Meconium aspiration syndrome Health Article

Definition

Meconium is the first feces (stool) of the newborn. Meconium aspiration syndrome is a serious condition in which a newborn breathes a mixture of meconium and amniotic fluid into the lungs around the time of delivery.

Alternative Names

MAS

Causes, incidence, and risk factors

Meconium aspiration syndrome is a leading cause of severe illness and death in the newborn. The possibility of inhaling meconium occurs in about 5-10% of births. It typically occurs when the fetus is stressed during labor, especially when the infant is past its due date.

Stress during labor can cause increased movement of the infant's intestines and relaxation of the anal sphincter, causing meconium to pass into the surrounding amniotic fluid. If the infant breathes while still in the uterus or while still covered by this fluid after birth, the mixture can enter the lungs and partially or completely block the infant's airways.

Risk factors include:

• Fetal distress
• Decreased oxygen to the infant while in the uterus
• Diabetes in the pregnant mother
• Difficult delivery
• High blood pressure in the pregnant mother

Symptoms

• Bluish skin color in the infant
• Breathing problems
  • Difficulty breathing (the infant needs to work hard to breathe)
  • No breathing
  • 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
• Greenish-stained skin in infant (occurs if meconium passed a long period before delivery)
• Skin peeling
• Weight loss

Signs and tests

Before birth, the fetal monitor may show a slow heart rate. At birth, meconium can be seen in the amniotic fluid. The infant may have a low Apgar score.

The most accurate test to check for possible meconium aspiration involves looking for meconium staining on the vocal cords. This is done in the delivery room using a device called a laryngoscope.

The health care team will listening to the infant's chest with a stethoscope and may hear abnormal breath sounds, especially coarse, crackly sounds.

A blood gas analysis shows low blood acidity, decreased oxygen, and increased carbon dioxide.

A chest x-ray may show patchy or streaky areas on lungs.