Alternative Names meconium aspiration syndrome (MAS)
Definition Before birth, a baby may breathe in amniotic fluid, which is the fluid surrounding the baby in the uterus, and meconium, a thick, sticky, greenish substance found in the foetal intestines. This is called meconium aspiration and it can lead to serious health problems.
What is going on in the body? Even though meconium strained liquor is reported in up to 12% of births only a small proportion of these result in the newborn infant aspirating meconium into its lungs. Aspiration occurs mostly because of asphyxia. Aspiration doesn't occur with normal foetal breathing movements. If asphyxia occurs resulting in aspiration then the meconium can partly or completely block the airways, which keeps the baby from getting enough oxygen. This can lead to severe illness and even death among newborns.
What are the signs and symptoms of the condition? Meconium in the amniotic fluid does not cause problems for every newborn. In some babies, though, it is the first step toward meconium aspiration syndrome (MAS). Babies who have this may:
have thick, greenish amniotic fluid in the mouth and pharynx, or the back portion of the throat that must be suctioned at birth.
have poor muscle tone.
have bluish skin colour at birth.
have a poor rating on the APGAR test, which measures colour, respiration, activity, cry and muscle tone in the newborn.
have trouble breathing normally.
not be breathing.
have peeling skin, little fat under the skin and other signs that a pregnancy has gone on too long.
What are the causes and risks of the condition? Meconium in the amniotic fluid occurs more often when:
the foetus has not been growing properly, which is known as intrauterine growth retardation.
a pregnancy goes on for 42 weeks or longer.
something happens during labour to cause foetal distress.
the foetus is heavier than 9 pounds.
the umbilical cord is wrapped around the foetus's neck during labour.
What can be done to prevent the condition?
If at all possible, a baby should be born before the pregnancy reaches 42 weeks.
Any baby who is 42 weeks or older when born or may have suffered foetal distress during labour, should be watched closely after birth for signs of MAS.
If a woman's water breaks at home, she should tell her doctor the colour of the fluid.
When green-tinged amniotic fluid is reported or seen, labour should be monitored closely.
When the baby's head emerges during the birth, the midwife or doctor should suction out as much meconium as possible from the mouth, nose and airways.
How is the condition diagnosed? Foetal monitoring during labour may help diagnose a problem. A slowed heart rate suggests severe foetal distress that may call for an immediate delivery. At birth, the baby may:
have low APGAR scores.
be floppy or bluish with laboured or no breathing.
have coarse, crackly lung sounds.
have abnormal blood gases, which are measures of oxygenation in the blood and level of acidity in the blood
have patchy streaks on the lungs in a chest X-ray
What are the long-term effects of the condition? What happens after a foetus inhales meconium depends on how much brain damage occurs due to a lack of oxygen. If the problem started in the mother's womb before labour began, it is likely to be worse than if it occurred late in labour. Other possible complications are:
What are the treatments for the condition? Meconium should be vigorously suctioned from the mouth and the nose before the baby's shoulders emerge from the birth canal. As soon as the baby is born, the labour room staff should put a tube down the baby's windpipe to see if any meconium has gone beyond the vocal cords. If so, it may go further into the lungs with the baby's first breath. Any meconium above or below the vocal cords should be suctioned out quickly. The baby may need to be given oxygen and be put in a respirator. Tapping the chest to loosen up thick secretions may help, too.
If an infection is suspected, the baby may be given preventive antibiotics.
What happens after treatment for the condition? After birth, the baby should be watched closely for any signs of trouble breathing or not getting enough oxygen. This may be done in a special care nursery.
If pneumonia sets in, the baby may need antibiotics for several weeks.
Should cerebral hypoxia, of lack of oxygen to the brain occur, seizures, dangerously low sodium levels, kidney failure and lasting damage to the nervous system may follow.
How is the condition monitored? Most babies with meconium aspiration syndrome recover. Their survival depends in part on how much, and for how long, their oxygen supply was affected.
Author: Eva Martin, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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