Cystometry: Bladder Pressure Test & What to Expect
Cystometry is a diagnostic test that measures the pressure inside your bladder as it fills and empties. This urodynamic study helps doctors evaluate how well your bladder stores and releases urine, diagnose conditions like overactive bladder or urinary incontinence, and plan appropriate treatment. The test is generally well-tolerated and takes about 30-60 minutes.
Quick Facts: Cystometry
Key Takeaways
- Cystometry measures bladder pressure during filling and emptying to evaluate bladder function and diagnose urinary conditions
- The test is generally not painful - most patients experience only mild discomfort when the catheter is inserted
- Preparation is simple - arrive with a comfortably full bladder and inform your doctor about medications
- Results help guide treatment for overactive bladder, incontinence, neurogenic bladder, and obstruction
- Complications are rare - urinary tract infection occurs in about 2-5% of patients
- Normal activities can resume immediately after the procedure; drink plenty of fluids afterward
- Both children and adults can undergo cystometry when bladder problems need investigation
What Is Cystometry and Why Is It Performed?
Cystometry is a urodynamic test that measures the pressure inside your bladder as it fills with fluid and when you urinate. It evaluates how your bladder muscle (detrusor) functions, its capacity to hold urine, your sensation of bladder fullness, and the coordination between your bladder and the sphincter muscles that control urination.
Your bladder is a muscular organ that serves as a reservoir for urine produced by your kidneys. For the urinary system to function properly, your bladder must expand smoothly as it fills, store urine without leaking, and contract effectively when you decide to urinate. Cystometry provides objective measurements of these functions, helping doctors understand what might be causing your urinary symptoms.
The test is named after the Greek words "kystis" (bladder) and "metron" (measure), literally meaning "bladder measurement." It has been used in clinical medicine since the early 20th century and remains the gold standard for evaluating bladder function. Modern cystometry uses sophisticated electronic equipment that continuously records pressure changes and generates detailed graphs for analysis.
During cystometry, sensors measure two types of pressure: intravesical pressure (the total pressure inside your bladder) and abdominal pressure (measured in the rectum to account for external forces like coughing). The difference between these measurements gives the detrusor pressure, which reflects the actual contraction force of your bladder muscle.
Why Cystometry Is Ordered
Your doctor may recommend cystometry if you experience urinary symptoms that haven't responded to initial treatments or when the cause of your symptoms is unclear. The test provides crucial information that cannot be obtained through physical examination or imaging alone. Understanding how your bladder actually functions under controlled conditions allows for more accurate diagnosis and targeted treatment.
Common reasons for ordering cystometry include:
- Urinary incontinence: Involuntary leakage of urine, whether during physical activities (stress incontinence) or with sudden urges (urge incontinence)
- Overactive bladder: Frequent urination, urgency, and nighttime urination that disrupts sleep
- Difficulty emptying the bladder: Weak stream, straining to urinate, or feeling of incomplete emptying
- Neurological conditions: Diseases affecting the nervous system (multiple sclerosis, spinal cord injury, Parkinson's disease) that may impact bladder control
- Before or after surgery: To assess bladder function before pelvic surgery or to evaluate results after surgical treatment
- Recurrent urinary tract infections: When infections may be related to incomplete bladder emptying
- Children with bedwetting or daytime wetting: When behavioral and basic treatments haven't worked
Conditions Diagnosed by Cystometry
Cystometry can identify several specific bladder disorders that cause similar symptoms but require different treatments:
| Condition | Cystometry Findings | Typical Symptoms |
|---|---|---|
| Detrusor Overactivity | Involuntary bladder contractions during filling | Urgency, frequency, urge incontinence |
| Detrusor Underactivity | Weak or absent bladder contractions during voiding | Difficulty starting urination, weak stream, incomplete emptying |
| Bladder Outlet Obstruction | High pressure with low flow during urination | Straining, slow stream, hesitancy |
| Reduced Bladder Compliance | Abnormally high pressure rise during filling | Frequency, urgency, may have no symptoms |
| Stress Urinary Incontinence | Leakage with cough/strain without bladder contraction | Leakage with physical activity |
How Should You Prepare for Cystometry?
To prepare for cystometry, arrive with a comfortably full bladder by not urinating for 2-3 hours before the test. Inform your doctor about all medications you take, as some may need to be stopped temporarily. You may need to provide a urine sample beforehand to rule out infection.
Proper preparation for cystometry is relatively simple but important for obtaining accurate results. The test measures how your bladder responds to filling under normal conditions, so factors that artificially affect bladder function need to be controlled. Your healthcare provider will give you specific instructions based on your individual situation.
The most important preparation step is managing your bladder fullness before the appointment. You should avoid urinating for approximately 2-3 hours before the scheduled test time. This ensures that your bladder contains some urine when you arrive, which allows the initial part of the test (measuring how fast you urinate) to be performed. However, don't drink excessive fluids or hold your urine to the point of discomfort, as this could affect the results.
Medications That May Need to Be Adjusted
Several types of medications can affect bladder function and may interfere with cystometry results. Always tell your doctor about every medication you take, including over-the-counter drugs and supplements. Your doctor will decide which medications should be stopped and for how long - typically about one week before the test. Never stop taking prescribed medications without your doctor's guidance.
Medications that commonly affect bladder function include:
- Anticholinergics/antimuscarinics: Oxybutynin, tolterodine, solifenacin, and similar drugs prescribed for overactive bladder
- Beta-3 agonists: Mirabegron and vibegron used for overactive bladder
- Alpha-blockers: Tamsulosin, alfuzosin, and similar drugs for prostate enlargement
- Antidepressants: Tricyclic antidepressants and some SSRIs can affect bladder function
- Antihistamines: Diphenhydramine and similar drugs have anticholinergic effects
- Diuretics: May need timing adjustment to avoid excessive urine production during the test
Urine Testing Before Cystometry
A urine sample is typically required before cystometry to check for urinary tract infection. If bacteria are present in your urine, the test may need to be postponed because performing cystometry during an active infection increases the risk of complications and can produce misleading results. Your doctor may ask you to provide a urine sample at your primary care office about 10 days before the scheduled procedure, or you may give a sample when you arrive for the test.
Some facilities also measure the residual urine volume (the amount left in your bladder after urinating) using ultrasound before the procedure begins. This provides additional information about how well your bladder empties.
Other Preparation Tips
- Empty your bowels: It's helpful to have a bowel movement before the procedure, as a full rectum can affect bladder measurements and comfort
- Wear comfortable clothing: Choose loose-fitting clothes that are easy to remove from the waist down
- Bring a list of medications: Even if you've already discussed medications, bring a complete list to your appointment
- Arrange transportation if needed: While most people can drive themselves home, some prefer to have someone accompany them
- Allow adequate time: Plan to be at the facility for at least 60-90 minutes
Preparing Children for Cystometry
When a child needs cystometry, parents play an important role in preparation. Children often feel anxious about medical procedures, and honest, age-appropriate explanations can help reduce fear. You can explain that the test helps the doctor understand how their bladder works and that it might feel a little strange but shouldn't hurt badly.
Many pediatric facilities have child life specialists who can help prepare children using play, diagrams, or videos. Bringing a favorite toy or comfort item can also help. Parents are typically allowed to stay with their child throughout the procedure to provide reassurance and support.
How Is Cystometry Performed Step by Step?
During cystometry, a thin catheter is inserted through your urethra into the bladder while you lie on an examination table. The bladder is slowly filled with sterile saline solution while sensors measure pressure continuously. You report sensations during filling, then urinate while measurements continue.
Understanding what happens during cystometry can help reduce anxiety and prepare you for the experience. The procedure follows a standardized protocol established by the International Continence Society to ensure consistent, reliable results. While the specific equipment and room setup may vary between facilities, the basic steps remain the same.
The entire process typically takes 30-60 minutes from start to finish, though this can vary depending on your specific situation and whether additional tests are performed. Throughout the procedure, medical staff will explain what they're doing and check on your comfort level.
Initial Assessment and Uroflowmetry
The test usually begins with uroflowmetry - a simple measurement of how you urinate under normal conditions. You'll be asked to urinate into a special toilet or funnel connected to a measuring device. This equipment records the volume of urine, the rate of flow, and the time it takes to empty your bladder. The resulting flow curve provides valuable information about bladder function and any potential obstruction.
After uroflowmetry, a healthcare provider may use ultrasound to measure any urine remaining in your bladder (post-void residual). Normal bladders typically empty almost completely, leaving less than 50-100 ml of residual urine.
Catheter Placement
For the main part of the cystometry test, you'll be asked to lie down on an examination table. The healthcare provider will clean the genital area with antiseptic solution and apply a local anesthetic gel to the urethra. This gel numbs the area and also lubricates the catheter for easier insertion.
A thin, flexible catheter is then gently inserted through the urethra into the bladder. The catheter has pressure sensors built in or connected to it. Most people feel pressure or a strange sensation during catheter insertion, but it is not typically painful. If you experience significant discomfort, tell the medical team so they can take steps to improve your comfort.
The catheter has a small balloon near its tip that is inflated with sterile water once inside the bladder. This keeps the catheter in place and prevents it from slipping out during the test. Any urine in the bladder at this point is drained and measured.
Rectal Catheter (Optional)
In many cases, a second small catheter is placed in the rectum. This measures abdominal pressure, which is important because activities like coughing, laughing, or straining increase pressure on the bladder from outside. By measuring abdominal pressure separately, the equipment can calculate the true pressure generated by the bladder muscle itself.
The rectal catheter is smaller than the bladder catheter and is usually well-tolerated. Some people find it mildly uncomfortable but not painful.
Filling Phase
Once the catheters are in place, the filling phase begins. Sterile saline solution (salt water) at room or body temperature is slowly infused into the bladder through the catheter. The typical filling rate is 25-50 ml per minute for adults, though slower rates may be used for certain patients or conditions.
During filling, you'll be asked to report specific sensations:
- First sensation of bladder filling: When you first notice the bladder is filling
- First desire to void: When you feel a normal urge to urinate
- Strong desire to void: When you feel a strong need to urinate but could delay if necessary
- Maximum capacity: When you feel you absolutely must urinate
The equipment continuously records the pressure inside your bladder during filling. Normally, the bladder should accommodate increasing volumes with only minimal pressure rise - this is called compliance. The medical team watches for abnormal pressure spikes that might indicate involuntary bladder contractions.
Provocation Maneuvers
During or after filling, you may be asked to perform certain actions to test your bladder's response. These might include coughing, standing up, listening to running water, or having your lower abdomen pressed gently. These "provocation maneuvers" can trigger involuntary bladder contractions or leakage that wouldn't occur at rest, providing additional diagnostic information.
Voiding Phase (Pressure-Flow Study)
When your bladder feels full, you'll be asked to urinate while the measurements continue. This part of the test, called a pressure-flow study, evaluates how well your bladder contracts and whether there is any obstruction to urine flow. You'll urinate into a special collection device that measures flow rate.
Some people find it difficult to urinate in this setting, which is understandable given the unusual circumstances. The medical team is experienced in helping patients relax, and they may provide privacy or use techniques like running water to help initiate urination.
Test Completion
After you've emptied your bladder, the catheters are removed. This is typically quick and causes only brief discomfort. The procedure is then complete, and you can get dressed. The entire process, including filling the bladder multiple times if needed, typically takes about one hour.
What Happens After Cystometry?
After cystometry, you can resume normal activities immediately. Most people feel fine afterward, though some experience mild burning with urination for a day or two. Drinking plenty of fluids helps flush the urinary system and reduces the risk of infection.
One of the advantages of cystometry is that it requires no recovery time. Unlike procedures that require sedation or anesthesia, cystometry uses only local anesthetic gel, so you remain fully alert and can leave the facility as soon as the test is complete. There are no restrictions on driving, working, or other activities.
The most common experience after cystometry is mild irritation of the urethra from the catheter. This may cause a slight burning sensation when you urinate for the next day or two. This is normal and should resolve quickly. Drinking extra fluids - about 8-10 glasses of water over the next 24-48 hours - helps dilute the urine and flush any bacteria that might have entered the bladder during the procedure.
What to Expect in the Days Following
Most people experience no problems after cystometry. You might notice:
- Mild discomfort when urinating: Burning or stinging that resolves within 1-2 days
- Slightly pink urine: A tiny amount of blood is normal and should clear quickly
- Urge to urinate more frequently: This typically resolves within a few hours
- Mild lower abdominal discomfort: Usually resolves within a day
- Drink 8-10 glasses of water in the 24 hours after the test
- Avoid caffeinated beverages and alcohol for 24 hours (these can irritate the bladder)
- Take a warm bath to help relieve any discomfort
- Over-the-counter pain relievers like acetaminophen can help if needed
What Are the Risks and Complications of Cystometry?
Cystometry is a safe procedure with minimal risks. The most common complication is urinary tract infection, occurring in about 2-5% of patients. Other rare complications include temporary discomfort, minor bleeding, and very rarely, bladder perforation. Most people experience no complications at all.
The safety profile of cystometry has been well-established through decades of clinical use. The International Continence Society and other professional organizations have developed standardized protocols that minimize risks. Nevertheless, like any medical procedure involving catheterization, there are some potential complications to be aware of.
Urinary tract infection (UTI) is the most frequent complication, though it still affects only a small percentage of patients. The risk exists because inserting a catheter can introduce bacteria into the bladder. The sterile technique used during the procedure significantly reduces this risk. Symptoms of UTI typically appear within a few days of the procedure and include:
- Burning or pain when urinating that worsens instead of improving
- Frequent urge to urinate
- Cloudy or foul-smelling urine
- Blood in the urine (more than just slight pink tinge)
- Lower abdominal or back pain
- Fever or chills
Contact your healthcare provider or seek medical care if you experience any of the following after cystometry:
- Fever above 38°C (100.4°F)
- Severe pain in the lower abdomen or back
- Inability to urinate
- Heavy bleeding in the urine
- Signs of infection that worsen after 2-3 days
Other rare complications include:
- Hematuria: Blood in the urine from minor trauma during catheter insertion (usually resolves within 24-48 hours)
- Urinary retention: Temporary difficulty urinating after catheter removal (rare)
- Bladder perforation: Extremely rare injury to the bladder wall (less than 0.1% of procedures)
- Allergic reaction: Very rare reaction to the local anesthetic or catheter material
When and How Will You Get Your Cystometry Results?
Preliminary cystometry results are often available immediately after the test, as measurements are recorded in real-time. A complete interpretation and formal report typically takes a few days to a few weeks, after which your doctor will discuss the findings and recommend treatment options.
The urodynamics equipment generates graphs and numerical data during the test, so the healthcare provider performing the procedure can often see preliminary results immediately. They may give you some initial feedback about obvious findings. However, a thorough analysis of the data requires time, and a specialist (usually a urologist or urogynecologist) will review the results carefully before making a formal report.
The formal report typically takes a few days to a few weeks to complete, depending on the facility's workflow. The report is sent to the doctor who referred you for the test. You will usually discuss the results at a follow-up appointment, where your doctor can explain what was found and what it means for your treatment.
Understanding Your Results
Cystometry reports include several measurements and observations:
| Measurement | Normal Range | What It Means |
|---|---|---|
| Bladder Capacity | 300-600 ml | Maximum volume the bladder can hold comfortably |
| First Desire to Void | 150-250 ml | Volume at which you first feel the urge to urinate |
| Compliance | >40 ml/cmH2O | How well the bladder stretches during filling |
| Detrusor Pressure at Qmax | <40 cmH2O (women) <50 cmH2O (men) |
Bladder pressure at maximum flow rate |
| Post-Void Residual | <50 ml | Urine remaining after urination |
Treatment Based on Results
The treatment recommended after cystometry depends entirely on what the test reveals. Different bladder problems require different approaches:
- Detrusor overactivity: May be treated with bladder training, medications (antimuscarinics or beta-3 agonists), botulinum toxin injections, or nerve stimulation
- Detrusor underactivity: May involve clean intermittent catheterization, medications, or strategies to improve emptying
- Bladder outlet obstruction: May require medications, minimally invasive procedures, or surgery depending on the cause
- Stress urinary incontinence: May be treated with pelvic floor exercises, pessaries, or surgical procedures
- Reduced bladder compliance: May require medications, intermittent catheterization, or surgery to protect the kidneys
When Might Cystometry Need to Be Rescheduled?
Cystometry may need to be rescheduled if you have an active urinary tract infection, are menstruating, or accidentally urinated just before the test. Contact the facility to reschedule if any of these situations apply.
Sometimes cystometry cannot be performed as scheduled due to circumstances that would affect the results or increase risks. If the test needs to be postponed, it's important to reschedule promptly so that diagnosis and treatment can proceed.
The most common reasons for postponement include:
- Urinary tract infection: If your pre-test urine sample shows bacteria, the test will be postponed until the infection is treated
- Menstruation: For women, the test is typically rescheduled to avoid the menstrual period
- Empty bladder: If you accidentally urinated shortly before the test, you may need to return another day when you can arrive with a full bladder
- Acute illness: Fever or other acute medical conditions may warrant postponement
- Certain medications: If you haven't stopped bladder-affecting medications as instructed, the test may need to wait
How Can You Participate in Your Care?
Active participation in your healthcare leads to better outcomes. Ask questions, understand the information provided, and communicate openly with your medical team. Interpreter services and accessibility accommodations are available if needed.
Being an informed and active participant in your medical care helps ensure that you receive appropriate treatment and understand your options. Don't hesitate to ask questions about cystometry or any aspect of your urinary health. Healthcare providers are there to help you understand your condition and the tests being performed.
Before and after cystometry, consider asking your healthcare provider:
- What specific conditions are you looking for with this test?
- How will the results affect my treatment options?
- Are there any alternatives to this test?
- What should I do if I have problems after the test?
- When and how will I receive my results?
- What questions should I ask at my follow-up appointment?
If you have difficulty understanding medical information due to language barriers, hearing impairment, or other factors, accommodations are available. Many healthcare facilities provide interpreter services, written materials in multiple languages, and assistive devices for those with hearing or vision impairments. Ask about these services when scheduling your appointment.
Frequently Asked Questions About Cystometry
Medical References
This article is based on peer-reviewed medical literature and international clinical guidelines:
- Schäfer W, Abrams P, Liao L, et al. Good Urodynamic Practices: Uroflowmetry, Filling Cystometry, and Pressure-Flow Studies. Neurourology and Urodynamics. 2002;21(3):261-274. doi:10.1002/nau.10066
- Rosier PFWM, Schaefer W, Lose G, et al. International Continence Society Good Urodynamic Practices and Terms 2016. Neurourology and Urodynamics. 2017;36(5):1243-1260. doi:10.1002/nau.23124
- American Urological Association. Adult Urodynamics: AUA/SUFU Guideline. 2023. www.auanet.org/guidelines
- European Association of Urology. EAU Guidelines on Urinary Incontinence in Adults. 2024. uroweb.org/guidelines
- National Institute for Health and Care Excellence. Urinary incontinence and pelvic organ prolapse in women: management (NICE Guideline NG123). 2019. www.nice.org.uk/guidance/ng123
- Abrams P, Cardozo L, Wagg A, Wein A, eds. Incontinence: 6th International Consultation on Incontinence. International Continence Society; 2017.
- Nitti VW. Pressure flow urodynamic studies: the gold standard for diagnosing bladder outlet obstruction. Reviews in Urology. 2005;7 Suppl 6:S14-S21.
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This article was written and reviewed by our medical editorial team, which includes board-certified specialists in urology and urodynamics.
Licensed physicians with expertise in urology and medical communication, trained to translate complex medical information into accessible content.
Board-certified urologists and urogynecologists who verify accuracy according to current evidence and clinical guidelines from ICS, AUA, and EAU.
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