What physical finding indicates pyloric stenosis in a 2-month-old during examination?

The presence of a hard, moveable "olive-like mass" in the upper right quadrant is a classic physical finding indicative of pyloric stenosis in infants. Pyloric stenosis occurs when the pylorus, the opening from the stomach into the small intestine, becomes narrowed due to muscle hypertrophy. This narrowing leads to obstruction, resulting in projectile vomiting and difficulty with food passing from the stomach.

During a physical examination, the "olive-like mass" can often be felt in the abdomen and represents the enlarged pyloric muscle. This finding is critical for diagnosis, especially in young infants who display symptoms such as projectile vomiting and signs of dehydration. Observing this mass provides strong evidence supporting the diagnosis of pyloric stenosis, prompting further evaluation and management.

In contrast, other options like severe diarrhea, constant vomiting after feeding, or a rash on the abdomen do not specifically point to pyloric stenosis. While vomiting is a symptom of the condition, it is the distinct abdominal mass that is the hallmark sign that helps confirm the diagnosis during a physical examination.