MECONIUM ASPIRATION

Definition: When the newborn or fetus inhales meconium (first stool) into the lower

respiratory tract.

1. What caused this condition?

The baby had a bowel movement while still inside the mother’s uterus. Meconium is the name for the first stools that a baby passes. The meconium gets into the fluid surrounding the baby and can be swallowed into the lungs or breathing passageways prior to or at the time of birth. Babies that are under stress or go beyond their expected due date have a higher incidence of passing meconium while still in the uterus. Generally, meconium aspiration is seen in babies that are not premature.

2. Is this condition dangerous, and what kind of damage can it cause?

If the meconium gets into the airways leading to the lungs, it causes a blockage of the passageways. This stops or impedes the flow of air into and out of portions of the lungs. This can lead to low oxygen levels or a buildup of carbon dioxide.

     If significant, this disruption in the functioning of the lungs can lead to a continued high blood pressure in the blood vessels leading to the lungs. When this occurs, there is further inability of the lungs to get oxygen into the bloodstream and to remove carbon dioxide due to blood bypassing the lungs.

     Another common complication of meconium aspiration is the development of a hole in the lung(s). This is called a pneumothorax. Air escapes from the lung into the chest cavity and is trapped between the chest wall and lung. As the air builds up, it compresses the lung and again disrupts normal lung function.

3. What tests are needed to further define the condition?

The presence of meconium is noted when the water is broken either naturally or by the obstetrician. The fluid will have a greenish discoloration. The thickness and degree of discoloration indicates the amount of meconium present. After the baby is born chest X rays will confirm the findings of meconium aspiration if present. A sample of blood called a blood gas along with oxygen-level monitoring (pulse oximeter) will show low oxygen levels and disturbances in lung functioning.

4. What is the treatment?

Prevention is the main treatment. If meconium stained fluid is noted, the obstetrician may infuse sterile salt water into the uterus to dilute the meconium. At the time of delivery, the obstetrician will attempt to clean out the nose and mouth prior to the delivery of the rest of the baby. The baby may then have a breathing tube passed into the trachea, the main passage to the lungs, and suction applied while it is removed.

     If the baby has further or continued problems, then additional oxygen and/or a breathing machine may be needed. If a breathing tube is needed, the instillation of a medication called surfactant may be given through it to help break up the meconium and improve the function of the lungs. If the baby has significant breathing concerns, a ventilator called an oscillator may be used.

     If the baby develops a pneumothorax, or hole in the lung(s), a drainage tube may be needed. This drainage tube is called a chest tube, and it is placed between the ribs on the side of the air leak to prevent the lung from collapsing.

5. What side effects can occur from the treatment?

The most common early side effect is a hole in the lung(s) from air being trapped by the meconium or from the degree of ventilator support required to get acceptable oxygen and carbon dioxide levels. It is treated as mentioned above.

     The lungs can be injured from being on the ventilator. They may develop an inflammatory reaction to the irritation of the meconium and being on the ventilator and high oxygen concentrations. If this occurs, it may delay coming off of the ventilator and additional oxygen. This inflammatory response can occasionally lead to the baby having feeding problems due to increased work of breathing and needing extra oxygen at the time of discharge.

     Infrequently, a baby may have severe meconium aspiration along with severe elevations in the blood pressure in the blood vessels leading to the lungs. This may require treatment with a heart-lung bypass (ECMO).

6. How long will it take for my baby to show improvement?

Most babies get better in seven to ten days. A baby with severe meconium aspiration may require a longer hospital stay, potentially up to a month, to be well enough to be discharged.

7. What complications can develop?

The more frequent complications are the same as the side effects from being treated. Holes in the lung (pneumothoraces) or the failure of the blood pressure to lower in the lungs after birth (pulmonary hyper- tension) may be present and complicate the meconium aspiration. Occasionally, babies may have some inflammation in their lungs that delays their improvement.

8. Can pneumonia develop?

Pneumonia caused by bacteria is not associated with the meconium aspiration itself. Infection may occur in any patient that has a breathing tube in place and receives ventilatory support for a period of time, especially longer than fourteen days.

9. Will this condition weaken my baby’s lungs for the future?

Both the presence of meconium and being on a breathing machine with exposure to high concentrations of oxygen can cause an inflammatory response in the lungs. In some cases this can lead to delayed recovery and some lung abnormalities for the first several months of life. Most babies with mild-to-moderate meconium aspiration will not have any long-lasting lung problems.

10. After discharge from the hospital, what kind of follow-up will be needed?

In most cases, your child’s pediatrician will be all that is necessary. In severe cases of meconium aspiration, the baby may be at more risk for developmental delays and a developmental specialist may be required. 

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