Bladder Emptying: Clinical Bladder Outlet Obstruction

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Fig. 19.1
(a) CMG and PFS, (b) expanded PFS segment, (c) pressure flow nomogram, (d) post-PFS non-invasive uroflow



Expanded PFS Segment (Fig. 19.1b). This segment of the tracing begins at the end of the storage phase labeled as MCC. (a) Prior to voiding the patient is asked to cough to assess accuracy of pressure lines. (b) The patient is then given permission to void. (c) The P ves rises rapidly without concomitant change in P abd confirming that the intravesical pressure change is due to a detrusor contraction. (d) Flow is initiated (e) and he voids 184 mL with a post-void residual of 21 mL. The Q max is 5 mL/s and the P det@Q max is 52 cm/H2O (f) and the flow pattern is continuous with a prolonged plateau phase. EMG activity has decreased throughout the voiding portion of the study. (g) Based on what we have interpreted as accurate pressure flow measurements the nomogram can be considered accurate and with a curve pressure/flow curve wholly contained in the obstructed zone (Fig. 19.1c).

The patient underwent refilling and the catheters were removed. He was asked to void in the uroflowmeter for a non-invasive uroflow (Fig. 19.1d).

This case demonstrates a classical presentation of outlet obstruction. The patient presents with obstructive type LUTS not well controlled with pharmacologic therapy and has urodynamic findings consistent with low flow/high pressure that meets the urodynamic definition of outlet obstruction. What the study does not do is identify the anatomic location of the obstruction. The differential diagnosis in this patient includes outlet obstruction from bladder neck dysfunction, BPH, or voiding dysfunction not identified by EMG. A urethral stricture is less likely but possible. Finally, if the non-invasive uroflow and PFS flow parameters were markedly different one would have had to consider that the PFS findings were secondary to artifact.



Case 2


Seventy-five-year-old male presents with symptoms of urgency, frequency, urge incontinence, and nocturia ×5. He has not been on any medication. He also has a history of Parkinson’s disease, which has been stable for the past 5 years. He denies any problems with urinary tract infection, hematuria, or previous pelvic surgery. Urinalysis negative. Non-invasive uroflow was attempted (Fig. 19.2a) but the patient only voided 90 mL with a PVR 10 mL. This is an insufficient volume to assess uroflow parameters. Urodynamic studies were ordered and depicted in Fig. 19.2b–d.

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Fig. 19.2
(a) Non-invasive uroflow, (b) CMG and PFS, (c) expanded PFS, (d) nomogram

CMG/PFS (Fig. 19.2b). Assessment of study validity demonstrates baseline pressures within normal range for standing patient and good concordance of the P ves and P abd at onset of studies. During the storage segment there is evidence of detrusor overactivity beginning at volume of 70 mL (a) and continuing with increasing amplitude until capacity at which time the patient could no longer hold back the flow. (b) The pressure lines are concordant after voiding is complete. Expanded PFS segment of the tracing is shown in Fig. 19.2c.

Expanded PFS (Fig. 19.2c). The initial event depicted in this tracing is a sudden rise in P ves that is not associated with a rise in P abd indicating that this is an involuntary detrusor contraction. (a) It is accompanied by a voluntary increase in EMG activity (b) and eventually a small amount of flow (c), representing an involuntary detrusor contraction associated with incontinence. As the patient begins to leak, the P det decreases slightly (d). The patient indicates he could no longer resist the urge and is given permission to void (e). As he begins to void, the flow rate rises, the EMG activity decreases (f), and the P det remains constant throughout the void. The Q max is 5 mL/s, the P det@Q max is 67 cm/H2O, and the flow pattern is continuous with a prolonged plateau. The patient voids 116 mL with a PVR of 11 mL. At the conclusion of the study, both P ves and P abd remain active and concordant during cough spike. (g) The entire pressure flow relationship is in the obstructed zone of the nomogram (Fig. 19.2d). The non-invasive uroflow and pressure flow tracings are consistent with one another suggesting this is not due to artifact from the study.

The study highlights a number of interesting findings in addition to the obstructed voiding parameters that may affect the selection of treatment. First, the patient has a small capacity bladder of 127 mL and high amplitude detrusor overactivity with incontinence. These findings are consistent with the patient’s symptoms of urgency, frequency, and urge incontinence.

The combination of a detrusor contraction and a concomitant increase in EMG activity displayed in this tracing are similar to the urodynamic findings one sees with detrusor external sphincter dyssynergia (DESD). What separates this tracing from DESD is the fact that the patient is voluntarily increasing the EMG activity in an effort to resist the urge to urinate whereas DSD occurs as an involuntary reflex. Without being present during the study or having proper annotation, there would be no way to distinguish by looking at the tracing alone. Another consideration in a patient with Parkinson’s Disease is pseudodyssynergia secondary to abnormal sphincter and pelvic floor relaxation during voiding, referred to as sphincter bradykinesia [20]. Since the EMG activity decreased the moment the patient was allowed to void, it is likely that the EMG activity in this study is mostly voluntary.

The patient clearly meets the definition for outlet obstruction secondary to BPH with high pressure/low flow that would likely respond to treatments aimed at reducing urethral resistance. However, he also has significant detrusor overactivity incontinence in the setting of Parkinson’s disease and is most bothered by the symptoms of urgency and urge incontinence as opposed to a low flow or incomplete emptying. He will have much more difficulty resisting the involuntary detrusor activity when the urethral resistance is lower. This patient may do better with anticholinergic therapy first to see how well the overactivity can be controlled before reduction of outlet resistance.


Case 3


Sixty-four-year-old male diabetic male who presents in consultation from his PCP with a history of recurrent UTIs. He denies LUTS. On physical exam, his is overweight, has normal genitals, a 40-g smooth prostate, decreased sensation in his feet bilaterally but an otherwise normal neurologic exam. Urinalysis positive for LE and Ketones. PSA 1.4. Non-invasive uroflow depicted in Fig. 19.3a. Patient voided a volume of 103 mL with a PVR of 380 mL. His Q max was 9 mL/s and a somewhat flattened flow pattern. He stated that was a normal void and he could not empty any more urine on a second try. CMG and PFS depicted in Fig. 19.3b.

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Fig. 19.3
(a) Non-invasive uroflow, (b) CMG and PFS, (c) nomogram

Baseline pressures are within normal range and pressure lines are concordant during cough spikes (a). No evidence of detrusor overactivity during storage and normal compliance at MCC of 619 mL. (b) Voiding phase demarcated (c) and patient initiated voided with a detrusor contraction (d) and an intermittent flow pattern (d). The second portion appears to be associated with valsalva. At the conclusion of the void there is concordance between P ves and P abd during cough spikes (g). Q max is 11 mL/s and P det@Q max is 29 cm/H2O. He voided a volume of 313 mL with a PVR 303 mL. The nomogram places him in the equivocal range for obstruction (Fig. 19.3c).

This patient has no clinical symptoms of obstruction but has an elevated post-void residual. The question is whether the poor bladder emptying is from obstruction or detrusor underactivity. The non-invasive flow is not helpful. While the flow rate is low, the pattern is continuous. The PFS demonstrates a large capacity bladder with delayed sensation. While he does void with a sustained detrusor contraction, the P det max is only 30 cm/H2O. The likely diagnosis for this patient is detrusor under activity, possibly related to his diabetes. However, he also likely has a relative outlet obstruction meaning that the relationship between the amount of pressure his bladder can generate and urethral resistance is unfavorable for him emptying efficiently. We would treat this patient as if he were obstructed, since by reducing urethral resistance the bladder pressure that he does generate may be sufficient to empty his bladder more completely.


Case 4


Forty-year-old male with frequency, urgency, decreased flow, and recurrent UTIs. He was found to have high PVRs by bladder ultrasound of over 800 mL. He was placed on CIC but found that the PVRs were very inconsistent in volume. He reported having many catheter volumes of 10–30 mL but then having to urinate again within a short time. He continued to have frequency that he could not explain by bladder volume and continued to have culture proven UTIs. He was scheduled for a videourodynamic study. The non-invasive uroflow is depicted in Fig. 19.4a. He voided 61 mL with an intermittent flow pattern, a Q max of 8 mL/s and a PVR of 400 mL.

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Fig. 19.4
(a) Non-invasive Uroflow, (b) CMG and PFS, (c) expanded PFS, (d) nomogram, (e) fluoroscopic image—capacity, (f) fluoroscopic image—void, (g) fluoroscopic image—filling

CMG and PFS depicted in Fig. 19.4b. Patient is standing, baseline pressures are within normal range, P ves 29 cm/H2O, P abd 26 cm/H2O (a) and both respond to cough with concordant spikes (b). In the middle of the tracing there is a sudden drop in both P abd and P ves and they remain concordant (c). This represents a point during the study that the patient became dizzy and was placed in the supine position. When he resumed the standing position, the pressures returned to their previous values and were again concordant during cough (d). The patient reached maximum capacity of 500 mL and was given permission to void (e).

The PFS portion of the study has been expanded in Fig. 19.4c starting at the point that the patient was given permission to void. (a) After a minute delay the P det begins to rise and he voids 25 mL before the P det returns to zero. Q max is 5 mL/s and P det@Q max is 67 cm/H2O and PVR of 475 mL. Filling resumed slowly over a 4-min period (c) until he developed a second urge and again he attempted to void. The second attempt to void (d) resulted in voided volume of 52 mL, a Q max of 5 mL/s, a P det@Q max of 85 cm/H2O, and PVR of 450 mL (e). The nomogram suggests obstruction (Fig. 19.4d).

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Jun 20, 2017 | Posted by in UROLOGY | Comments Off on Bladder Emptying: Clinical Bladder Outlet Obstruction

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