How does cystic fibrosis present in comparison to Hirschsprung disease regarding meconium passage?

Cystic fibrosis is characterized by the production of thick, sticky mucus due to mutations in the CFTR gene, which affects various organs, particularly the lungs and the pancreas. In newborns with cystic fibrosis, this thick mucus can lead to meconium ileus, a condition where the meconium—the first stool a newborn passes—is abnormally thick and viscous. This can result in a blockage in the intestines, preventing normal passage of meconium and leading to signs of bowel obstruction.

In contrast, Hirschsprung disease is a congenital condition characterized by the absence of ganglion cells in a segment of the colon, which results in an inability to properly move stools through that segment. In this condition, meconium passage can be delayed because the affected segment is unable to propel the meconium forward, but typically the initial passage might be normal or delayed without the characteristic thick obstruction seen in cystic fibrosis.

Therefore, the correct answer emphasizes that in cystic fibrosis, the newborn presents with thick, inspissated meconium causing obstruction, distinguishing it from other conditions like Hirschsprung, where the issue arises from a lack of motility secondary to the absence of neural ganglia, rather than thick meconium itself