Meconium aspiration occurs when a baby breathes in amniotic fluid containing meconium (the baby's first stools).
Before or during labor, the fetus sometimes passes the meconium stool into the amniotic fluid. It is not clearly understood why this happens. It may be a natural event, but it is also thought to be related to fetal distress in some babies. When the thick meconium mixes into the amniotic fluid, it is swallowed and breathed into the airways of the fetus. As the baby takes the first breaths at delivery, meconium particles enter the airways and can be aspirated (inhaled) deep into the lungs.
Meconium is passed into the amniotic fluid in about 5 to 15 percent of births. It usually occurs in babies born at term (37 to 41 weeks) or post-term (after 42 weeks).
Meconium particles in the amniotic fluid can block small airways and prevent the exchange of oxygen and carbon dioxide after birth. Some babies have immediate respiratory distress and have to be resuscitated at birth. Others develop respiratory distress within a few hours.
Some babies with meconium aspiration need a mechanical ventilator (breathing machine) because of the difficulty breathing. The plugged airways may cause air to be trapped and leak into the tissues in and around the lungs. Infection can also occur causing pneumonia. Although the condition often improves within a few days, severe meconium aspiration, and the respiratory problems it causes, may lead to death in a small number of babies.
Meconium in the amniotic fluid gives the fluid a greenish color. This is called meconium staining. Babies who have been exposed to meconium in the amniotic fluid for a long time may have yellowed skin and nails.
The following are the most common symptoms of meconium aspiration. However, each baby may experience symptoms differently. Symptoms may include:
- rapid breathing
- retractions (pulling in of the chest wall)
- grunting sounds with breathing
- cyanosis (blue coloring)
- overdistended chest
The symptoms of meconium aspiration may resemble other conditions or medical problems. Always consult your baby's physician for a diagnosis.
The presence of meconium in the amniotic fluid is key to the diagnosis. A chest x-ray also helps diagnose meconium aspiration. X-rays are a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
Specific treatment for meconium aspiration will be determined by your child's physician based on the following:
- the amount and thickness of the meconium
- the length of time the baby was exposed
- the degree of respiratory distress
At delivery, treatment may include:
- suctioning of the upper airways (nose, mouth, and throat)
- suctioning of the lower airways through an endotracheal tube (ET) placed in the windpipe
- supplemental oxygen given by face mask or mechanical ventilator
Early identification of meconium aspiration is essential to preventing severe aspiration problems. A technique called amnioinfusion is sometimes used during labor with meconium-stained amniotic fluid. This procedure uses a small tube inserted into the uterus through the vagina. Sterile fluid is infused through the tube to help dilute the thick meconium. Suctioning of the upper airways as soon as a baby's head is delivered may also help reduce the effects of meconium aspiration.
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