Background

Bladder pressure evaluation is usually included in urodynamics, which evaluates bladder, sphincter, and urethral ability to store and release urine.

Pressure inside the bladder is measured, and this gives useful information of the bladder in certain conditions like urinary incontinence, urinary retention or any other voiding dysfunction.

When obstruction occurs in patients with BPH or urethral stricture, the measurements of bladder pressure will help in the evaluation in the degree of obstruction and assist in management decisions.

Indications

Bladder Outlet Obstruction: In conditions where obstruction is suspected, such as benign prostatic hyperplasia (BPH) or urethral stricture, bladder pressure measurements can help assess the level of obstruction and assist in management decisions.

Neurogenic Bladder: For patients with spinal cord injuries, multiple sclerosis or other neurological diseases that affect the bladder’s sensitivity, the measurement of the pressure inside the bladder allows the evaluation of bladder compliance, detrusor overactivity, or the potential for high pressure within the bladder that can cause renal or incontinence problems.

Urodynamics Evaluation: During urodynamic studies, bladder pressure is assessed to evaluate bladder storage function and voiding pressures, which can assist in diagnosing conditions like incontinence, overactive bladder, and detrusor instability.

Intra-abdominal Pressure Monitoring: In critical care or surgical settings, bladder pressure is sometimes used as an indirect measure of intra-abdominal pressure (IAP). This can help assess conditions like abdominal compartment syndrome, which can affect organ function.

Contraindications

Bladder or Urinary Tract Obstruction: Any obstruction of the urinary tract can cause difficulties or inaccuracies in measuring bladder pressure by creating any condition that blocks the flow of urine into the bladder, such as urinary retention or severe bladder outlet obstruction.
Active urinary tract infection or cystitis: Conducting the evaluation on a patient with an active urinary tract infection may be painful, exacerbate infection, or even cause spread of infection.
Bladder trauma or recent surgery: In those patients who have had recent trauma to the bladder or have undergone recent bladder surgery, bladder pressure assessment may aggravate the injury or interfere with healing.
Severe Abdominal Distension: In the presence of severe abdominal bloating or distension, the procedure may not be as reliable, and the pressure assessment may be affected.

Outcomes

Equipment’s 

Urodynamic Equipment

Cystometer (CMG)

Intravesical Pressure Catheter

Urethral Pressure Profile Manometry (UPP)

Transabdominal Bladder Pressure Measurement

Electromyography (EMG)

Cystometry System

Patient Preparation 

Pre-Procedure Instructions: 

Hydration: Patients may be instructed to drink a specific amount of water before the procedure to ensure the bladder is filled adequately. A full bladder is typically needed for accurate pressure measurement.

Emptying the Bladder: Patients should be instructed to empty their bladder before arriving at the appointment if instructed by the healthcare provider.

Avoid Diuretics or Medications: Patients may be asked to avoid certain medications (such as diuretics or bladder medications) prior to the procedure, as these may interfere with results.

Clothing:

Wear Comfortable Clothing: Patients should wear loose, comfortable clothing that allows easy access to the lower abdomen or genital area.

Pre-Procedure Evaluation: 

Medical History: A review of the patient’s medical history, including any conditions affecting the bladder or urinary tract, is important.

Urinary Symptoms: The healthcare provider may ask about symptoms such as incontinence, urgency, or frequency of urination.

Consent: Ensure that the patient understands the procedure and has provided informed consent.

Patient Positioning  

Supine Position (Lying on Back): The patient lies flat on their back on an examination table with the legs straight or slightly bent at the knees. This is most often used during cystometry to study bladder compliance, volume, and pressure with filling.
Sitting Position: The patient usually sits on a uroflowmetry device while urinating into a specialized container that measures urine flow rate and volume.

Preparation

Patient Consent: Ensure the patient understands the procedure and give consent.

Positioning: The patient is asked to lie down or sit in a comfortable position. The procedure is typically performed in a urodynamic or diagnostic room.

Sterility: Cleanse the genital area to prevent infection, using sterile technique.

Insertion of Catheter 

Cystometric Catheter: A thin catheter is inserted into the bladder through the urethra. This catheter is used to measure the pressure inside the bladder during the test.

Rectal Pressure Measurement: A second catheter (or a pressure sensor) may be inserted into the rectum to measure abdominal pressure. This helps distinguish between bladder pressure and abdominal pressure during the test.

Filling the Bladder 

Instillation of Fluid: The bladder is filled with a sterile fluid (typically saline or water) through the catheter. This is done slowly and steadily to avoid causing discomfort.

Monitoring Pressure: During bladder filling, the pressure inside the bladder is measured by the catheter. The filling is continued until the patient feels the urge to urinate or until a predetermined pressure or volume is reached.

Patient's Feedback

Monitor Sensation: The patient is asked to report any sensations, such as the first desire to void, the strong urge, or discomfort. These responses help assess bladder sensation and capacity.

Cough or Valsalva Maneuver: Sometimes, the patient is asked to cough or perform a Valsalva maneuver (bearing down) to assess how the bladder pressure responds to changes in abdominal pressure.

Pressure Measurement During Bladder Filling

The bladder pressure is continuously monitored during the filling process. A normal bladder filling pattern would show a gradual rise in pressure without sudden spikes.

Any abnormal increases in pressure, or sensations of pain or urgency, may indicate issues like detrusor overactivity or impaired compliance.

Assessment During Bladder Storage

Bladder Compliance: As the bladder is being filled the need for it to expand without a marked increase is determined, this is known as compliance. Low compliance may be due to the latter that has to do with bladder dysfunction.
The maximal bladder pressure is determined, and the volume before a desire to void is mentioned by the patient is listed.

End of Filling Phase

The examiner shouldstop the test and the patient can be encouraged to void or further investigations could be done if the investigator is able to gain the desired pressure or volume in the bladder.

Post-Test Instructions

Bladder Emptying: Often patient urination with or without a second catheter or a flow meter follows the bladder filling and pressure measurement, but the bladder emptying process is part of a different procedure.
Post-Procedure Care: After the test is completed, the catheter can be removed by the doctor while the patient can be instructed to take liquids or report any bad signs which include, pain and urine retention among others.

Data Analysis

The results of the bladder pressure and the response to filling are analysed by a urologist or other healthcare providers to diagnose conditions like urinary incontinence, bladder outlet obstruction, or bladder storage issues.

Complications 

Infection:
Urinary Tract Infections (UTIs): Catheterization of the bladder increases the risk of infection. This is a significant concern in critically ill patients or those with long-term catheter use.
Sepsis: If the infection worsens, it may cause sepsis, which is a life-threatening condition.
Catheter-related Complications:
BladderTrauma: The catheter may be inserted improperly, causing damage to the bladder or urethra.
Hemorrhage: The catheter may damage blood vessels in the bladder, resulting in bleeding.
Catheter malposition: The catheter may become misplaced or placed incorrectly, resulting in inaccurate pressure readings or bladder injury.

False Readings: 

Incorrect Calibration: Inaccurate readings can result from improper calibration of the device, leading to incorrect management decisions.

Positioning Issues:

Pressure measurement can also be influenced by the positioning of the catheter, position of the patient or the fact that the pressure measurement was not adequately zeroed.

Discomfort and Pain: The procedures such as inserting or keeping the catheter in place for sometimes may lead to discomfort or pain which un-favours patients.

Bladder Overdistention:

Pressure from the catheter: In some cases, excessive pressure may lead to bladder over distension, and this is likely to causes discomfort of the bladder or even injury of the bladder.

Urinary Retention: When the catheter hinders the normal passing of urine it causes urine to build up resulting to a distended bladder with increased pressure.

Hyperkalemia: If the bladder pressure measurement technique requires the use of catheter for an extended period there may be complications thereby leading to urinary retention the patient may experience Hyper Kalemia.

References

Measurement of Urinary Bladder Pressure: A Comparison of Methods – PubMed

References

Measurement of Urinary Bladder Pressure: A Comparison of Methods – PubMed