Which one of the following is the most common cause of abdominal mass in neonates?
**Core Concept**
Cystic fibrosis is a genetic disorder that affects the secretory glands, leading to the production of thick, sticky mucus that can clog the airways and trap bacteria. However, in neonates, cystic fibrosis is often associated with gastrointestinal manifestations, including meconium ileus and intestinal obstruction. The most common cause of abdominal mass in neonates is related to gastrointestinal obstruction or malformation.
**Why the Correct Answer is Right**
Meconium ileus is a condition where the small intestine is obstructed by a thick meconium plug, often seen in infants with cystic fibrosis. The meconium plug can cause an abdominal mass due to the accumulation of meconium in the small intestine. This condition can lead to intestinal obstruction, which may require surgical intervention. The intestinal obstruction can cause an abdominal mass, which may be palpable on physical examination.
**Why Each Wrong Option is Incorrect**
**Option A:** Congenital hypertrophic pyloric stenosis is a condition characterized by thickening of the pyloric muscle, leading to gastric outlet obstruction. While it can cause an abdominal mass, it is more commonly seen in infants older than 3 weeks.
**Option B:** Intussusception is a condition where a part of the intestine telescopes into another part, leading to intestinal obstruction. It is a common cause of abdominal mass in infants, but it is not as common as meconium ileus in neonates.
**Option C:** Hirschsprung's disease is a congenital condition characterized by the absence of ganglion cells in the distal colon, leading to intestinal obstruction. While it can cause an abdominal mass, it is more commonly seen in infants older than 6 months.
**Clinical Pearl / High-Yield Fact**
Meconium ileus is a critical condition that requires prompt diagnosis and treatment to avoid complications such as intestinal perforation and peritonitis. A high index of suspicion is necessary to diagnose meconium ileus in neonates with abdominal mass or intestinal obstruction.
**Correct Answer: C. Hirschsprung's disease is not the most common cause of abdominal mass in neonates.