Meconium Aspiration Syndrome

Meconium aspiration syndrome is a breathing difficulty occurring in newborns due to the aspiration of meconium present in the amniotic fluid at the time of birth or prior to it. It is characterized by severe respiratory distress in the infant.

  • Fetal distress and oxygen insufficiency are the usual reasons causing the fetus to pass the fecal matter meconium while they are still in the womb.
  • The fetus may gasp as a reflex reaction to reduced oxygen supply in the womb, resulting in the inhalation of meconium along with the amniotic fluid into the lungs.
  • Meconium aspiration syndrome typically displays the symptoms of respiratory distress such as bluish discoloration of the skin, and labored or rapid breathing with a grunting sound during exhalation.
  • Presence of meconium in the amniotic fluid detected at the time of delivery, combined with breathing difficulty in the newborn, leads to the diagnosis of meconium aspiration syndrome. A chest x-ray may help confirm the diagnosis.
  • Oxygen is immediately administered to the infant displaying meconium aspiration syndrome, but additional respiratory assistance or even ventilator support may be necessary.
  • If given immediate medical care, infants with meconium aspiration syndrome may recover, but in severe cases, the condition may become fatal.

The intestine of the fetus is filled with a greenish black sticky substance called meconium. After the infant is born, the meconium is normally passed in the first few bowel movements as the infant begins to feed. However, in certain situations, the fetus passes the meconium within the womb, causing it to be mixed with the amniotic fluid. Fetal distress, usually resulting from inadequate oxygen supply to the fetus via the placenta, is the most common cause of meconium being passed within the womb. The distressed fetus tends to gasp reflexively, resulting in the aspiration of the meconium-tainted amniotic fluid into its lungs.

When the infant is born and it tries to breathe in air, the aspirated meconium may cause blockages in the airway. It may result in the collapse of some areas of the lungs. When partial blocks occur in the airway, the air reaches the lungs during inhalation but it is not expelled on exhalation. When this is repeated, that part of the lung may get overfilled, causing the air sacs to over-expand. Eventually, the overstretched tissue becomes weak, leading to rupture as well as collapse of the infant’s lung. It results in a condition called pneumothorax in which the air fills the chest cavity or thorax around the collapsed lung.

Pneumonitis or severe lung inflammation may be caused by the aspiration of meconium into the lungs. There is a very high risk of developing lung infections too. Persistent pulmonary hypertension is a very serious, and often fatal, condition that has a higher chance of occurring in infants with meconium aspiration syndrome.

The severity of meconium aspiration syndrome depends on the amount of the substance inhaled by the fetus. Postmature infants are often severely affected as they inhale larger amounts of the substance. This happens because the reduced quantity of amniotic fluid towards the end of gestation results in a higher concentration of meconium in the fluid which is aspirated by the fetus.

Symptoms and Diagnosis

Typical symptoms of respiratory distress such as rapid breathing, and grunting sound while exhaling, are displayed by infants who have meconium aspiration syndrome. Breathing is labored and every time a breath is taken, the chest below the breastbone is drawn deep in. Cyanosis or bluish discoloration to the skin, typically indicating low oxygen levels in the blood, may be present. The baby may have low blood pressure too.

When meconium is detected in the amniotic fluid when the baby is being delivered, and if the infant is showing signs of respiratory distress, meconium aspiration syndrome is diagnosed. A chest x-ray can confirm the condition.


When meconium is present in the amniotic fluid at the time of delivery, it indicates the possibility of meconium aspiration. Often the infant may not be breathing and the limp body may be coated with meconium. The nose and mouth of the baby are cleaned immediately and the substance is sucked out from the throat. A suction tube is introduced into the windpipe also, to remove the meconium that may have been aspirated by the infant. This procedure may have to be repeated several times to clear the trachea of all the meconium.

Antibiotic treatment is given to the infant to prevent possible infections. Oxygen is administered to the baby to help with breathing, and if required, ventilator support is also given. The baby is closely monitored for any complications like pneumothorax developing. Pulmonary hypertension is another potentially fatal complication to watch out for in babies who have aspirated meconium.

With immediate medical intervention and adequate treatment, babies who develop meconium aspiration syndrome have a very good chance of recovery. But in some cases, the various complications which develop, especially persistent pulmonary hypertension, may result in a fatal outcome.

Watch This Video About Meconium Aspiration Syndrome:

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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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