Which clinical finding supports the diagnosis of congenital diaphragmatic hernia (CDH) in an infant?

The clinical finding that most strongly supports the diagnosis of congenital diaphragmatic hernia (CDH) in an infant is the auscultation of bowel sounds over the chest cavity. In CDH, the diaphragm fails to fully develop, allowing abdominal organs, such as the stomach and intestines, to move into the thoracic cavity. This displacement can lead to auscultation of bowel sounds in the chest region, which is an unusual finding and indicative of the condition.

Diminished breath sounds on the affected side can occur as well since lung development may be impaired due to space limitations from the herniated organs. However, it is the abnormal sounds of bowel in the thoracic cavity that more definitively indicate the presence of CDH.

The presence of bowel sounds over the abdomen alone does not suggest a hernia; rather, it is the location of those sounds that highlights the abnormal positioning of gastrointestinal organs. Abdominal distension can accompany various conditions affecting the infant, but it is not specific to CDH.