Bladder Stones (Bladder Calculi)

How bladder stones form

Normally the bladder empties almost completely. When urine stays behind, salts and minerals become concentrated and can crystallize into stones. Infection makes this more likely: some bacteria break down urea and make the urine alkaline, promoting struvite stones. Most bladder stones in adults are uric acid stones (often related to acidic urine) or struvite stones. Small kidney stones can also pass down into the bladder and grow larger if the bladder does not empty well.

Causes and risk factors

Incomplete bladder emptying

• Benign prostatic hyperplasia: an enlarged prostate blocking urine flow is the most common cause in men over 50
• Neurogenic bladder: from spinal cord injury, multiple sclerosis, diabetes or spina bifida
• Urethral stricture: a narrowing from scar tissue
• Cystocele: a prolapsed bladder in women
• Bladder diverticula: pouches in the bladder wall that trap urine

Foreign material

• long-term urinary catheters
• stitches, staples or mesh from previous surgery
• bladder augmentation surgery using bowel tissue

Other factors

• recurrent urinary tract infections
• dehydration and a diet high in purines (for uric acid stones)
• in children in some low-income countries, a low-protein diet and dehydration (endemic bladder stones)

Bladder stones are much more common in men than women.

Symptoms

Some stones cause no symptoms and are found on a scan. When symptoms occur:

• lower belly (suprapubic) pain or discomfort
• pain at the tip of the penis in men
• pain and burning when urinating
• frequent urination, especially at night
• a stream that stops suddenly, then restarts when you change position, as the stone blocks the bladder outlet
• blood in the urine, often at the end of urination
• cloudy or dark urine
• recurrent urinary tract infections
• symptoms that worsen with movement, jogging or jolting

Bladder stones vs kidney stones

Diagnosis

• Urine test for blood, infection and crystals
• Ultrasound of the bladder and kidneys, and a bladder scan to measure leftover urine
• CT scan (low-dose): the most accurate test for stone size and number
• X-ray: shows calcium-containing stones but may miss uric acid stones
• Cystoscopy: a camera through the urethra to see the stones and the bladder lining, also used to check for other problems such as tumors
• Blood tests: kidney function
• Prostate assessment and flow tests in men

Treatment

Removing the stones

• Transurethral cystolitholapaxy: the most common treatment. A cystoscope is passed through the urethra, and a laser or ultrasonic device breaks the stones into fragments, which are washed out. It is usually done under general or spinal anesthesia, often as a day case or with an overnight stay.
• Percutaneous cystolitholapaxy: through a small cut in the lower belly, for large stones or when the urethra is too narrow.
• Open surgery: for very large stones, or when prostate surgery is done at the same time.
• Dissolving: small uric acid stones can sometimes be dissolved by making the urine alkaline with medicine (potassium citrate), but this is less often successful than with kidney stones.

Treating the cause

Stones often return unless the underlying problem is fixed:

• prostate surgery (such as transurethral resection) or medicines for an enlarged prostate
• intermittent self-catheterization for a neurogenic bladder
• treating a stricture or prolapse
• regular catheter changes and good catheter care

Prevention

• drink enough fluids to keep urine pale, usually 2 to 3 liters a day unless told otherwise
• treat urinary infections promptly
• empty the bladder fully, using double voiding (urinate, wait a minute, try again)

Complications

Untreated bladder stones can cause recurrent infections, urinary retention, bladder wall irritation and, rarely, long-term inflammation linked to bladder cancer. Blockage can back pressure up to the kidneys.

Frequently asked questions

What causes bladder stones?

Bladder stones usually form when the bladder does not empty fully, so minerals in leftover urine crystallize. Common causes are an enlarged prostate, nerve damage affecting the bladder, a narrowed urethra, bladder prolapse, long-term catheters and recurrent infections.

What are the symptoms of bladder stones?

Symptoms include lower belly pain, pain at the tip of the penis, painful or frequent urination, a stream that stops and starts, blood in the urine, cloudy urine and repeated infections. Some people have no symptoms.

Can bladder stones pass on their own?

Small stones sometimes pass in the urine, especially if the bladder empties well. Most bladder stones in adults are too large to pass and form because of an emptying problem, so they usually need removal, and the cause needs treatment.

How are bladder stones removed?

Most are removed by cystolitholapaxy: a thin camera is passed through the urethra, and a laser or ultrasound breaks the stones into tiny pieces that are flushed out. Very large stones may need a small cut in the lower belly or open surgery.

Are bladder stones the same as kidney stones?

No. Kidney stones form in the kidneys and cause severe pain in the side and back. Bladder stones usually form in the bladder because urine is not emptied fully. A kidney stone that passes into the bladder can, however, grow into a bladder stone.