What is a common symptom of a subphrenic abscess?

A subphrenic abscess typically presents with fever and upper quadrant abdominal pain due to its location beneath the diaphragm. This condition often arises following abdominal surgery, perforation, or inflammation of adjacent organs, which can lead to infection and the accumulation of pus. The proximity of the abscess to the diaphragm can irritate the diaphragm and surrounding structures, resulting in referred pain that is commonly felt in the upper abdomen. Additionally, the systemic response to infection can cause fever. Therefore, the combination of fever and upper quadrant abdominal pain is a classic manifestation of a subphrenic abscess, making it the most relevant symptom in this context.