Kidney and Ureteral Stones Guide: Causes, Symptoms, and Laser Treatment
Few pains arrive as suddenly as renal colic. A person can feel well in the morning, then develop severe flank pain, nausea, sweating, and an urgent need for medical help within hours. The usual cause is a stone moving from the kidney into the ureter, the narrow tube that drains urine to the bladder.
Kidney stones are common, but they are not all the same. Their chemistry matters. A small calcium oxalate stone may pass with pain relief and fluids. A large staghorn struvite stone linked to infection may need surgery. A dense ureteral stone stuck low in the pelvis may need laser lithotripsy.
This guide explains how stones form, what renal colic feels like, how doctors diagnose stones, and how modern ureteral stone treatment works, including Extracorporeal Shock Wave Lithotripsy (ESWL), percutaneous nephrolithotomy, and flexible ureteroscopy with laser treatment.
This article is for general medical information only. It cannot replace assessment by a clinician, especially if pain is severe, fever is present, or urine output falls.
How kidney and ureteral stones form
Urolithiasis means stone formation within the urinary tract. Stones usually begin in the kidney, where urine becomes concentrated enough for minerals to crystallise. The central chemical problem is supersaturation.
Supersaturation happens when urine contains more dissolved minerals than it can safely hold. Once that threshold is crossed, crystals can form. If urine contains enough natural inhibitors, such as citrate, crystals may stay tiny and pass unnoticed. If inhibitors are low, or urine remains concentrated for long periods, crystals can grow into stones.
Several factors push urine towards supersaturation:
Low fluid intake or high fluid loss through sweating
High urinary calcium, oxalate, uric acid, or cystine
Low urinary citrate
Recurrent urinary tract infection
Certain metabolic or genetic conditions
Diets very high in salt, animal protein, or oxalate-rich foods
Some medicines and supplements in susceptible people
A stone causes the most trouble when it leaves the kidney and enters the ureter. The ureter is narrow, muscular, and sensitive to blockage. When urine cannot drain freely, pressure rises in the kidney, the ureter spasms, and renal colic begins.
The main types of stones and why chemistry matters
Stone analysis is more than a label. It can guide prevention, diet, medication, and follow-up. Many stones contain a mixture of materials, but most fall into a few main groups.
Stone type | Common features | Prevention focus |
Calcium oxalate and calcium phosphate | The most common kidney stones. They may relate to dehydration, high urinary calcium, high oxalate, low citrate, or high salt intake. | Increase fluids, reduce salt, keep normal dietary calcium, review oxalate intake, treat metabolic risks. |
Uric acid | More likely in acidic urine. Linked with gout, metabolic syndrome, high animal protein intake, and low urine pH. | Alkalinise urine, improve hydration, reduce purine load where needed, consider medication if recurrent. |
Struvite | Infection-related stones caused by urease-producing bacteria. Can grow quickly and form large branching stones. | Treat infection, remove stone burden when needed, prevent recurrent infection. |
Cystine | Caused by cystinuria, an inherited condition that increases cystine in urine. Often recurrent and starts younger. | High fluid intake, urine alkalinisation, specialist medication in selected cases. |
Calcium stones do not usually mean someone should stop eating calcium. Very low dietary calcium can increase oxalate absorption from the gut and may raise stone risk. In many cases, the safer approach is normal calcium intake with meals, lower salt intake, and better hydration.
Uric acid stones differ because they can sometimes dissolve when urine pH is raised under medical supervision. That makes accurate diagnosis useful. CT appearance, urine pH, blood tests, and stone analysis all help build the picture.
Symptoms and diagnosis of renal colic
Renal colic often has a distinctive pattern. Pain usually starts in the loin or flank and may travel towards the groin as the stone moves down the ureter. The pain can come in waves, but it is often intense enough that sitting still feels impossible.
Common symptoms include:
Severe flank or abdominal pain
Pain spreading to the groin, testicle, or labia
Nausea or vomiting
Blood in the urine, sometimes visible and sometimes only on testing
Frequent or urgent urination when the stone is near the bladder
Sweating, restlessness, and distress
Fever changes the situation. A blocked kidney plus infection can become dangerous. It needs urgent medical care, antibiotics, and often drainage with a ureteric stent or nephrostomy tube.
Doctors usually confirm kidney stones with a mix of clinical assessment, urine testing, blood tests, and imaging. In the UK, non-contrast CT KUB is often the most accurate test for suspected ureteric stones. KUB refers to kidneys, ureters, and bladder. It can show stone size, position, density, and whether the kidney is obstructed.
Ultrasound can help, especially when avoiding radiation matters, such as during pregnancy. It may show swelling of the kidney or larger renal stones, but small ureteric stones can be harder to see. A plain X-ray may help follow some calcium-containing stones, but it misses radiolucent stones such as many uric acid stones.
Blood tests often check kidney function, infection markers, calcium, and uric acid. Urine tests look for blood, infection, pH, and crystals. If a stone passes, saving it for laboratory analysis can be highly useful.
Pain relief and medical treatment during an attack
Renal colic treatment starts with pain control, nausea treatment, and assessment for complications. Clinicians often use non-steroidal anti-inflammatory drugs when safe, because they reduce pain and may lower pressure inside the affected kidney. Examples include diclofenac or ibuprofen, but they are not suitable for everyone, especially people with certain kidney, stomach, bleeding, or cardiovascular risks.
Other measures may include:
Paracetamol for extra pain relief
Anti-sickness medication
Opioid pain relief for severe pain when needed
Fluids if dehydration is present
Antibiotics if infection is suspected or confirmed
Drinking huge amounts of water during acute colic does not force the stone out and may worsen nausea. The aim is normal hydration, not overloading the blocked system.
Some people benefit from medical expulsive therapy. This often means an alpha-blocker such as tamsulosin, used for selected ureteric stones, especially lower ureteric stones of a size likely to pass. The decision depends on stone size, location, symptoms, kidney function, infection risk, and local guidance.
A stone is more likely to need intervention if it is large, causes ongoing severe pain, blocks the kidney, affects kidney function, or does not pass after a period of observation. A single functioning kidney, pregnancy, recurrent infection, or uncontrolled vomiting can also change the urgency.
Modern stone removal options
The best procedure depends on stone size, location, density, anatomy, infection status, bleeding risk, and patient preference. No single method suits every stone.
Extracorporeal Shock Wave Lithotripsy uses sound waves from outside the body
Extracorporeal Shock Wave Lithotripsy (ESWL) breaks stones using focused shock waves generated outside the body. The fragments then pass naturally in the urine.
ESWL can work well for selected kidney stones and some upper ureteric stones, particularly when stones are smaller, less dense, and easy to target. It avoids instruments passing through the urinary tract, which is a major advantage.
Its limits matter. Hard stones may not fragment well. Lower pole kidney stones may leave fragments behind. Larger stones may need repeat sessions or another treatment. Some people develop bruising, blood in the urine, pain from passing fragments, or temporary blockage from stone debris.
Ureteroscopy treats stones through the natural urinary passage
Ureteroscopy passes a thin telescope through the urethra and bladder into the ureter. For ureteric stones, this allows direct treatment without a skin incision. The surgeon can retrieve small stones with a basket or break larger ones with a laser.
Laser lithotripsy commonly uses holmium or thulium laser systems. The laser fibre touches or approaches the stone and breaks it into dust or fragments. The surgeon may remove fragments or leave fine dust to pass naturally.
A temporary ureteric stent may be placed after the procedure. A stent helps urine drain while swelling settles, but it can cause urinary frequency, discomfort, blood in the urine, or bladder irritation until removed.
Flexible ureteroscopy and RIRS reach stones inside the kidney
Flexible ureteroscopy allows the instrument tip to bend inside the kidney’s collecting system. When surgeons use this approach to treat kidney stones, it is often called retrograde intrarenal surgery, or RIRS.
RIRS with laser lithotripsy suits many stones that are too difficult to pass but not large enough to require a percutaneous operation. It is especially useful when ESWL is unlikely to work or when a more direct approach is preferred.
Percutaneous nephrolithotomy treats large or complex kidney stones
Percutaneous nephrolithotomy, or PCNL, treats larger kidney stones through a small channel made from the skin into the kidney. The surgeon passes instruments directly into the kidney, breaks the stone, and removes fragments.
PCNL is often used for large stones, complex stones, and staghorn stones. It has a higher stone-clearing power for bulky disease, but it is more invasive than ESWL or ureteroscopy. Risks include bleeding, infection, injury to nearby structures, and the need for a hospital stay.
Preventing kidney stones from coming back
Prevention begins with understanding the stone. A first-time small stone may need simple advice. Recurrent stones, bilateral stones, cystine stones, infection stones, or stones in younger patients often need a fuller metabolic work-up.
The most reliable prevention step for many people is to produce more dilute urine. Many clinicians advise aiming for pale urine through the day, unless another medical condition limits fluid intake. Water is usually the best default.
Diet can make a real difference:
Keep salt intake low, because high sodium can increase urinary calcium.
Maintain normal dietary calcium, preferably from food.
Avoid excessive animal protein, especially with uric acid stones.
Pair oxalate-rich foods with calcium-containing foods if advised.
Eat fruit and vegetables to support citrate levels.
Avoid high-dose vitamin C supplements unless prescribed, as they may raise oxalate in some people.
Some people need medication. Thiazide-type diuretics may reduce urinary calcium in selected patients. Potassium citrate can help low citrate levels and can alkalinise urine for uric acid or cystine risk. Allopurinol may help some people with high uric acid production or recurrent uric acid stones. Infection stones need careful infection control and stone clearance where possible.
Follow-up imaging matters because silent stones can grow without pain. The right interval depends on risk level, previous procedures, and stone type.
If fertility, men’s health, urinary pain, or recurrent stone symptoms are affecting day-to-day life, you can book a specialist appointment online for a focused assessment.
FAQ
Can a kidney stone pass on its own?
Yes, many small stones pass without surgery, especially if they are already low in the ureter. Larger stones, persistent blockage, infection, or uncontrolled pain make spontaneous passage less likely or less safe.
Is laser lithotripsy painful?
The procedure is usually done under anaesthetic, so pain during treatment is controlled. Some discomfort, stent symptoms, urinary frequency, and blood in the urine can occur afterwards.
Is ESWL better than ureteroscopy?
Neither is always better. ESWL is less invasive and works well for selected stones. Ureteroscopy gives direct access to the stone and may be more suitable for hard, impacted, or less favourable stones.
What foods cause calcium stones?
Calcium stones often relate more to low fluid intake, high salt intake, high urinary calcium, high oxalate, or low citrate than to calcium-rich foods alone. Most people should not cut out dietary calcium unless a clinician advises it.
When is renal colic an emergency?
Seek urgent care for fever, shivering, severe uncontrolled pain, vomiting that prevents fluids, reduced urine output, pregnancy, a single kidney, or known kidney disease.
Key takeaway
Kidney stones are a chemistry problem, a plumbing problem, and sometimes an infection problem. Good care starts by identifying the stone’s size, site, and type. Pain control and safe observation may be enough for small stones, while ESWL, ureteroscopy with laser lithotripsy, RIRS, and PCNL can treat stones that are too large, painful, or risky to leave alone.
The best long-term plan does not end after the stone passes. Stone analysis, urine testing, hydration, diet changes, and targeted medication can reduce the chance of another attack.
Comments