Meconium Aspiration
Meconium is the dark green material that is found in the
intestines of the unborn fetus. It is normally released as a
thick, dark green bowel movement at or right near the time of
birth. However, an infant who is stressed may pass some meconium
into the amniotic fluid before birth and breathe it into the lungs
(called aspiration).
Five to ten percent of all births have meconium staining of the
amniotic fluid. Infants who are post term, experience a difficult
delivery, or experience fetal distress and lack of oxygen during
delivery are at a higher risk for meconium aspiration.
Infants who experience a stressful labor may experience a lack of
oxygen. This, in turn, can cause the intestines to move and the
muscles surrounding the anus to relax, releasing the meconium into
the amniotic fluid. The fetus may gasp and breathe the thick
meconium into the lungs during labor, or the meconium enters when
the baby takes its first breath at birth.
Infants who have inhaled meconium may appear limp at birth, have a
bluish skin color, breath rapidly or with difficulty, or not
breathe at all. When meconium is inhaled, it can block the infants
airways either partially or completely. This can cause the air
sacs, called alveoli, that are supplied by the airways to
collapse, making breathing difficult.
Meconium can also irritate the lungs and lead to
inflammation and pneumonia. In severe cases, air is trapped in
areas that are supplied by the blocked airways and the lungs
become overinflated. Overinflated lungs can, in turn, cause lung
rupture and collapse, called pneumothorax. However, infants with
meconium aspiration rarely have permanent lung damage.
How is it diagnosed?
When a mother's water breaks before delivery, the doctors and/or
nurse always check the amniotic fluid for signs of the green
meconium stain. When amniotic fluid contains meconium, the fetus
is monitored for signs of distress during delivery. Upon birth,
the doctor can see meconium staining on the infant's vocal cords
using an instrument called a laryngoscope, and may hear crackling
sounds in the lungs by listening to the infant's chest with a
stethoscope. Other diagnostic tests include tests of blood oxygen
levels and chest x-ray.
What is the treatment?
The newborn's mouth, nose, and throat are suctioned immediately to
remove any meconium fluid. If there were signs of fetal distress,
meconium that has entered the baby's windpipe (trachea) is removed
through a tracheal tube, which suctions the lungs until there is
no meconium in the suctioned fluid. If the infant is showing signs
of respiratory distress, he or she is treated with oxygen. In
cases of severe aspiration, infants may need the help of a
ventilator, which is a mechanical device that forces air in and
out of the lungs through a tube passed through the nose or mouth
and into the trachea. Any infant with meconium aspiration is
observed carefully for signs of complications.
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