What is the main characteristic of post-renal (obstructive) acute renal failure?

The primary characteristic of post-renal (obstructive) acute renal failure is that the kidneys are functioning normally, but there is an obstruction that hampers the flow of urine. This obstruction can occur anywhere in the urinary tract, such as in the ureters, bladder, or urethra, preventing urine from being excreted effectively.

When obstruction occurs, the kidneys may still be producing urine, but the buildup of urine can lead to increased pressure within the renal system, ultimately causing damage if not resolved. This distinguishes post-renal failure from other types of renal failure where kidney function itself may be diminished or damaged directly.

Understanding this mechanism is crucial for diagnosing and managing patients with acute renal failure, as the approach to treatment can significantly differ depending on whether the issue is pre-renal, renal, or post-renal in origin.