A pregnant woman at 37 weeks of gestation has had ruptured membranes for 26 hours. A cesarean section is performed for failure to progress. The fetal heart rate (FHR) before birth is 180 beats per minute with limited variability. At birth, the newborn has Apgar scores of 6 and 7 at 1 and 5 minutes and is noted to be pale and tachypneic. Based on the maternal history, what is the most likely cause of this newborn’s distress?
A. Hypoglycemia
B. Phrenic nerve injury
C. Sepsis
D. Meconium aspiration syndrome
The Correct Answer and Explanation is:
The most likely cause of the newborn’s distress in this scenario is D. Meconium aspiration syndrome (MAS).
Explanation:
In this case, the pregnant woman has experienced ruptured membranes for 26 hours, which increases the risk of meconium-stained amniotic fluid. The prolonged rupture can lead to fetal distress, indicated by the fetal heart rate (FHR) of 180 beats per minute with limited variability, suggesting fetal hypoxia or stress. The combination of these factors raises concern for the potential inhalation of meconium by the fetus.
At birth, the newborn exhibits an Apgar score of 6 at 1 minute, indicating some level of distress, which improved to 7 at 5 minutes, but the newborn is noted to be pale and tachypneic. The pallor and tachypnea are consistent with respiratory distress, which is a hallmark of MAS. When meconium is present in the amniotic fluid and the fetus inhales it during or just before birth, it can cause obstruction in the airways and lead to chemical irritation, resulting in respiratory distress.
While other options like hypoglycemia (A), phrenic nerve injury (B), or sepsis (C) could cause some level of distress in a newborn, they do not align as closely with the maternal history and the symptoms observed at birth. Hypoglycemia typically presents with jitteriness or lethargy, not primarily respiratory symptoms. Phrenic nerve injury would cause respiratory distress but would be more localized and not associated with the described fetal monitoring findings. Sepsis is a possibility, but the immediate presentation of respiratory distress and the context of meconium exposure make MAS the most probable cause in this scenario.
In summary, the combination of prolonged ruptured membranes, fetal heart rate changes, and the clinical presentation of the newborn strongly indicates meconium aspiration syndrome as the underlying cause of the newborn’s distress.