What finding would be observed in a patient with gastric retention?

In a patient with gastric retention, abdominal distention is a common finding due to the accumulation of food and fluids in the stomach that cannot be emptied effectively. This condition leads to an increase in the volume and pressure within the stomach, resulting in a noticeable swelling or bloating of the abdomen. The distention can also be accompanied by discomfort or pain as the distended stomach exerts pressure on surrounding structures.

The other potential findings, while they may occur due to various reasons, are not specifically indicative of gastric retention. For instance, increased appetite typically occurs in conditions where there is effective digestion and absorption, while a dry mouth might relate more to dehydration or certain medication side effects rather than retention. Back pain isn't a typical symptom of gastric retention directly but could relate to associated discomfort from abdominal distention. Thus, abdominal distention specifically aligns with the physical manifestation of gastric retention, making it the correct choice.