Kidney stones are small, hardened deposits of mineral and salt that form inside the kidneys. These structures can cause intense discomfort as they travel from the kidney through the narrow tubes of the urinary tract and into the bladder. Many people experiencing this pain wonder if they can successfully pass the stone without medical intervention. The answer is frequently yes, but self-passage depends on the stone’s physical characteristics and the patient’s condition.
Factors Determining Natural Passage
The size of the stone is the single most important predictor of whether it will pass naturally. Stones 4 millimeters (mm) or less have the highest spontaneous passage rate (81% to 98% chance of passing). This size is roughly equivalent to a grain of sand, and these smaller stones often pass relatively quickly, sometimes in a matter of days or weeks.
The likelihood of self-passage drops significantly for medium-sized stones, which range from 5 mm to 10 mm in diameter. A 5 mm stone, about the size of a match head, has a spontaneous passage rate of around 65%, which decreases sharply for stones 6 mm or larger. Stones greater than 10 mm, comparable to a small pea, rarely pass without some form of surgical or medical assistance.
The stone’s location within the urinary tract also strongly influences passage success and time. Stones that have already traveled down the ureter and are closer to the bladder, known as the distal or lower ureter, are much more likely to pass. This is because the lower ureter is wider and the stone is near the end of its journey. Stones lodged higher up, near the kidney, have a lower passage rate and typically take longer to exit the body.
Finally, the composition and shape of the stone can play a minor role in its movement. While size remains the primary factor, smooth stones may move more easily than those with jagged edges, which can catch on the lining of the ureter. Determining the stone’s type (e.g., calcium oxalate or uric acid) is important for future prevention, making stone capture a necessary step.
Self-Management Techniques to Aid Passage
If a medical professional determines a stone is small enough to pass, several self-management techniques can facilitate its movement. The primary strategy involves significantly increasing fluid intake to generate a high volume of urine flow. Drinking 2 to 3 liters of water per day is generally recommended to help flush the stone down the urinary tract.
Urine color serves as a simple indicator of hydration, which should be pale yellow to nearly clear. Some people find that adding fresh lemon juice to their water can be beneficial, as it contains citrate, which may help break down calcium deposits and slow the growth of certain stone types. Maintaining an active lifestyle and moving around can also use gravity and activity to encourage the stone’s movement through the ureter.
Pain management is necessary during passage, as renal colic can be severe. Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, manage the pain and reduce the swelling caused by the stone. A doctor may prescribe an alpha-blocker medication, such as tamsulosin, to relax the muscles in the ureter. This relaxation can widen the ureter’s passage, which significantly improves the stone expulsion rate, particularly for stones between 5 mm and 10 mm.
Patients attempting to pass a stone at home must also strain their urine using a specialized strainer or fine mesh. This allows for the collection of the stone fragment once it exits the body. Analyzing the stone’s composition is necessary for the doctor to recommend specific dietary or medication changes aimed at preventing future occurrences.
Warning Signs Requiring Emergency Care
While many small stones pass successfully, certain symptoms signal a complication or medical emergency requiring immediate care. The combination of severe pain and a fever, generally defined as a temperature above 101.5°F, indicates a possible infection in the kidney. This condition, known as pyelonephritis or an infected obstructed kidney, is an emergency because the stone traps bacteria-filled urine, which can lead to sepsis.
Intractable pain that cannot be managed with prescribed or over-the-counter medication is another serious warning sign. If the pain is unrelenting or severe enough to cause persistent nausea and vomiting, the patient risks dehydration and may require stronger pain relief administered in a hospital setting. Persistent vomiting can prevent the patient from staying adequately hydrated, which is necessary for stone passage.
A complete or near-complete blockage of urine flow is also a serious complication. If a patient is unable to pass urine or experiences a significant decrease in output, it suggests the stone is completely obstructing the ureter. This obstruction can cause severe pressure in the kidney, potentially leading to kidney damage over time. Cloudy or foul-smelling urine, sometimes accompanied by chills or shaking, also suggests an infection is present and warrants prompt medical evaluation.