Neurogenic Bladder and UTI

1. Pathophysiologic mechanism of UTI in neurogenic bladder

  • The high incidence of UTI after a SCI is due to abnormal emptying of the bladder and probably an impairment in the bladder defense mechanism against bacterial invasion and attachment to the bladder mucosa
  • Impairment of the urinary drainage from the bladder decreases elimination of bacteriuria therefore increases the risk of UTI.
  • Increase of the intravesical pressure is caused by detrusor hyperreflexia and DSD, or fixed outlet resistance and poor compliance in lower motor neuron lesions, in SCI patients. For more information, please refer to this
  • Increase of residual urine increases the risk of UTI [Merritt 1981]
  • Frequent need for the artificial drainage method.

2. Factors responsible for an increased risk of symptomatic UTI in the neurogenic bladder [National Institute on Disability and Rehabilitation Research Consensus Statement 1992; Garcia Leoni 2003]

  • Structural and physiologic factors
    • outlet obstruction: DSD
    • elevated intravesical pressure (high storage pressure, high pressure voiding)
    • incomplete voiding, large post-void residuals
  • VUR
    • over-distention of bladder
    • presence of stones in urinary tract
  • Risk factors related to behavior/ demographic characteristics
    • patients with a decreased functional independence or
    • those requiring complete or maximal assistance (cervical injuries);
  • Method of urinary drainage: indwelling urethral catheter

Key Points of This Section
  • Colonization of the bladder in neurogenic vesical dysfunction is nearly universal
  • Altered bladder defense mechanisms, CIC, incomplete emptying and elevated pressures all contribute to the colonization of the urinary tract.
  • Outcomes are less determined by bacteriuira than by abnormal bladder function associated with elevated bladder pressure.
  • Persons with low storage and voiding pressures do well despite bacteriuria.
  • Persons with symptoms are often treated for a urinary tract infection because bacteriuira is universal, but not often the cause of the problem.
  • Symptomatic urinary infection or suspected symptomatic infection is an absolute indication to check bladder and urethral and ureteral function for some underlying functional problem.

 

References

  • Merritt JL. Residual urine volume: correlate of UTI in patients with spinal cord injury. Arch Phys Med Rehabil. 1981 Nov;62(11):558-61.
  • The prevention and management of urinary tract infections among people with spinal cord injuries. National Institute on Disability and Rehabilitation Research Consensus Statement. January 27-29, 1992, J Am Paraplegia Soc. 1992 Jul;15(3):194-204.
  • Garcia Leoni ME, Esclarin De Ruz A. Management of urinary tract infection in patients with spinal cord injuries. Clin Microbiol Infect. 2003 Aug;9(8):780-5.

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