Stones which are in the kidney
Most stones that are in the kidney do not cause pain unless they are trying to pass down from the kidney into the ureter. Treatment of kidney stones which are not causing pain or other symptoms can broadly be discussed based on the size of the stone.
Small Kidney Stones – up to 5mm

Most stones in the kidney which are small (up to 5 mm diameter) do not require treatment if they are not causing any symptoms.
These stones may pass spontaneously down the ureter without the need for surgery. Very small stones (up to 3mm) can even pass without any pain as they may not cause any blockage on their way out. Stones between 3 and 5 mm often cause pain (renal colic) while passing down the ureter.
Small stones in the kidney generally continue to grow over months or years. Some stones stay stable in size, but this is less common. Despite the fact that small stones may pass spontaneously, some patients will request treatment in order to avoid an episode of pain in the future. This is especially common in patients who have experienced severe kidney stone pain in the past.
If a decision is made not to treat a small kidney stone, it is generally monitored from time to time (often with an ultrasound) to make sure it is not growing to a size which is unlikely to pass spontaneously (greater than 5mm).
The treatment options for small kidney stones (less than 5mm) are:
- Observation only – for most patients.
- Extracorporial Shockwave Lithotripsy (ESWL).
- Ureteropyeloscopy.
Medium Kidney Stones – 5-20 mm
Medium sized stones in the kidney (5-20mm diameter) generally require treatment even if they are not causing any symptoms. This is because these calculi are unlikely to pass spontaneously and very likely to cause problems at some point in the future. These stones may cause pain, bleeding, urinary infections or more rarely kidney damage.
The treatment options for kidney stones 5-20mm are:
- Extracorporeal Shockwave Lithotripsy (ESWL).
- Ureteropyeloscopy.
- Percutaneous Nephrolithotomy – usually for larger stones.
- Observation – if the patient is too frail for an operation.

These stones are generally treated in one of two ways: Extracorporeal Shockwave Lithotripsy (ESWL) or Ureteropyeloscopy. The decision as to which of these two options is most appropriate is complex and needs to be individualised for each clinical situation. There is no one “best” treatment for kidney stones and both of these treatment modalities have their advantages and disadvantages. Here is a table which summarizes the differences.
ESWL | Ureteropyeloscopy | |
---|---|---|
Mechanism | Sound waves through skin break the stone, pieces need to pass naturally | Telescope through urethra, stone visualized with laser fragmentation then removal of stone |
Anesthetic | General Anesthetic | General Anesthetic |
Time | 30-45 min | 45-120 min |
Hospitalisation | Day case | Day case or overnight |
Complexity | Less complex | More complex |
Safety | Very safe | Very safe |
Need for stent | Stent rarely used | Usually needs a stent |
Procedures needed | Usually one | Usually two |
Success Rate | 60-80%, less if larger | 95% |
Risk of renal colic | Yes, from passing fragments | No, fragments are removed |
Stone Analysis | Not possible usually | Yes, fragments analysed |
Large Kidney Stones – greater than 20mm
Large kidney stones nearly always require treatment unless patients are too frail, or the procedure is too risky for the individual. These stones have a high chance of causing symptoms or long-term damage to the function of the kidney. Even very large stones may cause no pain at all but this does not imply that they do not require treatment. Very large stones may develop a branched appearance – these are called Staghorn Calculi. Many staghorn calculi are associated with urinary infection and include the presence of bacteria within the stone. These type of stones are potentially very serious and can even be fatal if left untreated.
The treatment options for large kidney stones are:
- Percutaneous Nephrolithotomy (PCNL).
- Ureteropyeloscopy.
- Open Renal Stone Surgery.
- Laparoscopic Surgery.
Extracorporeal Shockwave Lithotripsy (ESWL) is not generally used for stones larger than 20mm as it is ineffective and results in multiple large fragments which will not be able to pass naturally.
