Which symptom often signals a diagnosis of Hirschsprung's disease in infants?

Failure to pass meconium is a significant symptom that often indicates the diagnosis of Hirschsprung's disease in infants. This condition is characterized by the absence of ganglion cells in a segment of the bowel, leading to a lack of normal peristalsis in that area. As a result, affected infants may not have their first bowel movement, which typically occurs within the first 24 to 48 hours after birth. This failure to pass meconium can lead to abdominal distension and discomfort.

In contrast, the other symptoms presented, such as bloody diarrhea, frequent vomiting, and excessive crying, can be associated with a variety of gastrointestinal issues but are not specifically indicative of Hirschsprung's disease. While these symptoms may occur in infants with different gastrointestinal conditions, the hallmark sign of Hirschsprung's is specifically the inability to pass meconium within the expected timeframe, making it a crucial symptom for diagnosis.