Meconium Aspiration Syndrome

  • meconium aspirationAspiration of meconium (the neonate’s first feces) into the lungs.
  • Typically occur with the first breath or while the neonate is in utero.
  • Thick, sticky, and greenish black substance; may be seen in the amniotic fluid after 34 weeks gestation.


  • Asphyxia in utero leads to increased fetal peristalsis, relaxation of the anal sphincter, passage of meconium into the amniotic fluid, and reflex gasping of amniotic fluid into the lungs.
  • Neonates with meconium aspiration syndrome (MAS) increase respiratory efforts to create greater negative intrathoractic pressures and improve air flow to the lungs.
  • Hyperinflation, hypoxemia, and academia cause increased peripheral vascular resistance.
  • Right-to-left shunting commonly follows.
  • Meconium creates a ball-valve effect, trapping air in the alveolus and preventing adequate gas exchange.
  • Chemical pneumonitis results, causing the alveolar walls and interstitial tissues to thicken, again preventing adequate gas exchange.
  • Cardiac efficiency can be compromised from pulmonary hypertension.


  • Commonly related to fetal distress during labor.
  • Advance gestational age (greater than 40 weeks)
    • Difficult delivery
    • Fetal distress
    • Intrauterine hypoxia
    • Maternal diabetes
    • Maternal hypertension
    • Poor intrauterine growth
    • Risk factors for MAS:

Assessment Findings

  • Fetal hypoxia as indicated by altered fetal activity and heart rate.
  • Dark greenish staining or streaking of the amniotic fluid noted on rupture of membranes.
  • Obvious presence of meconium in the amniotic fluid
  • Greenish staining of the neonate’s skin (if the meconium was passed long before delivery) or placenta.
  • Signs of distress at delivery, such as the neonate appearing limp, an Apgar score below 6, pallor, cyanosis, and respiratory distress.
  • Coarse crackles when auscultating the neonate’s lungs.

Test Results

  • Arterial blood gas analysis shows hypoxemia and decreased pH.
  • Chest X-ray may show patches or streaks of meconium in the lungs, air trapping, or hyperinflation.


  • Respiratory assistance via mechanical ventilation
  • Maintenance of a neutral thermal environment
  • Administration of surfactant and an antibiotic
  • Extracorporeal membrane oxygenation (in severe cases).

Nursing Interventions

  • During labor, continuously monitor the fetus for signs and symptoms of distress.
  • Immediately inspect any fluid passed with rupture of the membrane.
  • Assist with immediate endotracheal suctioning before the first breaths, as indicated.
  • Monitor lung status closely, including breath sounds and respiratory rate and character.
  • Frequently assess the neonate’s vital signs.
  • Administer treatment modalities, such as oxygen and respiratory support as ordered.
  • Institute measures to maintain a neutral thermal environment.
  • Provide the family with emotional support and guidance.

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

What Do You Think?