Urolithiasis means stones within the urinary tract. Stones may occur in the kidneys, ureters—the tubes connecting the kidneys to the bladder—or the bladder itself.

Kidney stones form when substances in urine crystallise and collect together. Some remain small and cause no symptoms. Others move into the ureter and obstruct urine flow, causing severe pain. Treatment depends on the stone’s size, location and effect on the urinary system.

Concentrated urine makes it easier for crystals to develop. Factors that increase the likelihood of stones include:

• Drinking too little or losing substantial fluid through sweating.
• A previous stone or family history of stones.
• High salt intake.
• Certain medical conditions, urinary infections or inherited disorders.
• Some medicines and supplements.

There are different stone types. Calcium-containing stones are the most common; others include uric acid, infection-related and cystine stones. Knowing the stone type helps guide prevention.

A stone may be found incidentally during a scan. When symptoms occur, they can include:

• Sharp pain in the side or back, sometimes spreading towards the lower abdomen or groin.
• Pain that comes and goes in waves.
• Blood in the urine.
• Nausea or vomiting.
• Frequent or urgent urination.
• Burning or discomfort while passing urine.

These symptoms can also have other causes and should be assessed.

Fever or chills with suspected stone pain require immediate medical assessment. An infected, obstructed kidney is a urological emergency and may need urgent drainage as well as antibiotics.

Seek urgent care for:

• Severe pain that is not controlled.
• Persistent vomiting or inability to keep fluids down.
• Very little urine or inability to pass urine.

Suspected stones also need prompt assessment if you have only one functioning kidney.

Your doctor will ask about your symptoms, previous stones, medical conditions and medicines. Investigations may include:

• Urine tests: To look for blood, infection and other abnormalities.
• Blood tests: To assess kidney function and substances associated with stone formation.
• Imaging: Ultrasound or a non-contrast CT scan to identify the stone’s size, position and any obstruction.
• Stone analysis: Examination of a stone that has been passed or removed.

Ultrasound is generally the first imaging choice during pregnancy and in children. Recurrent or higher-risk stone formers may also need a 24-hour urine collection to guide prevention.

Some small ureteric stones can pass naturally. Observation is suitable only when symptoms are manageable and there is no infection, threatened kidney function or other reason for intervention.

Treatment may include pain relief, anti-sickness medicine and, for selected ureteric stones, medicine that relaxes the ureter to help passage.

Follow-up is important to confirm stone passage and recovery of kidney function. Feeling better does not replace the planned review.

Certain uric acid stones can dissolve with prescribed treatment that makes urine less acidic. This requires monitoring.

Most calcium stones cannot be dissolved with medicines. Treatment should be based on the likely stone composition rather than assuming that every stone can be dissolved.

A procedure may be advised when a stone is unlikely to pass, continues to cause symptoms, grows, obstructs drainage or is associated with infection.

1. Shock-wave lithotripsy—SWL

Shock waves delivered from outside the body break a suitable stone into smaller fragments.

2. Ureteroscopy—URS / flexible ureteroscopy—RIRS

A thin telescope passes through the urinary passage to reach the ureter or kidney. The stone can be removed or fragmented, often using a laser.

3. Percutaneous nephrolithotomy—PCNLA small opening through the back provides access to remove larger or more complex kidney stones.

The choice depends on the stone and your health. Sometimes more than one treatment session is needed.

A stent is a thin internal tube that helps urine drain from the kidney to the bladder. It may be used around stone treatment or to relieve obstruction.

Keep a clear record of when the stent must be removed or changed. Attend the arranged follow-up even if you feel well.