Which of the following conditions is NOT related to post-operative complications?

Chronic renal failure is not directly classified as a post-operative complication. While it can certainly be influenced by surgical procedures, particularly in patients with pre-existing renal conditions or those undergoing major surgeries, it does not arise specifically due to the operation itself. Post-operative complications typically develop as a direct result of surgical intervention.

In contrast, conditions like pneumonia, esophageal reflux, and subphrenic abscess are specific complications that can occur due to factors related to surgery. Pneumonia may arise due to atelectasis or decreased mobility post-surgery. Esophageal reflux can result from changes in position, manipulation of the diaphragm, or anesthetic effects. A subphrenic abscess can develop from infection after an abdominal procedure. Each of these conditions is a recognized complication that may result from surgical interventions, making them directly related to the post-operative period.