Editing Functional: Urodynamics (section)

== Voiding and Emptying phase ==

* Normal detrusor function: characterized by voluntarily initiated continuous contraction that leads to complete bladder emptying within a normal time span and in the absence of obstruction.
* Detrusor underactivity: a contraction of reduced strength and/or duration resulting in prolonged bladder emptying and/or a failure to achieve complete bladder emptying within a normal time span.
* Acontractile detrusor: no demonstrable contraction during UDS.

* Bethanechol supersensitivity test has been used to help distinguish the cause of detrusor underactivity as neurogenic and myogenic. However, it is unreliable and has limited role.
* '''Many authors recommend a minimum voided volume of 150mL to accurately assess uroflow'''
* '''Voiding pressure-flow study helps assess two critical parameters related to the bladder and bladder outlet: detrusor activity (normal vs. impaired) and outlet resistance (obstructed vs. unobstructed). Can identify 3 fundamental conditions:'''
*# '''Low (or normal) Pdet and high (or normal) flow rate: normal, unobstructed voiding'''
*# '''High Pdet and low (or normal) flow rate: obstruction'''
*# '''Low Pdet and low flow rate: detrusor underactivity'''
* '''Bladder outlet obstruction and detrusor underactivity in men'''
** '''<span style="color:#ff0000">Bladder outlet obstruction index (BOOI): Pdet@Qmax – 2(Qmax)</span>'''
*** '''<span style="color:#ff0000">≥ 40: obstructed</span>'''
*** Equivocal if 20-40
*** '''<span style="color:#ff0000">≤ 20: unobstructed</span>'''
** '''Bladder contractility index (BCI): Pdet@Qmax +5(Qmax)'''
*** '''>150: strong contractility'''
*** Normal contractility 100-150
*** '''Weak contractility if BCI <100'''
** These measures can become problematic when both detrusor underactivity and obstruction co-exist, such as in long-standing obstruction.
** '''Bladder outlet obstruction is associated with abnormalities of storage as well,''' presumably due to changes in ultrastructure that occur with obstruction.
*** DO and impaired compliance occur in conjunction with obstruction.
*** Approximately 2/3 of men with symptomatic BOO had detrusor overactivity that resolved 50-67% of the time with treatment of obstruction. '''Reduced compliance is also associated with obstruction and has been shown to improve with treatment of obstruction (TURP).'''
* '''Bladder outlet obstruction in females'''
** Obstruction when Qmax ≤12mL/sec and Pdet@Qmax ≥ 25cm H2O
** '''Large overlap of values between obstructed and unobstructed patients; absolute pressure and flow values are imprecise and another parameter (radiographic or clinical evidence of obstruction) is necessary for diagnosis.'''
** BOOI will grossly underestimate female BOO because females '''normally void at much lower pressures than males'''
* '''Sphincter coordination'''
** '''Failure of the sphincter to relax or stay completely relaxed during micturition is abnormal.'''
** '''Normally, EMG activity decreases before a voluntary bladder contraction'''
*** '''However, it is not abnormal for EMG activity to increase with an involuntary contraction as part of a guarding reflex to inhibit the idiopathic detrusor contraction, and this is known as pseudodyssynergia'''
**** '''Pseudodyssynergia: electromyographic sphincter “flare” during filling cystometry that is secondary to attempted inhibition of an involuntary bladder contraction by voluntary contraction of the striated sphincter'''
** '''<span style="color:#ff0000">Detrusor external sphincter dyssynergia (DESD)</span>'''
*** '''<span style="color:#ff0000">Occurs when there is an involuntary increase of external sphincter activity associated with detrusor activity and also with voiding.</span>'''
*** '''<span style="color:#ff0000">Caused by a neurologic lesion in the suprasacral spinal cord</span>'''
**** '''<span style="color:#ff0000">True DESD occurs only when there is a known neurologic lesion between the pons (infrapontine) above the sacral micturition center (Onuf nucleus S2-S4; suprasacral).</span>'''
**** '''If there is no neurologic lesion, the dyssynergia is considered to be a learned behavior and is known as dysfunctional voiding.'''
*** '''May be considered a urodynamic risk factor for upper tract deterioration.'''
**** DESD can produce profound changes as the detrusor involuntarily contracts against a relatively closed sphincter; '''over time, will''' '''result in high pressures and can even impair bladder compliance.'''
***** '''Long periods of elevated Pdet during bladder filling or voiding put the upper urinary tract at risk.'''
** '''Detrusor internal sphincter dyssynergia'''
*** '''Lack of coordination of the detrusor and internal sphincter or bladder neck'''
*** Insert figure