Kidney stones are solid masses that form in the kidneys when certain substances in the urine become highly concentrated and crystalize. These formations can vary significantly in size, shape, and composition, leading to different experiences for individuals. This article aims to clarify the specific dimension of a 0.7 cm kidney stone, providing a clearer understanding of its physical scale and potential impact within the urinary system.
Understanding 0.7 cm: A Visual Perspective
A 0.7 cm kidney stone represents a significant size within the narrow confines of the urinary tract. This dimension translates to 7 millimeters, or approximately 0.28 inches. For context, this size is comparable to a standard pea, a small grain of rice, or the rubber tip of a pencil eraser.
The internal pathways of the human body, particularly the ureters which transport urine from the kidneys to the bladder, are quite narrow. Adult ureters typically measure between 3 and 4 millimeters in diameter. Given that a 0.7 cm stone is 7 millimeters wide, it is considerably larger than the typical ureteral diameter, highlighting the challenge it presents during passage.
Implications of a 0.7 cm Kidney Stone
A 0.7 cm kidney stone carries distinct medical implications, primarily concerning its ability to pass naturally. Stones smaller than 5 millimeters often pass spontaneously. However, for stones between 5 and 10 millimeters, the spontaneous passage rate significantly decreases, with studies showing a 47% chance. Specifically, stones 6.5 millimeters or larger may have a spontaneous passage rate as low as 9% over 20 weeks. Stones between 5 and 7 millimeters may pass in about 50% of cases, but those larger than 7 millimeters rarely pass without surgical intervention.
If a 0.7 cm stone lodges in the ureter, it can create a blockage, leading to hydronephrosis. This occurs when urine backs up, causing the kidney to swell and potentially impairing kidney function. Such an obstruction also increases the risk of urinary tract infections (UTIs) due to stagnant urine. Prolonged obstruction can lead to kidney damage or severe systemic infections. The stone’s location within the urinary tract also influences its potential for natural passage and symptoms.
Common Symptoms
A 0.7 cm kidney stone often triggers noticeable symptoms, particularly as it attempts to move through the ureter. The most characteristic symptom is severe, fluctuating pain known as renal colic. This pain typically originates in the flank or back, just below the ribs, and can radiate downwards towards the abdomen, groin, or testicles in men. The intensity of this pain is often described as one of the most severe types an individual can experience.
The stone’s movement can also cause microscopic or macroscopic blood in the urine (hematuria) as it irritates the urinary tract lining. Nausea and vomiting are common responses to intense pain. The stone’s presence near the bladder can also lead to increased urinary urgency and frequency, sometimes with a burning sensation during urination. These symptoms occur because the stone blocks urine flow, causing pressure to build up in the kidney.
Management and Treatment Approaches
Managing a 0.7 cm kidney stone involves watchful waiting and active intervention, given its reduced likelihood of spontaneous passage. Initial management includes pain control and hydration to encourage movement. Watchful waiting is safe for up to four to six weeks if pain is bearable, there are no signs of infection, and the kidney is not completely blocked. Surgical treatment is generally recommended for stones 0.5 centimeters or larger, or for individuals not responding to conservative management.
Medical expulsive therapy (MET) often uses alpha-blockers like tamsulosin (Flomax®). These medications relax ureter muscles, facilitating stone passage and potentially reducing pain and hospital visits. If the stone does not pass or causes significant complications, interventional procedures are necessary.
Shock wave lithotripsy (SWL) is a non-invasive option using focused sound waves to break the stone into smaller fragments for easier passage. SWL is generally effective for stones up to 2 centimeters.
Another common approach is ureteroscopy (URS), where a thin, flexible scope is inserted through the urethra and bladder into the ureter to visualize and remove or break the stone with a laser. URS allows direct visualization and removal of stone fragments, making it suitable for stones anywhere in the ureter or kidney up to 2 centimeters. Consulting a healthcare professional is crucial for proper diagnosis and to determine the most appropriate treatment.