Which one of the following is the most common cause of abdominal mass in neonates –
**Core Concept**
The question is testing the knowledge of a common congenital anomaly that presents as an abdominal mass in neonates. This condition is a result of intestinal obstruction and is often associated with polyhydramnios in utero.
**Why the Correct Answer is Right**
The correct answer is **C. Intestinal Atresia**. Intestinal atresia is a congenital defect characterized by the complete or partial obstruction of the small intestine. This occurs due to the failure of recanalization of the intestinal lumen during embryonic development. The most common location for intestinal atresia is the duodenum, which can lead to abdominal distension and a palpable mass in the newborn period. The condition often presents with bilious vomiting, abdominal distension, and failure to pass meconium within the first 48 hours of life.
**Why Each Wrong Option is Incorrect**
* **Option A:** Omphalocele is a congenital anomaly where the abdominal contents herniate through the umbilical ring. While it can present as an abdominal mass, it is not the most common cause.
* **Option B:** Gastroschisis is a congenital defect characterized by a small defect in the anterior abdominal wall, usually to the right of the umbilicus. This can also present as an abdominal mass, but it is less common than intestinal atresia.
* **Option D:** Meconium ileus is a condition associated with cystic fibrosis where the meconium is thick and sticky, causing intestinal obstruction. While it can present with abdominal distension, it is not the most common cause of abdominal mass in neonates.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that intestinal atresia often presents with bilious vomiting, which is a sign of intestinal obstruction. This is in contrast to gastric obstruction, which typically presents with non-bilious vomiting.
**Correct Answer:** C. Intestinal Atresia