Bladder stones can form both directly in the bladder and in the kidneys. From there, they enter the bladder through the ureters and are therefore also referred to as secondary bladder stones.
Bladder stones are caused by special salts in the urine. Normally they are dissolved in the urine and are excreted. However, if the concentration of salt is too high, they crystallize and form small grains, so-called concretions. New layers of crystallized salt can form on top. As a result, they grow and can reach a size that causes discomfort.

Bladder stones form from crystallized salts in the urine © losonsky | AdobeStock
Bladder stones are differentiated according to their chemical composition. The classification of bladder stones is important for determining the cause, diagnosis and treatment. The stones consist of different salts:
- Calcium oxalate stones (about 75 percent of all urinary stones)
- Struvite stones made of magnesium ammonium phosphate (about 10 percent)
- Urate stones made of uric acid (about 5 percent)
- Calcium phosphate stones (about 5 percent)
- Cystine stones (rare)
- Xanthine stones (rare)
In many cases, the body flushes out the bladder stones on its own. They are then harmless and cause no symptoms.
However, it can happen that the stones block the exit to the urethra and thus also impede the flow of urine. They can also become so large that they can no longer be excreted in the urine.
In both cases, the following symptoms may occur:
- Stakkatomiktion (repeatedly interrupted urine flow),
- frequent urge to urinate with only small amounts of urine,
- foreign body sensation,
- Pain at the end of urination (in men sometimes extending to the tip of the penis),
- abdominal pain,
- bladder cramps,
- blood in the urine,
- Irritation of the mucous membrane and associated inflammation of the bladder,
- Urinary retention (urine can no longer be passed).
There are many possible causes for the formation of bladder stones. Often several factors come together in the formation of urinary stones. The factors involved in the formation of bladder stones include
- Outflow obstruction caused by disease (for example, prostate enlargement),
- urinary tract infection,
- an unfavorable diet high in animal fats and proteins and foods containing oxalic acid (for example nuts, rhubarb and coffee),
- low fluid intake,
- unbalanced diet with lots of meat and dairy products,
- increased supply of vitamin D3,
- lack of vitamins B6 and A,
- Foreign bodies in the bladder (e.g. a bladder catheter or surgical sutures),
- Osteoporosis and the associated greater release of calcium into the blood,
- oversupply of magnesium.
If bladder stones are suspected, you should consult a urologist, a specialist in diseases of the urinary tract.
They will first take a medical history. They will ask you about your symptoms and your medical history. They will then carry out a physical examination. They will listen to your abdomen with a stethoscope and carefully palpate it. The patient's blood and urine will also be examined in the laboratory.
Imaging procedures may also be used, such as an X-ray or ultrasound examination. With these procedures, however, only calcium-containing bladder stones are visible on the image, the other types are radiolucent.
Another option is computer tomography, also known as CT. This enables the doctor to detect all types of bladder stones.
A cystoscopy (bladder endoscopy) can also provide information about any bladder stones present. A rod-like device with a camera is inserted into the bladder. The advantage of this is that the doctor can also identify other possible causes for the blockage of urine flow.
The treatment for bladder stones depends on the size and location of the stones. In some cases, targeted removal is necessary, in others they can be flushed out on their own.
Certain medications and an increase in the amount of fluid drunk can help to flush them out. Painkillers are used to relieve possible pain when the bladder stones pass.
Sometimes it is possible to treat the stones with a so-called chemolitholysis. This involves dissolving or reducing the size of the bladder stones through a chemical reaction so that they can be flushed out.
In some cases, it is necessary to remove the stones surgically. The surgeon removes smaller stones directly during cystoscopy or crushes them with forceps.
Open surgery is rarely performed today. However, it may be necessary, for example, if the doctor cannot get into the bladder during cystoscopy because it is blocked by the stone.
Extracorporeal shock wave lithotripsy(ESWL) is now frequently used to treat stones. This uses pressure waves to break the bladder stones into smaller stones, which can then be excreted in the urine.