Meconium staining occurs in about 13 percent of live births, and up to 12 percent of these develop meconium aspiration syndrome. Some studies have advocated intratracheal suctioning to prevent meconium aspiration syndrome, and this technique was widely adopted in the 1980s. More recent studies suggest that intratracheal suctioning may not be necessary in all cases of meconium aspiration. Wiswell and colleagues conducted a randomized controlled trial to determine whether intratracheal suctioning reduced the incidence of meconium aspiration syndrome in vigorous newborns, and to determine the frequency of complications associated with this procedure.

Twelve centers enrolled patients in this study. Neonates who were included had a gestational age of at least 37 weeks and appeared to be vigorous (i.e., had spontaneous respirations, a heart rate of at least 100 beats per minute and reasonable tone) in the delivery room. The other inclusion criterion was the presence of meconium in the amniotic fluid, regardless of the consistency of the fluid. Infants were randomly assigned to the intubation and intratracheal suctioning (INT) group or the expectant management (EXP) group. The INT group received intubation plus suctioning (via wall suctioning with 80 to 120 mm negative pressure), with the suctioning repeated until no more meconium was retrieved. Infants in the EXP group were allowed to be intubated and suctioned if they developed respiratory distress but were not routinely treated in this manner.

The INT group included 1,051 infants and the EXP group included 1,043. There were no differences between the groups in terms of five-minute Apgar scores, although the INT group was significantly more likely to have lower one-minute Apgar scores. Three percent of meconium-stained babies were diagnosed with meconium aspiration syndrome, and 4.2 percent were diagnosed with other problems, such as transient tachypnea of the newborn or pneumonia. In the INT group, 3.2 percent of infants developed meconium aspiration syndrome, compared with 2.7 percent in the EXP group, an insignificant difference. Although infants born through thick meconium were more likely to develop meconium aspiration syndrome, suctioning provided no advantage over expectant management in preventing this condition or other respiratory illnesses. In the EXP group, 6.1 percent of the infants were intubated and suctioned because of respiratory distress or evidence of meconium blockage of the airway. Six percent of these infants developed meconium aspiration syndrome.

Of all of the infants who were intubated (in both groups), 3.8 percent had complications related to the procedure. Most of these complications resolved within 60 seconds, although some cases of hoarseness lasted up to 12 hours. Analysis showed that infants born via vaginal delivery were less likely to develop meconium aspiration syndrome than those born via cesarean section. Mothers who had received fewer than five prenatal visits were also more likely to have infants who developed meconium aspiration syndrome. There was a more than three-fold increase in meconium aspiration syndrome development if oropharyngeal suctioning did not occur before delivery of the shoulders. Specifically, meconium aspiration syndrome occurred in 8.5 percent of infants not suctioned (oropharyngeally, on the perineum) versus 2.7 percent of those infants who were thus suctioned.

Catheter suctioning and bulb-syringe suctioning were both effective; no differences were seen between infants in whom these types of suctioning were used in the occurrence of respiratory symptoms and illnesses. Infants with meconium in the trachea (as determined after intubation) were more likely to develop meconium aspiration syndrome.

The authors conclude that expectant management of a meconium-stained neonate who appears vigorous is not more likely than intubation and suctioning of such an infant to lead to meconium aspiration syndrome or other respiratory problems. Because the complication rate of intubation and suctioning is low, this procedure should still be performed in a meconium-stained neonate who is not vigorous or who develops respiratory distress.

editor's note: This large, well-designed study should reassure physicians caring for neonates. Only if a vigorous, meconium-stained newborn develops respiratory symptoms of distress should intubation and suctioning be necessary.—g.b.h.