SPINAL CORD INJURY AND BLADDER FUNCTION

• In spinal cord injury, bladder sphincter relaxation is absent, leading to urinary retention.

• As soon as hourly urine output is no longer necessary, the indwelling bladder catheter should be removed to reduce the risk of urinary tract infections (a life-threatening complication of acute spinal cord injury).

• Intermittent catheterization decreases the risk for urinary tract infections.

Considerations

Immediately following acute spinal cord injury, spinal shock develops.  Spinal shock is characterized by:

• Flaccid paralysis (loss of bladder tone) below the level of the injury, and loss of spinal cord
  reflexes including bladder and bowel sphincter control. 

• Spinal shock often coincides with neurogenic shock, which is evidenced by loss of autonomic control (bradycardia, vasodilation,
  hypotension). 

• Spinal shock can persist for several weeks, and is associated with an inability to retain urine or bowel contents.    Although urinary incontinence may be present, bladder emptying is also dysfunctional, making some form of catheterization mandatory. 

• When spinal shock ends, spinal reflexes begin to return.  Bulbocavernal, bladder and rectal Sphincter reflex are amont the first responses to appear and are generally signs that the spinal shock phase is ending.  The ability to retain urine is restored, and spastic movements of the paralyzed limbs may appear (care should be taken not to mistake these involuntary movements for a return of voluntary movement). 

• Although bladder and bowel sphincter tone may allow the paralyzed individual to maintain continence of urine and feces, the cord injury prevents the individual from contracting the bladder and relaxing the sphincters to facilitate elimination. 

• Retained urine or feces is the most common cause of autonomic dysreflexia. Autonomic dysreflexia is a life threatening complication that is most common in patients with injuries above T6.  This is can occur as a result of any noxious stimulous AFTER the period of spinal shock ends. Patients who develop autonomic dysreflexia are at risk for the rest of their lives.

• Then hourly urine output is no longer needed, diuretic use has stopped and urine output stabilizes,  routine intermittent catheterization can be considered. Catheterization should be performed q 4 h initially.  The volume of urine with each catheterization should be less than 500 mL. Larger volumes can precipitate bladder spasm, autonomic dysreflexia, renal reflux and overflow incontinence. 

• The goal for intermittent catheterization is a stable intake of ~2Litres per day and intermittent cathetrization Q 6 H with an output of less than or equal to 500 mL. 

• Fluid restriction shoudl be avoided as it increases the risk for urinary tract infection, renal calculi and hypotension during mobilizaiton.

• Intermittent catheterization frequency is required for patient with spinal cord injury and intermittent catheterization who require diuretics. Indwelling catheterization may be more appropriate if diuretic use is required. 

• Following catheter removal, incomplete bladder sphincter control may cause some urinary incontinence.  Condom drainage can be used to protect skin and linen, however, it is important to continue to perform intermittent catheterization, as complete bladder emptying does not usually occur.