Bladder / Ureter Calculus
A bladder or ureter calculus is a solid crystalline deposit (stone) located within the ureter or bladder. Most of these stones originate in the kidney and travel down the urinary tract, though bladder stones can also form directly in the bladder in the setting of urinary stasis or foreign bodies. Ureteral stones commonly cause severe flank or back pain (renal colic) and blood in the urine, and can lead to obstruction and infection if not managed appropriately. Bladder stones may cause pain, urinary symptoms, blood in the urine, or, in some cases, no symptoms. Evaluation combines imaging (particularly non-contrast CT for ureteral stones and ultrasound or CT for bladder stones), urine studies, and clinical assessment.
What is it?
Urinary stones (also called urinary calculi or urolithiasis) are solid crystalline deposits that form from substances dissolved in the urine. They can form in the kidney, ureter, or bladder. Stones vary widely in size, from tiny fragments smaller than a grain of sand to large stones that fill portions of the collecting system. They also vary in composition; the most common types are calcium oxalate (the majority of stones), calcium phosphate, uric acid, struvite (associated with infection), and cystine (from an inherited condition called cystinuria). The composition affects how stones appear on imaging, how they respond to treatment, and what preventive strategies are recommended.
Ureteral stones typically originate in the kidney and pass into the ureter, where they can lodge—particularly at natural narrowings such as the ureteropelvic junction (where the renal pelvis meets the ureter), where the ureter crosses over the iliac vessels in the pelvis, or at the ureterovesical junction (where the ureter enters the bladder). Small stones (typically less than 5 mm) often pass through the ureter and out through the bladder on their own with appropriate pain control and hydration. Larger stones (particularly those greater than about 5–7 mm) are less likely to pass spontaneously and often require intervention. The pain associated with a passing ureteral stone—renal colic—can be severe and comes in waves as the ureter contracts around the stone.
Bladder stones can develop in two main ways. In some patients, particularly older men with bladder outlet obstruction (most often from an enlarged prostate), incomplete bladder emptying leads to urine stasis and the formation of stones directly in the bladder. This mechanism is by far the most common cause of bladder stones in adults in developed countries. Bladder stones can also result from stones that have passed down from the kidney and grown in the bladder, from foreign bodies (such as sutures from prior surgery, migrated ureteral stents, or, less commonly, catheter fragments), or from long-term indwelling catheters. In children, bladder stones are much less common in developed countries but remain more frequent in some regions of the world, particularly in the context of specific dietary factors.
Multiple risk factors contribute to stone formation. Dehydration is one of the most important modifiable factors, as it concentrates the urine and increases the likelihood of crystal formation. Dietary factors—including high intake of animal protein, sodium, and certain foods high in oxalate (spinach, nuts, chocolate, and others)—can increase risk. Certain medical conditions—including hyperparathyroidism, gout, diabetes, obesity, inflammatory bowel disease, previous bariatric surgery (particularly Roux-en-Y gastric bypass), certain kidney conditions, and cystinuria—increase risk. Some medications also increase the risk of stones. A personal or family history of stones significantly increases the likelihood of developing further stones.
Symptoms of a ureteral stone typically develop suddenly. Renal colic—severe, colicky pain in the flank or back that radiates to the abdomen, groin, testicle, or labia—is the classic presentation. Patients typically cannot find a comfortable position and often pace or move restlessly (in contrast to conditions like appendicitis, where patients tend to stay still). Nausea and vomiting are common. Blood in the urine (visible or microscopic) is present in most patients. Symptoms of urinary tract infection may be present, and the combination of stone obstruction and infection is a urologic emergency because of the risk of sepsis.
Symptoms of a bladder stone vary. Some patients experience pain in the lower abdomen (particularly with activity or bladder filling), urinary symptoms including frequency, urgency, difficulty starting the urine stream, weak stream, sensation of incomplete emptying, painful urination, and interrupted urination (as the stone temporarily blocks the bladder outlet). Blood in the urine is common. Recurrent urinary tract infections may occur. Some patients—particularly with small bladder stones or in the setting of long-standing bladder outlet obstruction—have few symptoms or attribute their symptoms to their underlying obstruction rather than to stones.
Diagnosis is based on imaging and laboratory testing. Non-contrast CT (often called CT KUB, for kidneys, ureters, bladder) is the primary imaging test for suspected ureteral stones and is highly sensitive, detecting the vast majority of stones and providing information about their size, location, and any obstruction. It can also identify secondary findings such as hydronephrosis and perinephric stranding that support the diagnosis. Ultrasound is often used first in pregnant women (to avoid radiation) and in children, and can identify hydronephrosis and larger stones, though it is less sensitive than CT for smaller ureteral stones. Abdominal X-ray (KUB) can identify radiopaque stones (such as calcium-containing stones) but misses radiolucent stones (such as uric acid stones). For bladder stones, both CT and ultrasound are useful, and stones are often visible on both.
Laboratory testing typically includes urinalysis (usually shows blood, often shows crystals, and may show signs of infection), urine culture (to identify infection), complete blood count, kidney function, electrolytes, and, in selected patients, uric acid and calcium levels. Metabolic evaluation with 24-hour urine studies is recommended for patients with recurrent stones or specific risk factors, and can identify metabolic abnormalities (such as high urine calcium, low urine citrate, or high urine oxalate) that guide preventive strategies. Stone analysis when a stone is retrieved (either passed spontaneously or removed surgically) provides critical information about the stone type.
Evaluation for underlying causes of bladder stones—particularly bladder outlet obstruction from an enlarged prostate in men—is important. This may include urinary flow studies, ultrasound assessment of post-void residual urine, and cystoscopy.
Important to Know
Management of urinary stones is highly individualized based on the location, size, composition (when known), symptoms, presence of infection, kidney function, and patient factors. Care is typically coordinated by emergency medicine clinicians (in acute presentations), urologists, and, in specific circumstances, nephrologists, radiologists, and other specialists.
For ureteral stones, the initial priority is pain control and evaluation for complications. Nonsteroidal anti-inflammatory drugs (NSAIDs, such as ketorolac or ibuprofen) are effective for renal colic and are often used as first-line pain treatment when appropriate. Opioids may be added or used when NSAIDs are contraindicated or inadequate. Adequate hydration is important. Antiemetics may be needed for nausea and vomiting.
Small ureteral stones (typically less than 5 mm) often pass spontaneously with time. Observation with pain control, hydration, and, in some cases, medical expulsive therapy (medications such as tamsulosin that may help facilitate stone passage) is a reasonable approach in patients without infection, significant obstruction, or intractable pain. The evidence for medical expulsive therapy is mixed, with more benefit generally seen for larger distal ureteral stones. Patients are typically monitored with imaging follow-up and clinical assessment.
For ureteral stones that do not pass, are too large to pass, or that require urgent intervention, several treatment options are available. Ureteroscopy with laser lithotripsy is a common and highly effective approach in which a thin scope is passed up the ureter and a laser is used to fragment the stone. Fragments are then removed or allowed to pass. Shock wave lithotripsy (SWL) uses external focused shock waves to fragment the stone into smaller pieces that can pass on their own; it is well-suited for many kidney and upper ureteral stones. Percutaneous approaches (such as percutaneous nephrolithotomy) are typically reserved for larger stones located in the kidney rather than the ureter but may be used in specific circumstances. Ureteral stent placement or percutaneous nephrostomy is used in specific situations, such as to relieve obstruction associated with infection, in patients with severe pain not controlled by other means, or when planning definitive treatment.
The combination of stone obstruction and infection is a urologic emergency. Prompt drainage (typically with a ureteral stent or percutaneous nephrostomy) and antibiotics are essential to prevent sepsis. Definitive stone treatment is usually deferred until infection is controlled.
For bladder stones, cystolitholapaxy (endoscopic breakup of the stone through a cystoscope, using laser, mechanical, or other energy sources) is the most common treatment. Larger stones may require multiple sessions or, less commonly, open or laparoscopic bladder surgery. Treatment of underlying bladder outlet obstruction (such as with medications or surgery for an enlarged prostate) is essential to prevent recurrence.
For patients with a first stone episode, evaluation for underlying causes and preventive measures is important. Basic assessment includes stone analysis (when possible), urinalysis, and metabolic evaluation with a 24-hour urine study in appropriate patients. Preventive strategies include increased fluid intake (aiming for at least 2 to 2.5 liters of urine output per day for most patients), dietary modifications tailored to stone type and metabolic findings (such as reduced sodium and animal protein intake, adequate but not excessive calcium intake from food, and reduced intake of oxalate-rich foods for calcium oxalate stone formers), and, in selected patients, medications (such as thiazide diuretics for hypercalciuria, potassium citrate to raise urinary citrate and pH, allopurinol for uric acid stones or hyperuricosuria).
For patients with recurrent stones, more detailed metabolic evaluation with 24-hour urine studies and, in some cases, more targeted testing, along with individualized preventive strategies, is important. Follow-up is often coordinated by urologists or nephrologists with expertise in stone prevention.
For pregnant patients with stones, management is individualized. Most stones can be managed conservatively during pregnancy with hydration and pain control. When intervention is needed, ureteroscopy or ureteral stent placement is typically preferred, with attention to fetal safety. Shock wave lithotripsy is generally avoided during pregnancy. Coordination with obstetrics and, when appropriate, maternal-fetal medicine is important.
For patients with certain systemic conditions (such as cystinuria or primary hyperoxaluria), specialized care and preventive strategies are important, and coordination with nephrology and, in some cases, genetics is beneficial.
Care during and after treatment includes monitoring for complications (such as bleeding, infection, ureteral injury, or persistent obstruction), pain control, and follow-up imaging to confirm stone clearance.
Care is typically coordinated by urologists and, when needed, nephrologists, primary care clinicians, and other specialists. Imaging and laboratory findings are interpreted alongside the patient’s symptoms, examination, past medical history, and broader clinical context rather than in isolation.
Patient education plays an important role. Understanding the diagnosis, the specific stone type when known, the rationale for the treatment plan, the importance of preventive measures (particularly hydration and dietary modifications), warning signs of recurrent stones or complications, and, when relevant, treatment of underlying conditions such as bladder outlet obstruction all contribute to better outcomes.
Red flag symptoms include severe flank or back pain not controlled by medications, high fever with chills (which combined with obstruction is a urologic emergency), signs of sepsis (severe illness, low blood pressure, rapid heart rate, confusion), significant decrease or absence of urine output (particularly if both kidneys may be affected or in a solitary kidney), significant blood in the urine with clots or difficulty urinating, severe nausea and vomiting with dehydration, severe abdominal pain, sudden inability to urinate, or rapid clinical deterioration. These warrant prompt or urgent medical evaluation, as they may indicate obstructed infection, severe obstruction, or other serious complications.