Urodynamics

Question 1

Cystometry: assesses, determines, purpose, indications

Answer 1

Assessesbladderpressure during filling

Determinesdetrusorandbladderfunction (activity, sensation, capacity, and compliance)

Measures the difference between pressure in urethral catheter and vaginal/rectal catheter (equals detrusor mmHg)

Indications: differentiate betweendetrusoroveractivity andstress incontinence + determine neurological abnormalities of thebladder(e.g.,hypotonic bladder)

Question 2

Uroflowmetry: assesses, determines, purpose, indications

Answer 2

Uroflowmetry
Assesses (measures) the volume ofurinevoided over time

pt pees into a funnel that measures volume and rate ofurineflow. Normal: a continuous, singlebell-shapedcurve withurinevolume> 200 mL(over15–30 seconds) and at a rate> 15 mL/sec

Abnormal: an abnormal curve orurinevolume at a rate< 15 mL/sec(aurinevolume< 150 mLincreases the risk of an inaccurate assessment)

Indications:

-Outlet obstruction(e.g., benignprostatichypertrophy, urethral overactivity,urethral stricturefollowing surgery)

• Weakdetrusor(e.g.,hypotonic bladder)
• Increased valsalva during voiding

Question 3

Pressure Flow study

Answer 3

Pressure-flow study

determines underlying mechanism of an abnormaluroflowmetryassessment

Measuresdetrusorpressure while voiding

Indications

• Increased valsalva during voiding
• Weakdetrusor(e.g.,hypotonic bladder)
• Outlet obstruction (e.g., benignprostatichypertrophy,
• urethral overactivity,urethral stricturefollowing surgery)

Question 4

Urethral pressure profile

Answer 4

Urethral pressure profile

Assesses intrinsic sphincter function

Measures the intraluminal urethral integrity at different pressures (filling and voiding pressures are measured under different types of provocation, e.g.,Valsalva maneuver,coughing, etc.)

*specialized urethral catheter withdrawn at a slow and steady rate from thebladderuntil it exits theexternal urethral meatus.

Indications

• Sphincter dysfunction (e.g., due tomultiparity, lowestrogenlevels)
• Urinarystress incontinence

Question 5

Postvoid residual volume

Answer 5

Postvoid residual volume

Measures the volume ofurinethat remains in thebladderafter voiding

May be performedusing straight catheterization orultrasoundof thebladder

Apostvoid residual volume< 50 mlis normal

Indications

- Outlet obstruction
- Weakdetrusor

Question 6

Leak point pressure

Answer 6

Leak point pressure

Assesses intrinsic sphincter function (but during dynamic testing, unlike urethral pressure profile testing)

Determines the intravesical pressure required to produce urine leakage in the presence of increased abdominal pressure (i.e., during valsalva maneuver) and the absence of detrusor contraction

Indications

• Sphincter dysfunction (e.g., due to multiparity, low estrogen levels)
• Urinary stress incontinence

Question 7

Electromyelogram(EMG)

Answer 7

Electromyelogram(EMG)

Studies the electrical potentials of depolarized muscle, specifically the neural pathways involved in micturition (by evaluating the segment of the sacralspinal cordinvolved)

Electrodes or a concentric needle are inserted into theurethral sphincter.

Indication: to determine neurological abnormalities of thebladder(e.g.,hypotonic bladder)