Potential for recovery in bladder function after removing a urethral obstruction

We examined the relation between the loss of bladder function during obstruction and the potential for recovery of function after de-obstruction.

Guinea pigs received a partial urethral obstruction. Bladder pressure, urine flow rate, detrusor overactivity (DO), compliance and contractility were examined weekly for 2-4 weeks (short), 6-8 weeks (medium), or 9-12 weeks (long). Then the obstruction was removed and bladder function followed up to 7 weeks. The groups were compared to animals receiving only obstruction or a sham operation.

During obstruction the three de-obstruction groups and the obstruction group progressively lost bladder function. Flow rate remained stable, compliance decreased, pressure, contractility and DO increased. After de-obstruction the response in the three de-obstruction groups varied. In S, bladder pressure and compliance normalized, contractility initially increased then decreased towards high normal values, DO remained high normal and flow rate increased. In M, bladder pressure and DO decreased to above average normal levels. Compliance improved but did not normalize. Contractility initially stabilized, then decreased to just above the normal range. Flow-rate increased. In L, bladder pressure and DO decreased to high normal. Compliance did not improve. Contractility decreased directly after de-obstruction, stabilizing at an above normal level, flow-rate increased.

The potential for functional recovery decreases with increasing loss of bladder function. At all stages of bladder dysfunction, voiding pressure appears to normalize after de-obstruction. However, contractility remains high and compliance low. Such a bladder may be more vulnerable to new events of outflow obstruction than a low contractile, normal compliant bladder.