Kidney stones are common, affecting many individuals at some point in their lives. These hard deposits form within the kidneys, and while their presence can often go unnoticed initially, their movement through the urinary system frequently causes discomfort. A significant concern for many is whether these stones can pass on their own or become lodged, leading to further complications and requiring medical attention.
How Kidney Stones Pass
Kidney stones typically begin their journey in the kidney, which filters waste from the blood to produce urine. From the kidney, urine, along with any stones, travels down a narrow tube called the ureter. Each kidney has a ureter connecting it to the bladder, where urine is stored until expelled through the urethra.
Stone passage involves movement through the urinary tract. This journey relies on the natural muscular contractions of the ureter walls, a process known as peristalsis, which helps to propel the stone forward. The size and shape of the stone significantly influence its ability to navigate these pathways, as smooth, small stones generally pass more easily than larger, irregularly shaped ones.
Do 3mm Kidney Stones Get Stuck
A 3mm kidney stone is considered small with a high probability of spontaneous passage. Stones 4mm or smaller have a high passage rate, with 80-90% passing within one to two weeks. The average diameter of a human ureter, the tube connecting the kidney to the bladder, typically ranges from 3 to 4 millimeters, and it can distend to accommodate larger objects. This natural flexibility often allows smaller stones like those measuring 3mm to move through without intervention.
Despite their small size, 3mm stones can still get stuck due to individual anatomical variations or stone characteristics. Anatomical variations, such as narrower sections or kinks within the ureter, can impede passage. The ureter has three naturally constricted points, particularly at the ureterovesical junction where it enters the bladder, which can pose a challenge even for small stones. A stone’s specific shape also plays a role; a jagged or spiky surface might catch more easily than a smooth, rounded one. Swelling or inflammation within the ureter, often caused by the stone’s presence or movement, can further constrict the pathway and prevent even small stones from moving forward, leading to obstruction.
Recognizing a Stuck Kidney Stone
When a kidney stone becomes lodged, it can obstruct the flow of urine, leading to a range of noticeable symptoms. The most common symptom is renal colic: intense, wave-like pain originating in the flank or back, radiating to the abdomen or groin. This pain arises from the ureter’s attempts to push the stone along and the resulting pressure buildup behind the obstruction.
Other indicators of a stuck stone include changes in urination patterns, such as frequent urges to urinate, a burning sensation during urination, or difficulty passing urine. Nausea and vomiting are common due to severe pain. In some cases, blood may be present in the urine, either visible or microscopic, as the stone irritates the lining of the urinary tract.
When to Seek Help
Seek medical attention if kidney stone symptoms are severe, persist, or indicate a stuck stone. Immediate evaluation is needed for uncontrollable pain, persistent vomiting preventing fluid intake, or signs of infection. Fever and chills, especially with flank pain, can indicate a serious infection behind the obstruction, requiring urgent intervention.
An obstructed stone, especially if infected, can lead to serious conditions like urosepsis, a life-threatening bloodstream infection. Prolonged obstruction can also cause hydronephrosis (kidney swelling from urine backup), potentially leading to permanent kidney damage. Healthcare professionals assess the situation with imaging tests and may recommend interventions. These range from pain management and observation for spontaneous passage to procedures like ureteroscopy or lithotripsy if the stone fails to pass or causes complications.