Kidney stones are hard masses formed from crystallized minerals and salts within the urinary tract. These deposits, often starting in the kidney, travel through the tubes that carry urine toward the bladder. While a kidney stone rarely causes a complete loss of bladder control, its movement can disrupt normal urinary function. The resulting irritation often leads to intense urinary urgency, frequency, and involuntary leakage, categorized as urge or functional incontinence.
How Kidney Stones Affect Bladder Function
The kidney connects to the bladder via the ureter, a narrow tube. As a kidney stone passes down the ureter, it causes significant irritation to the tube’s lining. This irritation intensifies as the stone approaches the ureterovesical junction, where the ureter inserts into the bladder wall.
This area is particularly sensitive, and the presence of the stone creates inflammation that the bladder interprets as a signal that it is full. The bladder muscle begins to contract involuntarily in response to this false signal, causing a sudden and powerful urge to urinate. Individuals often experience a dramatic increase in how often they need to go, referred to as urinary frequency.
When the urge to void is sudden and overwhelming, it can be difficult to reach a restroom in time, leading to accidental urine loss. This functional incontinence results from the stone’s irritating effect on the lower urinary tract. The constant irritation and spasms of the bladder muscle cause these symptoms to persist until the stone passes or is removed.
Classic Symptoms of Kidney Stone Passage
Symptoms associated with a kidney stone moving through the ureter are often severe. The most recognized symptom is renal colic, an intense, fluctuating pain caused by the stone obstructing urine flow. This obstruction causes pressure to build up rapidly within the kidney.
The pain from renal colic is typically felt in the flank (the side and back area just below the ribs). As the stone travels lower toward the bladder, the pain may migrate to the abdomen, groin, or inner thigh. This pain is often accompanied by secondary symptoms, most notably nausea and vomiting.
Another indicator of stone passage is hematuria, or blood in the urine. The rough edges of the stone scrape against the lining of the urinary tract, causing small amounts of bleeding. This may cause the urine to appear pink, red, or brown, though sometimes the blood is only detectable through laboratory analysis.
Seeking Medical Diagnosis and Treatment
If you experience the sudden onset of severe flank pain, intense urinary urgency, or blood in your urine, seek immediate medical evaluation. A healthcare provider will use imaging tests to confirm the presence and location of the stone. A non-contrast computed tomography (CT) scan is the most common tool used to accurately locate the stone and determine its size.
A urinalysis is performed to check for signs of infection, blood, or crystals in the urine. For smaller stones, initial management involves pain control and hydration to encourage natural passage. Medications known as alpha-blockers may be prescribed to relax the muscle in the ureter, making stone passage easier and faster.
Stones larger than five millimeters or those causing a persistent blockage may require active intervention. Extracorporeal shock wave lithotripsy (ESWL) uses focused sound waves to break the stone into smaller fragments that can be passed. Alternatively, ureteroscopy involves inserting a thin, lighted scope through the urethra and bladder to directly remove or fragment the stone.