Kidney stones are common and can be extremely painful. With modern imaging and endoscopic techniques, almost all stones can be cleared safely - usually without open surgery.
Kidney stones are solid deposits that form when minerals and salts in the urine become concentrated enough to crystallise. They can sit quietly inside the kidney for months or years, or they can move into the ureter and cause sudden severe pain - renal colic.
Most patients present with pain in the loin that radiates around the flank into the groin, often with nausea and vomiting.1 The pain is usually severe, comes in waves, and is unrelated to movement - unlike musculoskeletal pain, sitting still does not make it better. See the dedicated symptoms page for a detailed discussion.
Kidney stones are common: approximately one in ten people is affected during their lifetime, and after a first stone there is a meaningful chance of forming another one without preventive measures.1, 22 The exact risk of recurrence depends on the type of stone and the underlying cause, which is why identifying both is an important part of long-term management (see Preventing recurrence below).
Pain from a kidney stone together with a fever is a medical emergency. It suggests that the stone is obstructing the kidney and that urine upstream of the blockage has become infected - a condition called obstructive pyelonephritis. International guidelines recommend urgent decompression of the kidney (usually by placing a ureteric stent or a percutaneous nephrostomy tube), together with immediate intravenous antibiotics.22
Seek emergency care without delay if any of the following occurs:
These features can indicate sepsis from an infected obstructed kidney and need hospital assessment immediately.22 See the emergency signs page for a fuller explanation.
Assessment typically includes a clinical examination, urine test, imaging (usually CT KUB), and blood tests. CT has pooled sensitivity around 95 per cent and specificity around 96 per cent for urinary stones.2, 22, 37 See the detailed diagnosis & imaging page for how each test is used.
There are four main types of kidney stone.4, 5, 35
See the stone types hub for a dedicated page on each.
Modern guidelines recommend that treatment be individualised to four main factors: the patient's symptoms, the size of the stone, its location, and the presence of any obstruction or infection.22, 23
A stone that is obstructing the kidney, particularly with any sign of infection, is a surgical emergency - the kidney is drained first (stent or nephrostomy) and the stone itself is treated at a later date once the infection has cleared.22
Selected small, non-obstructing kidney stones that are not causing symptoms can be kept under regular imaging review rather than treated immediately, in line with current international guidelines. See observation & active surveillance for details.22, 23
Sydney Kidney Stone Clinic offers the full range of contemporary kidney stone treatments. The recommended treatment is matched to the individual patient after discussion of the options and the evidence for each.
For distal ureteric stones up to about 10 mm, alpha-blocker medication (most commonly tamsulosin) taken for up to about 30 days increases the chance of spontaneous stone passage. This is a strong, Grade A recommendation in the AUA 2026 guideline.22, 23
ESWL uses focused shockwaves delivered from outside the body to break a stone into small fragments that are then passed in the urine. Best suited for stones under approximately 1 cm in the kidney and selected ureteric stones.22, 23
A thin telescope is passed along the urethra, through the bladder, and into the urinary tract to reach the stone. The stone is fragmented with a Holmium:YAG laser - the well-established international standard for intracorporeal stone lithotripsy.7, 27 Dr Kooner's usual approach is to aim for complete clearance at the time of the procedure using a dedicated extraction basket, rather than leaving fragments to pass on their own.
For large kidney stones (greater than 2 cm) and stag-horn stones, PCNL is the recommended first-line treatment in both the EAU 2025 and AUA 2026 guidelines.22, 23 PCNL is keyhole surgery of the kidney: a small puncture is made through the skin into the kidney under imaging guidance, and the stone is broken up and removed piece by piece.
An obstructed kidney that has become infected must be drained urgently, before the stone itself is addressed. This is done either by a ureteric stent placed from below under cystoscopy, or by a percutaneous nephrostomy tube placed from above through the flank.22
Recovery depends on the procedure performed. The following is a general guide; the individual post-operative plan is tailored to each patient. See what to expect for a fuller description.
After a first kidney stone, the single most important preventive measure is increasing fluid intake so that the urine stays dilute. Guidelines recommend a daily urine output of around 2.5 L.22, 24 A 2026 systematic review concluded that, of the many strategies trialled, increased fluid intake and a high-calcium, low-protein, low-sodium diet remain the best-evidenced general measures for preventing stone recurrence.33
See the dedicated prevention hub for pages on hydration, diet and medications. Patients who form recurrent stones are offered a formal metabolic evaluation and, where appropriate, referral to a renal physician colleague for detailed assessment and tailored preventive therapy.
No. Small stones of about 4 mm or less often pass on their own with adequate fluid intake and analgesia. Selected small, non-obstructing kidney stones that are not causing symptoms can also be kept under active surveillance.22, 23
Most stones that are going to pass do so within four to six weeks. If the stone has not passed in that time, or if there is unremitting pain, fever, or a decline in kidney function, active treatment is offered rather than continuing to wait.22
It depends on the size and location of the stone, its hardness on CT, the patient's general health, and patient preference. In broad terms: MET for selected small distal ureteric stones; ESWL or ureteroscopy for stones up to about 1 to 2 cm; flexible ureteroscopy with laser or PCNL for larger kidney stones; PCNL as first-line for stones larger than 2 cm and for stag-horn stones.22, 23
Yes, in most cases. Flexible ureteroscopy with Holmium laser lithotripsy is commonly used as the stone treatment for patients who cannot safely come off anticoagulant or antiplatelet therapy, because it avoids both the renal puncture of PCNL and the tissue shockwaves of ESWL. Whether any medication is paused around the operation is decided case-by-case with the treating cardiologist or haematologist.22, 30, 36
A stone that is obstructing the kidney for a prolonged period, or one that is associated with infection, can damage kidney function. A single episode of renal colic that resolves quickly, without infection, rarely leaves any lasting damage.22
Without preventive measures, roughly half of patients will form another stone within 5 to 10 years.22 With attention to hydration, diet and - where appropriate - targeted medical therapy based on a metabolic workup, the risk can be meaningfully reduced.22, 24, 33
Arrange a consultation or request a second opinion on an acute stone, a recurrent stone problem, or a recommended procedure.