Which sign is indicative of a gastrointestinal obstruction in a term infant?

Bilious emesis, which refers to vomiting that contains bile, is a significant clinical sign suggestive of a gastrointestinal obstruction in a term infant. This occurs because when there is an obstruction in the gastrointestinal tract, the normal flow of bile is disrupted. As a result, bile can back up and be expelled through vomiting. Specific patterns of vomiting can provide valuable diagnostic information; for instance, if the vomit is yellow-green and bilious, it suggests that the obstruction is distal to the duodenum where bile enters the gastrointestinal tract.

The other signs, while they may be associated with gastrointestinal issues, do not specifically indicate an obstruction. For example, abdominal distension can be due to a variety of causes, including feeding intolerance or gas buildup, rather than a direct obstruction. Constipation is not typically seen in the context of an obstruction, as this condition may imply that stool is retained rather than obstructed. Finally, failure to thrive indicates an overall lack of adequate nutrition and growth, which could stem from multiple underlying issues but does not specifically point to an obstructive process in the gastrointestinal tract. Therefore, bilious emesis stands out as the key sign of potential gastrointestinal obstruction in a term infant, warranting immediate evaluation and intervention.