Underactive Bladder

Author: Kevin Rademakers
Date of last amendment: October 2018

Current definitions:

Underactive bladder: (symptom) Underactive bladder is characterized by a slow urinarystream, hesitancy and straining to void,awith or without a feeling of incomplete bladder emptying sometimes with storage symptoms. (1)

Normal detrusor contractile function: Normal voiding in men is achieved by an adequate continuous detrusor contraction that leads to complete bladder emptying within a normal time span. It depends on central initiation and stimulation of the reflexes involved. The amplitude of the detrusor contraction (detrusor contraction strength/power) tends to increase in response to any increased urethral resistance until the bladder is empty. (2)

Detrusor underactivity (DU): (sign) Low detrusor pressure or short detrusor contraction time, usually in combination with a low urine flow rate resulting in prolonged bladder emptying and/or a failure to achieve complete bladder emptying within a normal time span measured by urodynamics. (c.f. the term “hypocontractile detrusor” or detrusor hypocontractility describes a detrusor contraction of reduced strength). Detrusor underactivity can be of neurogenicor non-neurogenic origin. (2)

Past definitions:

Normal detrusor function: Normal voiding is achieved by a voluntarily initiated continuous detrusor contraction that leads to complete bladder emptying within the normal time span, and in the absence of obstruction. For a given detrusor contraction, the magnitude of the recorded pressure rise will depend on the degree of outlet resistance. (3) Detrusor underactivity: A contraction of reduced strength and/or duration, resulting in prolonged bladder emptying and/or failure to achieve complete bladder emptying within a normal time span. (3)

Controversies:

-“LUTS are not disease specific. The symptoms of hesitancy, straining to void, and a slow urinary stream can be characteristic of both bladder outflow obstruction (BOO) and detrusor underactivity (DU)”. These sentences in the working group of UAB terminology report make clinical utility of the current working definition of underactive bladder difficult for the general urologist. How do we define one as a UAB patient when the signs/symptoms show overlap with BOO?
-Key symptoms of UAB have not been defined. This may be because of selection of the patient population or due to the lack of existence of such symptoms.
-What is the relationship between the working symptom definition of UAB and the urodynamic definition DU? Is there even an overlap between entities? (4) This is of importance to eventually adequately phenotype UAB patients.
-The aforementioned controversies with regard to UAB terminology should be solved first before we discuss the potential therapeutics options of UAB. This to avoid numerous publications with inadequate inclusion of patients and potentially false outcome of the studies as a result. And to avoid incorrect treatment of patients.

References

  1. Chapple CR, Osman NI, Birder L, et al. Terminology report from the International Continence Society (ICS) Working Group on Underactive Bladder (UAB). Neurourology and Urodynamics. 2018;1–4.
  2. Haylen B, D’Ancona C, Oelke M, Herschorn S, Abranches-Monteiro L et al. The international continence society (ICS) report on the terminology for adult male lower urinary tract and pelvic floor symptoms and dysfunction. Manuscript to be submitted in 2019.
  3. Abrams P, Cardozo L, Fall M, Griffiths D, Rosier P, Ulmsten U, et al. The standardisation of terminology of lower urinary tract function: report from the Standardisation Sub-committee of the International Continence Society. Neurourol Urodyn. 2002;21(2):167-78. PubMed PMID: 11857671. Epub 2002/02/22. eng.
  4. Tarcan T, Rademakers K,Arlandis S, von Gontard A, van Koeveringe GA, Abrams P. Do the definitions of the underactive bladder and detrusor underactivity help in managing patients: International Consultation on Incontinence Research Society (ICI-RS) Think Tank 2017? Neurourology and Urodynamics. 2018;37:S60–S68
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