Urodynamic studies (UDS) Expertise of Dr. Yasir Iqbal

Urodynamic Studies (UDS), also known as Urodynamic Testing (UDT), are a series of diagnostic procedures used in urology to evaluate how effectively the bladder, urethra, and pelvic floor muscles are functioning. These tests are crucial for diagnosing and managing conditions such as:

• Urinary incontinence

• Overactive bladder (OAB)

• Urinary retention

• Neurogenic bladder

• Recurrent urinary tract infections

• Bladder outlet obstruction

UDS measures how well the bladder stores and empties urine, detects abnormal bladder contractions, and helps identify blockages or nerve-related dysfunction. By providing objective insights into urinary tract function, urodynamic testing enables clinicians to tailor the most effective treatment plans—whether medical, surgical, or behavioral.

⚙️ How the UDS Procedure is Performed

The UDS procedure is typically done in a urology clinic or hospital setting and takes about 30–60 minutes. It is minimally invasive and usually performed without general anesthesia.

🩺 Step-by-Step Procedure

1. Pre-Test Preparation

• The patient is asked to arrive with a comfortably full bladder.

• A brief medical history and current symptoms are reviewed.

• Informed consent is taken.

• No fasting or sedation is usually needed.

• In some cases, a mild antibiotic may be given to prevent infection.

2. Initial Uroflowmetry

• The patient urinates into a special uroflowmeter funnel that measures:

  • Flow rate

  • Voiding time

  • Voided volume

• This gives a baseline understanding of how urine exits the bladder.

3. Post-Void Residual (PVR) Measurement

• After voiding, the amount of urine left in the bladder is measured using:

  • A bladder scan (ultrasound), or

  • A catheter inserted briefly to drain and measure residual urine.

4. Catheter Placement

• Two thin catheters are inserted:

  • One into the bladder to fill it with sterile fluid and measure bladder pressure.

  • One into the rectum (or vagina) to measure abdominal pressure.

• In some cases, EMG pads are placed near the anus or perineum to assess pelvic floor muscle activity.

5. Bladder Filling (Cystometry Phase)

• The bladder is slowly filled with room-temperature sterile saline or contrast fluid.

• The patient is asked to report:

  • First sensation of filling

  • Normal urge to void

  • Strong urge to void

• During this, the system measures:

  • Bladder compliance

  • Detrusor (bladder muscle) activity

  • Involuntary contractions

6. Provocative Maneuvers

• The patient may be asked to:

  • Cough

  • Strain (Valsalva maneuver)

  • Change position

• This checks for stress incontinence or abnormal contractions.

7. Voiding (Pressure-Flow Study)

• Once the bladder is full, the patient is asked to urinate with the catheters in place.

• Measures include:

  • Detrusor pressure during voiding

  • Urethral resistance

  • Urine flow rate

• Helps identify obstruction vs underactive bladder.

8. Video UDS (If Ordered)

• In some cases, contrast dye is used and real-time X-ray (fluoroscopy) is performed during filling and voiding.

• Provides detailed anatomical images of bladder and urethra.

9. Post-Test Care

• Catheters are gently removed.

• Patient is encouraged to drink plenty of fluids to flush the bladder.

• May experience mild burning or discomfort for a day or two.

• Results are analyzed and explained by the urologist in a follow-up visit.

✅ Duration:

30–60 minutes

🚫 Anesthesia:

Usually not required

🧼 Risks:

Minimal – low risk of UTI, temporary discomfort

🎯 Purpose of UDS

To objectively assess bladder function and guide treatment for:

• Urinary incontinence (stress, urge, mixed)

• Urinary retention

• Neurogenic bladder

• Overactive bladder (OAB)

• Recurrent urinary tract infections

• Bladder outlet obstruction

• Before complex urological surgeries (e.g., incontinence surgery, prostate surgery)

🧪 Types of Urodynamic Tests

Urodynamic testing involves several specialized procedures that assess different aspects of bladder and urethral function. Each test provides specific information to guide diagnosis and treatment.

1. Uroflowmetry

Purpose: Measures how quickly and completely you empty your bladder.
How it works:

• You urinate into a special funnel connected to a machine.

• It records flow rate, voided volume, and time to empty.

✅ Useful for: Suspected urinary obstruction, weak bladder, BPH, or incomplete voiding.

2. Post-Void Residual (PVR) Measurement

Purpose: Determines how much urine remains in the bladder after urination.
How it works:

• Measured by bladder ultrasound or catheterization right after voiding.

✅ Useful for: Detecting incomplete bladder emptying and risk of infections.

3. Cystometry (CMG – Cystometrogram)

Purpose: Assesses bladder's storage function and sensitivity.
How it works:

• A thin catheter fills the bladder with sterile fluid.

• A second sensor (in the rectum or vagina) monitors abdominal pressure.

• Measures bladder pressure, capacity, compliance, and detrusor activity during filling.

✅ Useful for: Overactive bladder, stress/urge incontinence, neurogenic bladder.

4. Pressure-Flow Study

Purpose: Evaluates bladder muscle strength and possible outlet obstruction during urination.
How it works:

• Performed during voiding phase of cystometry.

• Measures detrusor pressure vs urine flow rate.

✅ Useful for: BPH, stricture, underactive bladder.

5. Electromyography (EMG)

Purpose: Monitors nerve and muscle coordination in the pelvic floor.
How it works:

• Surface electrodes (or needle electrodes) record pelvic muscle and sphincter activity.

• Often combined with CMG.

✅ Useful for: Neurogenic bladder, detrusor-sphincter dyssynergia.

6. Leak Point Pressure Testing

Purpose: Measures the pressure at which urine leaks from the bladder.
Types:

• Valsalva Leak Point Pressure (VLPP): Leak during abdominal strain

• Detrusor Leak Point Pressure (DLPP): Leak from involuntary contractions

✅ Useful for: Stress incontinence, risk of upper tract damage in neurogenic bladder.

7. Video Urodynamics (Fluoroscopic UDS)

Purpose: Combines pressure testing with imaging.
How it works:

• Contrast fluid is instilled in the bladder.

• X-rays or fluoroscopy images are taken during filling and voiding.

• Allows anatomic visualization along with functional data.

✅ Useful for: Complex or unclear cases, neurogenic bladder, fistula, reflux, anatomical abnormalities.