress, tachypnea, and often requires aggressive respiratory management including mechanical ventilation, surfactant therapy, and in severe cases, extracorporeal membrane oxygenation (ECMO). Prevention strategies include appropriate management of post-term pregnancies and avoiding aggressive suctioning in vigorous meconium-stained infants.
Usage
Usage note: Distinguish from simple meconium staining; requires evidence of respiratory compromise for diagnosis.
In Context
- "The post-term infant developed meconium aspiration syndrome requiring high-frequency oscillatory ventilation and inhaled nitric oxide." — NICU progress note
- "Chest radiograph showed bilateral patchy infiltrates with hyperinflation consistent with meconium aspiration syndrome." — Neonatal radiology report