What is the typical outcome of chronic functional urethral obstruction if untreated?

Chronic functional urethral obstruction, if left untreated, typically leads to progressive bladder dysfunction and can ultimately result in renal failure. The prolonged obstruction causes the bladder to work excessively hard to expel urine against the resistance presented by the obstructed urethra. Over time, this can lead to increased bladder wall thickness, decreased bladder compliance, and potentially, bladder muscle damage. As bladder function deteriorates, the kidneys can begin to suffer from the resultant back pressure, leading to conditions such as hydronephrosis or renal impairment. Therefore, monitoring and intervention in cases of urethral obstruction are crucial to prevent these serious complications.