A 5 mm kidney stone is one of the stones considered a “borderline size” in the clinic. That is, while it can pass on its own in some patients, in others it can become lodged in the urinary channel and require intervention. For this reason, it is not correct to say it “will definitely pass” or “will definitely not pass”; the likelihood of passing depends on various factors.
In general, a significant portion of stones up to 5 mm can pass on their own, but this process varies from patient to patient.
How Often Does a 5 mm Stone Pass on Its Own?
According to medical studies:
- Stones under 4 mm: can pass on their own in 70-90% of cases
- 5 mm stones: can pass in approximately 50-70% of cases
- Stones 6 mm and above: the likelihood of passing decreases significantly
In other words, more than half of 5 mm stones can pass without surgery under suitable conditions.
Factors Affecting the Passing of the Stone
The Location of the Stone
The location of the stone is the most important factor:
- Inside the kidney: the likelihood of passing is lower
- The upper part of the ureter: moderate
- The lower part of the ureter (close to the bladder): the likelihood of passing is higher
Stones in the lower ureter usually pass more easily.
The Structure of the Urinary Channel
The narrowing or anatomical structure of the urinary channel affects the progress of the stone.
The Patient’s Fluid Intake
Drinking enough water can facilitate the progress of the stone by increasing urine flow.
Movement and Activity
Regular walking and light movements can help the stone change position.
The Structure of the Stone
While hard stones such as calcium oxalate pass with more difficulty, smaller and smoothly structured stones can progress more easily.
Symptoms While a 5 mm Stone Is Passing
While the stone is moving, the following symptoms may be seen:
- Flank pain (in a wave-like manner)
- Pain radiating to the groin area
- Burning during urination
- Frequent urination
- Blood in the urine
- Nausea and restlessness
As the stone progresses, the pain usually “moves” downward.
How Long Does It Take for a 5 mm Stone to Pass?
The duration varies from person to person:
- It can pass within a few days
- It can take 1 to 2 weeks
- Sometimes it can extend up to 3 to 4 weeks
However, stones that do not pass within 4 to 6 weeks are usually re-evaluated.
What Is Done to Help Pass a 5 mm Stone?
Plenty of Fluid Intake
Increasing daily water intake speeds up urine flow.
Movement
Light activities such as walking are recommended.
Medication Treatment (Medical Expulsive Therapy)
By a urology specialist:
- Medications that relax the ureteral muscles
- Painkillers
can be used. This treatment can increase the chance of the stone passing.
When Is Intervention Needed?
Medical intervention may be required in the following situations:
- Severe and persistent pain
- Fever (a sign of infection)
- Inability to urinate
- The presence of a single kidney
- The stone not passing within 4 to 6 weeks
In these situations, ESWL or endoscopic methods (URS) may come into consideration.
Summary
A 5 mm kidney stone can pass on its own in most patients, but this is not certain. The location of the stone, the condition of the urinary channel, and the patient’s general characteristics directly affect this process. With proper follow-up and appropriate treatment, many patients can pass their stone without surgery, but active treatment may be required for stones that do not pass or that cause complications.
