Meconium aspiration syndrome

Other Names: MAS 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. This can cause breathing difficulties due to swelling (inflammation) in the baby's lungs after birth.

Release of meconium into the amniotic cavity and then intrauterine gasping of post-term neonates may cause meconium aspiration syndrome.

Cause

Meconium is the term used for the early feces passed by a newborn soon after birth. In some cases, the baby passes the meconium while still inside the uterus. This most often happens when babies are under stress because they are not getting enough blood and oxygen. Once the meconium has passed into the surrounding amniotic fluid, the baby may breathe meconium into the lungs. This may happen while the baby is still in the uterus or immediately following birth.

Riskfactors

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

Signs and symptoms

Most babies who have passed meconium into the amniotic fluid do not breathe it into their lungs during labor and delivery. They are unlikely to have any symptoms or problems.

Babies who do breathe in this fluid may have the following:

• Bluish skin color (cyanosis) in the infant
• Working hard to breathe (noisy breathing, grunting, using extra muscles to breathe, breathing rapidly)
• No breathing (lack of respiratory effort, or apnea)
• Limpness at birth

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 30%-79% of people have these symptoms

• Abnormal heart rate variability
• Caesarian section
• Fetal distress
• Postterm pregnancy
• Respiratory distress(Breathing difficulties)
• Transient pulmonary infiltrates

5%-29% of people have these symptoms

• Aspiration pneumonia
• Atelectasis(Partial or complete collapse of part or entire lung)
• Hypoxemia(Low blood oxygen level)
• Intrauterine growth retardation(Prenatal growth deficiency)
• Maternal diabetes(gestational diabetes)
• Maternal hypertension
• Meconium stained amniotic fluid
• Neonatal asphyxia
• Pneumomediastinum
• Pneumothorax(Collapsed lung)
• Premature rupture of membranes
• Pulmonary arterial hypertension(Increased blood pressure in blood vessels of lungs)
• Wheezing

1%-4% of people have these symptoms

• Encephalopathy
• Pulmonary insufficiency

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

A special care team should be present when the baby is born if traces of meconium are found in the amniotic fluid. This happens in more than 10% of normal pregnancies. If the baby is active and crying, no treatment is needed.

If the baby is not active and crying right after delivery, the team will:

• Warm and maintain normal temperature
• Dry and stimulate the baby
• This intervention is often all babies need to begin breathing on their own.

If the baby is not breathing or has a low heart rate:

• The team will help the baby breathe using a face mask attached to a bag that delivers an oxygen mixture to inflate the baby's lungs.
• The infant may be placed in the special care nursery or newborn intensive care unit in order to be watched closely.

Other treatments may include:

• Antibiotics to treat possible infection.
• Breathing machine (ventilator) if baby is unable to breathe on their own or needs a large amount of extra oxygen.
• Oxygen to keep blood levels normal.
• Intravenous (IV) nutrition -- nutrition through the veins -- if breathing problems are keeping baby from being able to feed by mouth.
• Radiant warmer to maintain body temperature.
• Surfactant to help lungs exchange oxygen. This is only used in more severe cases.
• Nitric oxide (also referred to as NO, an inhaled gas) to help blood flow and oxygen exchange in the lungs. This is only used in severe cases.
• ECMO (extracorporeal membrane oxygenation) is a kind of heart/lung bypass. It may be used in very severe cases.

NIH genetic and rare disease info

• NIH info on Meconium aspiration syndrome

Meconium aspiration syndrome is a rare disease.

Meconium aspiration syndrome Resources
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