Bladder hydrodistension
While you are asleep, a doctor looks inside the bladder with a camera and gently stretches it by filling it with water for a short time. It helps diagnose interstitial cystitis, finds and treats Hunner lesions, and eases symptoms for some people.
Also called hydrodistention, bladder stretching, bladder stretch under anesthesia, cystoscopy with hydrodistension, cysto and hydro, interstitial cystitis procedure, IC bladder stretch, painful bladder syndrome procedure
- Where
- Outpatient surgery center or hospital operating room
- Anesthesia
- General anesthesia or spinal anesthesia (stretching the bladder while awake would be too painful)
- Time in the room
- About 20 to 45 minutes
- Hospital stay
- Same day
- Back to normal
- A few days to 2 weeks. Some people have a flare of symptoms before they feel better.
- Back to work
- Usually 1 to 3 days, longer if you have a flare
Overview
Interstitial cystitis, also called bladder pain syndrome (IC/BPS), causes pain, pressure, or discomfort felt in the bladder, along with urgency and frequent urination, without an infection or other clear cause. Hydrodistension is a procedure done while you are asleep. The doctor looks inside the bladder with a cystoscope (a thin camera passed through the urethra, the tube that carries urine out) and then gently fills the bladder with sterile water under low pressure for a short time.
It does three things. It lets the doctor see the bladder lining and look for Hunner lesions, red inflamed patches found in a smaller group of people with IC/BPS. It measures how much the bladder holds when you are asleep and relaxed. And for some people, the stretch itself eases symptoms for a while.
If a Hunner lesion is found, the doctor can treat it in the same procedure, either by sealing it with an electric current or laser (fulguration) or by injecting a steroid medicine called triamcinolone into it. The AUA guideline on IC/BPS recommends treating Hunner lesions this way, and it often gives meaningful relief.
The AUA guideline supports only short, low-pressure stretching. Long stretches at high pressure are no longer recommended because they can scar and shrink the bladder. Hydrodistension is one tool among many, and most people with IC/BPS do best with several treatments together.
The parts of your body involved
The bladder lining is covered by a protective layer that normally keeps urine from irritating the wall underneath. In IC/BPS, the lining and the nerves of the bladder wall seem to become sensitive, so filling feels painful instead of simply full. In some people the lining has Hunner lesions: well-defined red, inflamed areas with small blood vessels running toward a pale center, which may crack and bleed when the bladder is stretched. After stretching, many bladders show glomerulations, tiny pinpoint bleeds in the lining. These are common in IC/BPS but are also seen in people without it.
- Bladder lining
The inner surface of the bladder (urothelium). It normally acts as a protective barrier against urine.
- Bladder muscle
The muscle layer (detrusor) that stretches as the bladder fills and squeezes to empty it.
- Hunner lesion
A red, inflamed patch on the lining found in a minority of people with IC/BPS. It responds to targeted treatment.
- Glomerulations
Pinpoint bleeds that appear in the lining after stretching.
- Urethra
The tube that carries urine out of the body. The scope passes through it.
- Pelvic floor muscles
The muscles under the bladder. In IC/BPS they are often tight and tender, which adds to the pain.
Why it’s done
Your urologist may suggest hydrodistension to look for Hunner lesions, to rule out other problems, or to try for symptom relief when first-line treatments have not been enough. Hunner lesions are important to find, because they respond to targeted treatment in a way that other forms of IC/BPS do not.
- Looking for Hunner lesions
Especially when symptoms are severe, the bladder seems to hold very little, or you are older, which are features that make Hunner lesions more likely.
- Ruling out other causes
Bladder tumors, a flat early cancer called carcinoma in situ, stones, and other problems can mimic IC/BPS. A small tissue sample (biopsy) can be taken if anything looks unusual.
- Treating Hunner lesions
Lesions can be sealed or injected with steroid in the same procedure.
- Short-term symptom relief
For some people, the stretch eases pain and frequency for weeks to months.
- Measuring bladder capacity
How much the bladder holds while you are asleep helps your doctor plan further treatment.
Other options
- Self-care and diet changes
Avoiding personal trigger foods and drinks (often coffee, alcohol, citrus, tomatoes, spicy foods, artificial sweeteners, and carbonated drinks), managing stress, and using heat or cold on the lower belly or perineum. The AUA lists these as first steps for everyone.
- Pelvic floor physical therapy
Hands-on therapy by a trained physical therapist to relax tight, tender pelvic floor muscles. Strengthening exercises such as Kegels are usually avoided in IC/BPS.
- Medicines by mouth or in the bladder
Pills such as amitriptyline, cimetidine, hydroxyzine, and pentosan polysulfate (which needs regular eye exams because it can damage the retina). Medicines can also be placed in the bladder through a catheter, such as DMSO or mixtures of heparin and lidocaine.
- Bladder Botox injections
Injections into the bladder wall may help some people with IC/BPS whose symptoms continue, with a small risk of needing a catheter.
- Sacral neuromodulation
A trial of nerve stimulation with a small implanted device may help some people with urgency and frequency.
- Major surgery
Rarely, for a small, scarred bladder with severe symptoms after all other treatments, surgery to enlarge, bypass, or remove the bladder is considered.
Getting ready
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Weeks before
The week before
The day before
The morning of
In the operating room, step by step
Press play or pick a step. Each drawing shows what your surgeon is doing at that moment. Your team may do some steps differently.
1. Anesthesia and positioning
You go to sleep with general anesthesia, or the lower body is numbed with a spinal. You lie on your back with your legs in padded stirrups, and the genital area is cleaned and draped.
After the operation
Right afterward
- Recovery room
You wake up in the recovery area and rest for about 1 to 2 hours.
- First urination
Expect burning, urgency, and pink urine. The nurses make sure you can urinate before you leave.
- Pain relief
You may get a urinary pain reliever (phenazopyridine, which turns urine orange), a bladder antispasmodic, and pain medicine.
- Going home
Someone must drive you home. Have an adult stay with you the first night.
At home
- Pain and flares
Some people have more pain, urgency, and frequency for a few days, occasionally up to 2 weeks, before they improve. Use your pain plan, heat, and rest.
- Blood in the urine
Pink urine is common for 1 to 3 days, longer if a lesion was treated.
- Fluids and food
Drink enough to keep urine pale, and stay away from your trigger foods and drinks while the bladder settles.
- Heat and baths
A warm pack on the lower belly or a warm sitz bath can ease spasms and pain.
- Activity
Rest the first day, then return to light activity. Most people are back to normal within a few days.
- Driving
Do not drive for 24 hours after anesthesia, or while taking opioid pain medicine.
- Showering
You can shower the next day.
- Sex
Wait until bleeding and burning settle, often about a week.
- Work
Most people return in 1 to 3 days, longer if they flare.
Recovery timeline
- Day 0Procedure day
You go home a few hours after the procedure.
- Days 1 to 3Burning and pink urine
Frequency, burning, and pink urine. Some people flare.
- Week 1 to 2Settling
Any flare usually settles over this time.
- Weeks 2 to 4Seeing the effect
If the stretch or lesion treatment is going to help, improvement usually shows by now.
- Weeks 4 to 6Follow-up visit
Your doctor reviews findings, any biopsy result, and your symptoms, and plans next steps.
- Months 2 to 6How long it lasts
Relief from the stretch alone often fades over weeks to months. Relief after treating Hunner lesions often lasts longer.
- Long termOngoing care
IC/BPS is usually managed with several treatments together. Hunner lesions can come back and can be treated again.
What it feels like
People with IC/BPS often arrive tired of pain and of tests that come back normal. Many feel relief simply when the doctor sees something, or confirms that nothing dangerous is there. The first few days afterward can be rough, with more burning and urgency, before things settle.
The night before
Worry that the procedure will make the pain worse, and dread of another test that shows nothing.
What helpsHave your pain plan written down and your medicines at home before the procedure.
Waking up
Burning, pressure, and a strong urge to urinate.
What helpsTell the nurse. Medicine, a warm pack, and time help.
The first urination
Burning, pink urine, sometimes small clots. It can be frightening.
What helpsDrink water and use the urinary pain reliever if prescribed. It improves each day.
The flare
Some people feel worse for days to 2 weeks and wonder if it was a mistake.
What helpsKnow that this is common and usually passes. Rest, use heat, and call your team if the pain is not controlled.
Hearing the results
If a Hunner lesion was found, many feel validated and hopeful. If none was found, some feel let down.
What helpsMost people with IC/BPS do not have Hunner lesions. Your diagnosis is still real, and many treatments remain.
When relief comes
Fewer trips and less pain, sometimes for the first time in years.
What helpsUse the better weeks to start or continue physical therapy and self-care, which can extend the benefit.
If relief fades
Frustration and fatigue.
What helpsTalk with your doctor about repeating the procedure, if it helped before, or adding other treatments.
How well it works
Hydrodistension helps some people, and how much varies widely. Some feel better for weeks to a few months; others notice little change. People with Hunner lesions often get clearer relief after the lesions are treated, sometimes lasting many months, and treatment can be repeated if lesions return.
- What the doctor saw
Whether Hunner lesions were present, how much the bladder held under anesthesia, and any biopsy result.
- Symptom questionnaire
Comparing your symptom scores before and after shows how much changed.
- Your diary
Fewer trips by day and night, and less pain on a 0 to 10 scale.
- Next steps
The findings guide which treatments to use next.
Risks
Every operation has risks. These are the ones people ask about most, with honest odds where good numbers exist. Your surgeon’s own results matter more than averages.
Common
Expected for a few days.
More pain and urgency for a few days, occasionally up to 2 weeks.
The stretch does not help everyone, and relief often fades with time.
Less common
Burning, fever, or cloudy urine starting a few days later.
After anesthesia, some people cannot empty the bladder for a short time and need a catheter for a day or so.
More likely after a Hunner lesion is treated.
Sore throat, nausea, or grogginess for a day.
Rare
A tear in the bladder wall from stretching. Rare with low-pressure filling. It may need a catheter for a while or, uncommonly, surgery.
Linked to long, high-pressure stretching, which is no longer recommended.
Very rare in healthy people.
Call your care team or go to the emergency room if
- Fever of 101°F (38.3°C) or higher, or shaking chills
- You cannot urinate, or only dribble, and your lower belly feels full or tight
- Thick blood, clots, or urine that looks like ketchup
- Severe belly pain that keeps getting worse, or a swollen, hard belly
- Pain that is not controlled by the medicine you were given
- Vomiting that keeps you from drinking fluids
- Burning, fever, or cloudy urine starting several days after the procedure (possible infection)
Questions to ask your surgeon
- Why do you recommend hydrodistension for me now?
- Will you use low pressure and a short stretch?
- If you find a Hunner lesion, will you seal it, inject it with steroid, or both?
- Will you take a biopsy? Why?
- Will you leave any medicine in my bladder at the end?
- What should I do if I have a flare afterward?
- When will I hear the results?
- If it helps, could I repeat it later?
- What other treatments should I start alongside it?
- Should I see a pelvic floor physical therapist?
Words you may hear
- IC/BPS
- Interstitial cystitis / bladder pain syndrome: bladder pain or pressure with urgency and frequency, without infection or another clear cause.
- Hydrodistension
- Gently stretching the bladder by filling it with water while you are asleep.
- Cystoscope
- A thin camera tube passed through the urethra to look inside the bladder.
- Hunner lesion
- A red, inflamed patch on the bladder lining found in some people with IC/BPS.
- Fulguration
- Sealing tissue with an electric current or laser.
- Triamcinolone
- A steroid medicine that reduces inflammation, sometimes injected into Hunner lesions.
- Glomerulations
- Pinpoint bleeds in the bladder lining after stretching.
- Bladder capacity
- How much the bladder holds. Measured under anesthesia during this procedure.
- Urothelium
- The lining of the bladder.
- Flare
- A temporary worsening of symptoms.
- Biopsy
- A small tissue sample checked under a microscope.
- Instillation
- Placing medicine directly into the bladder through a catheter.
- Pelvic floor physical therapy
- Hands-on treatment by a specially trained physical therapist to relax and retrain pelvic muscles.
Common questions
Will this cure my IC/BPS?
There is no single cure for IC/BPS. Hydrodistension can help with diagnosis and may ease symptoms for a while, and treating Hunner lesions can give longer relief. Most people need a combination of treatments.
Why do I need to be asleep?
Stretching the bladder to its full size would be very painful while awake. Anesthesia also lets the doctor measure your true bladder capacity.
Why do I feel worse afterward?
Stretching irritates the bladder for a few days. A flare is common and usually settles within 2 weeks.
What is a Hunner lesion, and why does it matter?
It is an inflamed patch on the bladder lining found in a minority of people with IC/BPS. Finding one matters because sealing or injecting it often helps much more than other treatments do.
Do glomerulations prove I have IC/BPS?
No. They are common in IC/BPS but also appear in people without it. Your diagnosis is based mainly on your symptoms and on ruling out other causes.
Can it be repeated?
Yes, if it helped before. Hunner lesions often come back and can be treated again.
Should I change my diet?
Many people find certain foods and drinks make symptoms worse. An elimination diet, removing likely triggers and adding them back one at a time, helps you find your own.
Sources this page draws on
- American Urological Association, Diagnosis and Treatment of Interstitial Cystitis/Bladder Pain Syndrome (2022)
- European Association of Urology, EAU Guidelines on Chronic Pelvic Pain
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Interstitial Cystitis (Painful Bladder Syndrome)
- Urology Care Foundation, Interstitial Cystitis (IC)/Bladder Pain Syndrome
- Interstitial Cystitis Association, Patient information on IC/BPS diagnosis and treatment
Written November 2026. This page explains what usually happens. It is not medical advice and does not replace a conversation with your own surgeon, whose plan for you comes first.