Elsevier

Clinics in Perinatology

Volume 34, Issue 4, December 2007, Pages 653-665
Clinics in Perinatology

Meconium Stained Fluid: Approach to the Mother and the Baby

https://doi.org/10.1016/j.clp.2007.10.005Get rights and content

Meconium aspiration syndrome (MAS) is a common problem that most pediatricians will encounter in the delivery room and normal newborn nursery. Approximately 13% of all live births are complicated by meconium stained amniotic fluid (MSAF). MAS is defined as respiratory distress in an infant born through MSAF whose symptoms cannot be otherwise explained. Optimal care for an infant born through MSAF involves cooperation between the obstetrician and pediatrician, each with separate but imperative roles.

Section snippets

Causes of meconium-stained amniotic fluid

Under normal circumstances, the passage of meconium from the fetus into the amnion is prevented by the lack of intestinal peristalsis, which is caused by several factors, including low motilin levels, tonic contraction of the anal sphincter, and a terminal cap of viscous meconium. MSAF may be a natural phenomenon that neither indicates nor causes fetal distress but simply reflects a postterm fetus with a mature gastrointestinal tract in which motilin levels have risen. Vagal stimulation

Mechanisms of injury

Meconium seems to be toxic to the lungs in many ways, and it may be difficult to determine which mechanisms predominate at a given point in time. Mechanisms of injury in MAS are as follows: (1) mechanical obstruction of airways, (2) chemical pneumonitis, (3) vasoconstriction of pulmonary vessels, and (4) inactivation of surfactant.

Diagnosis

MAS must be considered in any infant born through MSAF who develops symptoms of respiratory distress. The classic roentgenographic findings in MAS are described as diffuse, asymmetric patchy infiltrates, but because of the diverse mechanisms that cause disease, various radiographic findings may be present (Fig. 1). Frequently, overaeration is present, which may lead to air leak syndromes, such as pneumothorax, pneumomediastinum, or pulmonary interstitial emphysema (Fig. 2). A series of 80 cases

Antepartum management

The obstetric focus is on the possible need for intervention designed to decrease the risk of MAS. MSAF should be considered a possible warning sign of fetal distress. Many authors recommend that if MSAF is seen, obstetricians should monitor carefully the fetal heart rate tracing and have a low threshold for performing additional testing, such as fetal scalp pH [18].

A newer modality for monitoring the fetus is fetal pulse oximetry. Fetal pulse oximetry was approved for use by the Food and Drug

Intrapartum suctioning

Intrapartum suctioning, combined with intubation after delivery, has been considered standard procedure for more than 25 years based on the seminal work of Carson et al [29]. However, only recently has intrapartum suctioning been studied with randomized trials. The goal is to clear as much meconium as possible from the airway before the infant is able to take a breath. This is accomplished by suctioning the mouth, pharynx, and nose with either a large-bore suction catheter (12F–14F) or a bulb

Approach to the apparently well infant

Most infants born through MSAF require no interventions and may remain with their family in the delivery room. Because MAS does not always present immediately, however, it is important to monitor these infants closely for signs of respiratory distress. Infants at risk for MAS may have signs of postmaturity, such as peeling skin, long fingernails, and yellow stained skin and umbilical cord. One should observe the infant for tachypnea and cyanosis and for grunting, nasal flaring, and retractions.

Summary

Like many aspects of the perinatal period, optimal care of an infant born through MSAF involves collaboration between obstetrician and pediatrician, each with separate but important roles. As always, effective communication and anticipation of potential problems form the cornerstone of this partnership. Together the health of infants may be improved.

References (50)

  • B.S. Carson et al.

    Combined obstetric and pediatric approach to prevent meconium aspiration syndrome

    Am J Obstet Gynecol

    (1976)
  • N.E. Vain et al.

    Oroopharyngeal and nasopharyngeal suctioning of meconium-stained neonates before delivery of their shoulders: multicentre, randomised controlled trial

    Lancet

    (2004)
  • D.J. Janssen et al.

    Surfactant phosphatidylcholine metabolism inneonates with meconium aspiration syndrome

    J Pediatr

    (2006)
  • A. Lotze et al.

    Multicenter study of surfactant (beractant) use in the treatment of term infants with severe respiratory failure

    J Pediatr

    (1998)
  • J.P. Kinsella et al.

    Randomized, multicenter trial of inhaled nitric oxide and high-frequency oscillatory ventilation in severe, persistent pulmonary hypertension of the newborn

    J Pediatr

    (1997)
  • J.P. Kinsella et al.

    Low-dose inhalational nitric oxide in persistent pulmonary hypertension of the newborn

    Lancet

    (1992)
  • T.E. Wiswell

    Advances in the treatment of the meconium aspiration syndrome

    Acta Paediatr

    (2001)
  • H.M. Piper et al.

    Meconium: a marker for peripartum infection

    Obstet Gynecol

    (1998)
  • A. Greenough

    Surfactant replacement therapy for non-respiratory distress syndrome neonatal respiratory disease: research or clinical application?

    Eur J Pediatr

    (1995)
  • D. Moses et al.

    Inhibition of pulmonary surfactant function by meconium

    Am J Obstet Gynecol

    (1991)
  • G.M. Cleary et al.

    Exudative lung injury is associated with decreased levels of surfactant proteins in a rat model of meconium aspiration

    Pediatrics

    (1997)
  • S.T. Higgins et al.

    Meconium increases surfactant secretion in isolated rat alveolar type II cell

    Pediatr Res

    (1996)
  • R.D. Findlay et al.

    Surfactant replacement therapy for meconium aspiration syndrome

    Pediatrics

    (1996)
  • T.F. Yeh et al.

    Roentgenographic findings in infants with meconium aspiration syndrome

    JAMA

    (1979)
  • P. Valencia et al.

    Accuracy of admission chest x-ray (CXR) in the prediction of sickness severity in infants with meconium aspiration syndrome (MAS)

    Clin Res

    (1993)

    • Cited by (0)

    A version of this article appeared in Pediatric Clinics: Common Issues and Concerns in the Newborn Nursery, Part I (Volume 51, Issue 3, June 2004).

    View full text
    Copyright © 2004 Elsevier Inc. All rights reserved.