Kidney stones are solid, pebble-like formations that develop in the kidneys, made from minerals and salts found in urine. These hard deposits vary in size, from a grain of sand to larger than a golf ball. While they can remain in the kidney without issues, their movement through the urinary tract can cause significant discomfort and pain. Understanding their progression helps navigate this challenging experience.
How Kidney Stones Form and Begin to Move
Kidney stones typically form in the kidneys due to an imbalance in urine’s chemical composition. This often occurs with excessive crystal-forming substances, such as calcium, oxalate, uric acid, cystine, or phosphate, and insufficient fluid to dilute them. Common factors include chronic dehydration, diets high in sodium, added sugars, or animal protein, and genetic predispositions. Certain medical conditions, like gout or metabolic syndromes, also increase risk.
Once formed, a kidney stone can stay in the kidney without symptoms. If it dislodges and begins to move, it enters the ureter, part of the urinary tract. This initial movement might be imperceptible for smaller stones, or cause mild, intermittent discomfort or a dull ache in the flank or lower back. This sensation arises as the kidney attempts to push the stone along.
The Painful Ureteral Journey
The most challenging phase begins when a kidney stone enters the ureter, the narrow tube connecting the kidney to the bladder. This passage often causes intense, fluctuating pain known as renal colic. The pain typically starts suddenly in the side and back, below the ribs, often radiating to the lower abdomen and groin. This severe, wave-like pain occurs as the ureter contracts to push the stone, and if lodged, it can block urine flow, causing pressure and swelling in the kidney.
Accompanying the pain, individuals frequently experience nausea and vomiting. Blood in the urine (hematuria) is also common, resulting from the stone scraping against the ureteral lining. Urination may become more frequent, urgent, or painful, and the urine might appear cloudy or have a foul odor. Stones larger than 5 millimeters are less likely to pass spontaneously and are more prone to causing significant symptoms and blockages. Medical interventions often focus on pain management using strong pain relievers, and sometimes alpha-blockers are prescribed to relax ureteral muscles, aiding passage.
Reaching the Bladder and Final Passage
As the kidney stone enters the bladder, the severe, colicky pain typically subsides significantly. Individuals may still experience pressure or increased urinary urgency. The stone’s presence in the bladder can irritate the bladder lining, leading to a persistent urge to urinate more frequently.
The final act involves its expulsion from the bladder through the urethra during urination. This process is generally less painful than the ureteral journey, as the urethra is wider and shorter than the ureter. However, a brief, sharp sensation or burning may occur as the stone exits the body. In some instances, a stone might temporarily become lodged at the entrance of the urethra, causing a brief blockage of urine flow before it eventually passes.
What Happens After the Stone Passes
After the kidney stone has passed, it is important to collect it. Healthcare providers often advise straining urine to capture the stone, as its analysis provides crucial information about its composition. This analysis helps determine the type of stone, such as calcium oxalate or uric acid, which is essential for guiding future prevention strategies tailored to the individual’s specific stone type.
A follow-up appointment with a healthcare provider is recommended after stone passage. This visit allows for confirmation of complete stone passage, assessment for any residual urinary tract issues, and discussion of measures to prevent future stone formation. Prevention strategies are personalized and often involve dietary adjustments and increased fluid intake based on the stone’s analysis.