What describes the abdominal findings in congenital pyloric stenosis?

In cases of congenital pyloric stenosis, a firm epigastric mass is a characteristic finding during a physical examination. This mass is often described as an "olive-shaped" structure located in the right upper quadrant of the abdomen, which represents the hypertrophied pyloric muscle. This anatomical change causes obstruction at the pylorus, leading to projectile vomiting in infants and other associated symptoms.

The presence of a firm epigastric mass is particularly significant in diagnosing congenital pyloric stenosis, as it is a direct result of the muscle's thickening and narrowing of the pyloric channel, making it a key indicator of the condition.

While hyperactive bowel sounds can sometimes be present due to the increased peristalsis as the body attempts to compensate for the obstruction, they are not as definitive for diagnosing pyloric stenosis as the palpable mass. Asymmetrical abdominal swelling is more indicative of other conditions and does not typically present in pyloric stenosis. Rebound tenderness indicates irritation or inflammation often seen in appendicitis or peritonitis, which is not typically associated with pyloric stenosis. The firm epigastric mass is thus the most indicative finding in this specific condition.