Meconium Aspiration Syndrome (MAS)
Meconium aspiration syndrome (MAS) is respiratory distress in a newborn baby caused by the presence of meconium in the tracheobronchial airways.
Meconium is a dark green fecal material produced in the intestines of a fetus before birth. After delivery, your newborn will pass meconium stools for the first few days of life. Stress that your baby experiences before or during birth may cause your baby to pass meconium stool while still in the uterus. The meconium stool then mixes with the amniotic fluid that surrounds the fetus.
Meconium Aspiration Syndrome (MAS) is a leading cause of severe illness and death in the newborn, occurs in about 5 percent to 10 percent of births. It typically occurs when the fetus is stressed during labor, especially when the infant is past its due date.
Symptoms –
• Bluish skin color
• Rapid breathing
• Dark, greenish staining or streaking of the amniotic fluid or the obvious presence of meconium in the amniotic fluid
• Limpness in infant at birth
• Muscles of the ribs pulling in toward the chest when the child breathes
• Grunting sounds with breathing
• An enlarged or bloated chest because of trapped air
Causes –
Healthcare providers don’t fully understand why babies release stool before they are born. It may be a natural event or it may be caused by stress. Stress often results when the amount of oxygen available to the fetus is reduced. Common causes of fetal stress include:
• a pregnancy that goes past the due date (more than 40 weeks)
• difficult or long labor
• certain health issues experienced by the mother, including hypertension (high blood pressure) or diabetes
• an infection
The fetus doesn’t begin to produce meconium until later in pregnancy, so as a pregnancy goes past its due date, the fetus has the potential to be exposed to meconium for a longer period of time.
As pregnancy progresses to term and beyond, the amount of amniotic fluid is also decreased, which concentrates the meconium. As a result, MAS is more common in overdue newborns as compared to term newborns. Meconium aspiration syndrome (MAS)is rare in preterm newborns.
Risk Factors –
Risk factors that may cause stress on the baby before birth include:
• “Aging” of the placenta if the pregnancy goes far past the due date
• Decreased oxygen to the infant while in the uterus
• Diabetes in the pregnant mother
• Difficult delivery or long labor
• High blood pressure in the pregnant mother
Complications –
Most newborns with meconium aspiration syndrome (MAS)won’t have any long-term health complications. However, MAS is a serious issue that can have an immediate impact on your newborn’s health. Meconium in the lungs can cause inflammation and infection.
Meconium can also block the airways, which can cause lung over expansion. If a lung over expands or inflates too much, it can rupture or collapse. Then air from inside the lung can accumulate in the chest cavity and around the lung. This condition, known as a pneumothorax, makes it difficult to reinflate the lung.
MAS increases the risk of your infant developing persistent pulmonary hypertension of the newborn (PPHN). High blood pressure in the vessels of the lungs restricts blood flow and makes it difficult for your baby to breathe properly. PPHN is a rare but life-threatening condition.
On rare occasions, severe MAS may limit oxygen to the brain. This may cause permanent brain damage.
Diagnosis –
Before birth, the fetal monitor may show a slow heart rate. During delivery or at birth, meconium can be seen in the amniotic fluid and on the infant.
The infant may need help with breathing or heartbeat right after birth. They may have a low Apgar score.
The health care team will listen to the infant’s chest with a stethoscope. This may reveal abnormal breath sounds, especially coarse, crackly sounds.
A blood gas analysis will show:
• Low (acidic) blood pH
• Decreased oxygen
• Increased carbon dioxide
A chest x-ray may show patchy or streaky areas in the infant’s lungs.
Treatment –
Early detection is key. A fetal monitor can detect if your baby is experiencing stress. If your doctor thinks your baby may have inhaled meconium, a special care team should be present during delivery. If after the baby is born, he’s active and crying, no treatment is necessary.
However, if the baby has trouble breathing, the doctor will quickly need to clear away as much meconium as possible to decrease the amount of meconium the baby inhales. He’ll suction the mouth, nose, and throat. Then he’ll insert a tube called a laryngoscope down the baby’s throat and into the trachea to remove any meconium there.
If your baby is not breathing or has a low heart rate, a facemask with oxygen can help inflate the baby’s lungs and help him or her breathe. Your baby may need to be monitored closely in a newborn intensive care unit (NICU). In the NICU, he or she may get:
• Oxygen therapy.
• Antibiotics to treat infection.
• Surfactant (a substance that helps the lungs expand properly).
• A radiant warmer to control his temperature.
• Frequent blood tests to see if he’s getting enough oxygen.
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