Bladder stones are hard masses of minerals that form inside the bladder when urine sits there too long or becomes too concentrated. They develop when dissolved minerals in urine crystallize and clump together, gradually growing into solid stones that can range from grain-of-sand tiny to golf-ball sized. About half of all bladder stones in adults are made of uric acid, while the rest consist of calcium oxalate, calcium phosphate, or other mineral combinations. Unlike kidney stones, which form higher up in the urinary tract, bladder stones specifically develop in the bladder itself, often because something is preventing it from emptying completely.
How Bladder Stones Form
The core problem behind most bladder stones is urinary stasis, meaning urine stays in the bladder longer than it should. When the bladder can’t fully empty, the leftover urine becomes increasingly concentrated. Minerals dissolved in that urine begin to crystallize, and those tiny crystals serve as a seed for further mineral deposits to build on. Over time, layers accumulate and a solid stone takes shape.
Infections can accelerate this process. Bacteria in the urinary tract alter the urine’s pH and change the concentration of citrate, a natural substance that normally helps prevent crystals from forming. When infection disrupts this balance, crystallization happens more easily. One specific type of stone, called a struvite stone (made of calcium, ammonium, and magnesium phosphate), only forms in the presence of infection.
Common Causes and Risk Factors
In men, an enlarged prostate is the most frequent trigger. The prostate surrounds the urethra just below the bladder, and when it grows, it can squeeze the urethra shut or push up into the bladder like a ball valve, blocking urine flow. Roughly 10% of men with an enlarged prostate develop bladder stones as a complication, though the link isn’t purely mechanical. Poor bladder emptying also invites urinary tract infections, which further promote stone formation.
People with nerve damage affecting the bladder face an especially high risk. After a spinal cord injury, the overall incidence of urinary stones is about 16.6%, and bladder stones account for the largest share. Male sex, a complete spinal injury, and catheter use (whether intermittent, indwelling, or external) are all independent risk factors. Catheters can introduce bacteria and act as a surface where crystals deposit.
Other conditions that prevent the bladder from emptying properly can also lead to stones. These include bladder surgery, radiation to the pelvic area, and chronic inflammation of the bladder wall. Foreign objects in the bladder, such as surgical sutures or migrated medical devices, sometimes serve as a nucleus for crystal buildup too.
Who Gets Bladder Stones
Bladder stones overwhelmingly affect men, reflecting the role prostate enlargement plays in their formation. Globally, men develop urinary stones at nearly twice the rate of women, with an incidence of about 1,857 per 100,000 people compared to 947 per 100,000 for women. The peak age is 50 to 59, when prostate growth tends to become clinically significant. In children, bladder stones are rare in developed countries but more common in parts of South Asia, the Middle East, and North Africa, often linked to dehydration and diets low in animal protein. Children’s stones tend to be calcium oxalate or calcium phosphate rather than uric acid.
Symptoms to Recognize
Small bladder stones sometimes cause no symptoms at all and are discovered incidentally on imaging done for another reason. When symptoms do appear, they typically include:
- Lower abdominal pain, often felt just above the pubic bone
- Pain or burning during urination
- Urinating more frequently than usual, including waking at night to go
- Blood in the urine, which may look pink, red, or dark brown
- Difficulty starting or maintaining a stream, or being unable to urinate at all
- Frequent urinary tract infections
A classic pattern is urine flow that suddenly stops mid-stream. This happens when the stone rolls over the bladder’s internal opening and temporarily blocks it. Shifting position or moving around can dislodge it and allow urine to flow again. Pain often worsens with physical activity or jarring movements because the stone bounces against the bladder wall.
How Bladder Stones Are Diagnosed
A CT scan is the gold standard. It picks up stones with over 95% sensitivity and can identify their size, number, and exact location. Ultrasound is a reasonable first step since it’s quick, widely available, and involves no radiation, but its sensitivity for detecting stones varies widely, from as low as 24% to as high as 93% depending on the operator and equipment. Pooled across studies, ultrasound catches about 45% of stones, meaning it misses more than half. If ultrasound results are inconclusive or symptoms persist, a CT scan is the next step.
A simple X-ray of the pelvis can sometimes reveal bladder stones, but only if they contain enough calcium to show up on film. Uric acid stones, which make up about half of adult bladder stones, are radiolucent, meaning they’re invisible on a standard X-ray.
Treatment Options
Very small bladder stones occasionally pass on their own if you increase your fluid intake enough to flush them out. But most bladder stones require a procedure because the underlying cause (typically incomplete bladder emptying) keeps the conditions ripe for the stone to grow rather than pass.
The most common procedure is cystolitholapaxy. A thin scope is passed through the urethra into the bladder, and the stone is broken apart using a laser, ultrasound probe, or mechanical device. The fragments are then washed out or suctioned away. Laser-based versions achieve complete stone clearance in nearly all cases, with one study reporting 100% clearance and another 89%. The procedure can often be done under local anesthesia. Most patients go home within one to three days, and a catheter placed during the procedure is typically removed within a few hours. You may notice small stone fragments passing during your first few trips to the bathroom afterward.
For very large stones, or when the urethra is too narrow to accommodate a scope, open or minimally invasive surgery through a small incision in the lower abdomen may be necessary. This is less common today but still used when needed. Importantly, treating only the stone without addressing the underlying cause (enlarged prostate, nerve damage, or another obstruction) leads to recurrence. Many patients undergo a prostate procedure at the same time as stone removal.
Dietary and Lifestyle Prevention
Drinking enough water is the single most effective way to prevent bladder stones from coming back. Six to eight glasses (8 ounces each) per day is the standard recommendation, though people in hot climates or those who exercise heavily need more. The goal is to keep urine dilute so minerals stay dissolved rather than crystallizing.
Beyond hydration, the best dietary approach depends on the type of stone you formed. Since uric acid stones are the most common in adults, reducing animal protein is often the first recommendation. Red meat, organ meats, shellfish, and eggs all increase uric acid levels in urine. Losing weight matters too, because excess body weight raises uric acid production.
For calcium-based stones, the key adjustments are reducing sodium intake (aim for under 2,300 mg per day) and getting calcium from food rather than supplements. This sounds counterintuitive, but dietary calcium actually binds to oxalate in the digestive tract, preventing it from reaching the kidneys and bladder. Low-oxalate, plant-based calcium sources like fortified cereals, juices, and certain vegetables are ideal. If your stones contained oxalate, limiting high-oxalate foods like spinach, rhubarb, nuts, and wheat bran can help.
The DASH diet, originally designed for blood pressure control, has also been shown to reduce the risk of urinary stones. It emphasizes fruits, vegetables, whole grains, and low-fat dairy while limiting sodium, red meat, and added sugars, hitting most of the dietary targets for stone prevention in a single eating pattern.
Recurrence and Long-Term Outlook
Bladder stones tend to come back if the underlying cause isn’t corrected. Someone whose prostate blocks urine flow will likely form new stones even after successful removal unless the obstruction is treated. Similarly, people who rely on catheters for bladder management face ongoing risk and benefit from regular monitoring. After treatment, follow-up imaging at around six months is typical to check for new stone formation. In studies tracking patients after laser stone removal, no recurrent stones developed within six months when the underlying condition was also addressed.