Meconium Aspiration Syndrome Clinical Presentation

Updated: Mar 20, 2017
  • Author: Gina M Geis, MD; Chief Editor: Ted Rosenkrantz, MD  more...
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Presentation

History

The presence of meconium in amniotic fluid is required to cause meconium aspiration syndrome (MAS), but not all neonates with meconium-stained fluid develop this condition. The diagnosis of MAS requires the presence of meconium-stained amniotic fluid or neonatal respiratory distress, as well as characteristic radiographic abnormalities.

Historically, efforts to reduce the development of MAS included oropharyngeal suctioning at the perineum, followed by intubation and tracheal suction of meconium immediately following delivery. This universal practice was abandoned over a decade ago when studies showed that infants who were vigorous at birth did not benefit from this intervention. Following this practice change, the Neonatal Resuscitation Program (NRP) recommended intubation and tracheal suctioning only for nonvigorous infants born through meconium-stained fluid.

However, in 2015, these recommendations changed again: It is no longer recommended to intubate and suction nonvigorous infants born through meconium-stained fluid due to a lack of evidence to support this practice. [10, 11] Instead, in this setting, the NRP now recommends having a practitioner skilled at endotracheal intubation be present at the time of birth, and they should begin with the initial steps of resuscitation (ie, provide warmth, position the head and neck to open the airway, clear secretions with a bulb syringe, dry, and stimulate the infant). [10, 11]  The 2017 American College of Obstetricians and Gynecologists (ACOG) opinion number 689 indicates that, regardless of whether infants with meconium-stained amniotic fluid are vigorous or nonvigorous, do not routinely administer intrapartum suctioning. [11]

In a 2015 developing nation retrospective study (2008-2009) that evaluated the effect of intrapartum oropharyngeal suction on MAS in 509 meconium-stained, term singleton neonates without major congenital malformations, investigators found that outcomes in those who received suctioning were similar to those in the control group (who did not undergo suctioning). [12] The incidence and severity of MAS, as well as oxygen requirements longer than 48 hours, were comparable between the groups.

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Physical Examination

Severe respiratory distress may be present. Symptoms include the following:

  • Cyanosis

  • End-expiratory grunting

  • Alar (nasal) flaring

  • Intercostal retractions

  • Tachypnea

  • Barrel chest (increased anteroposterior diameter) due to the presence of air trapping

  • Auscultated rales and rhonchi (in some cases)

Yellow-green staining of fingernails, umbilical cord, and skin may be also observed.

Green urine may be noted in newborns with MAS less than 24 hours after birth. Meconium pigments can be absorbed by the lung and can be excreted in urine.

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