Renal colic (kidney stones)
NSAID first for the pain, urine dip, scan to confirm, and remember the two dangers: an infected blocked kidney and a leaking aortic aneurysm pretending to be colic.
A 34-year-old man who works outdoors is rolling around with severe pain from his right loin to his groin. He has vomited. Urine dipstick shows blood 3+. Temperature 37.0 °C, BP 142/88. He had a similar episode two years ago.
What do you give for the pain, and what would change your plan?
- Pain reliefAn NSAID first, unless contraindicated.
- TemperatureFever with a blocked kidney is an emergency: drainage plus antibiotics.
- Urine dipstick and cultureBlood supports a stone. Nitrites or leucocytes suggest infection.
- BloodsCBC, creatinine, electrolytes, calcium, uric acid, CRP.
- Pregnancy testIn women.
- Over 60, or first ever "colic"Think leaking AAA. Check BP and feel the abdomen.
- ImagingNon-contrast CT KUB within 24 hours. Ultrasound in pregnancy and young people.
- PlanPass it, help it pass, or remove it.
- Fever with a blocked kidney
- AKI, single kidney or stones on both sides
- Over 60 with low BP or a pulsatile mass
- Pregnant
- Pain not controlled
- Infected obstructed kidney
- Leaking AAA
- Obstruction of a single kidney
- Ectopic, torsion or appendicitis mimicking colic
| Pain | NSAID first (IM, rectal or oral). Paracetamol IV if NSAID unsuitable. Opioid if both fail |
| Stones under 5 mm | Usually pass on their own |
| Distal ureteric stone under 10 mm | Tamsulosin can help it pass |
| Fever with obstruction | Antibiotics plus urgent drainage (stent or nephrostomy) |
| Single kidney, both sides blocked, or AKI | Urgent urology |
Check every dose against a current drug reference and your hospital protocol.
On this page
What it is
A stone moving down the ureter causes waves of severe pain from the loin to the groin (and testis or labia), often with vomiting. Patients cannot keep still. Kidney stones are common in Pakistan, where hot summers and dehydration (outdoor work, low water intake) concentrate the urine.
Two dangers
- Fever, rigors, loin tenderness
- Raised white count and CRP
- Urine nitrites
- Antibiotics plus urgent drainage: pus under pressure kills
- Over 60, first episode, smoker
- Low BP or fainting
- Pulsatile mass
- Vascular surgeon now
Pain relief
- NSAIDs work better than opioids for renal colic and reduce the need for more painkillers.
- No routine IV fluid loading: it does not help the stone pass.
Investigations
| Test | Why |
|---|---|
| Urine dipstick | Blood in most stones (not all). Nitrites and leucocytes suggest infection |
| Urine culture | Before antibiotics if infection is possible |
| CBC, CRP | Infection |
| Creatinine, electrolytes | Kidney function before NSAIDs and contrast |
| Calcium, uric acid | Causes of stones |
| Pregnancy test | Women |
| Non-contrast CT KUB | Best test. Stone size and position, obstruction, other diagnoses |
| Ultrasound | Pregnancy, children, young adults. Shows hydronephrosis |
Will it pass?
Likely to pass. Home with painkillers, plenty of fluids, strain the urine, follow-up
- Tamsulosin can help. Urology follow-up within a few weeks
- Return if pain uncontrolled or fever
Urology: ureteroscopy, shock-wave lithotripsy, or PCNL for large kidney stones
When drainage is urgent
- Fever with obstruction (infected obstructed kidney).
- AKI, a single kidney, or both kidneys blocked.
- Pain that cannot be controlled.
Preventing more stones
- Drink more water: enough to pass 2–2.5 litres of pale urine a day, more in summer and for outdoor workers.
- Less salt and less meat protein. Normal calcium intake (do not cut out dairy).
- Recurrent stones: stone analysis, calcium, uric acid and urine tests to find a cause (for example high calcium from parathyroid disease).
Common mistakes
- Calling an older man's first "renal colic" without checking for an AAA.
- Missing a fever: an infected blocked kidney needs drainage, not just antibiotics.
- Giving only opioids when an NSAID would work better.
- Giving NSAIDs to a patient with AKI or dengue.
- Forgetting a pregnancy test in women.
Frequently asked questions
What is the best painkiller for renal colic?
An NSAID such as diclofenac (IM, rectal or oral) is first line. IV paracetamol if NSAIDs are unsuitable, and an opioid only if both fail.
Which kidney stones pass on their own?
Most stones under 5 mm pass on their own. Distal ureteric stones of 5–10 mm may pass with tamsulosin. Larger stones usually need a procedure.
When does renal colic need urgent drainage?
When there is fever with obstruction (an infected obstructed kidney), acute kidney injury, a single kidney, both kidneys blocked, or uncontrolled pain.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A patient has a 4 mm distal ureteric stone. Pain is controlled, there is no fever and creatinine is normal. What is the best plan?
Answer: Home with an NSAID. Stones under 5 mm usually pass. Return if fever, uncontrolled pain or reduced urine.
- Open surgery: Not indicated.
- Admit for IV antibiotics: No infection.
- Urgent ureteroscopy: Most small stones pass.
- Nephrostomy: No obstruction-infection emergency.
2. A 68-year-old smoker has his first episode of "renal colic" and BP 92/60. What must be excluded?
Answer: Leaking aortic aneurysm. A first "renal colic" in an older patient, especially with low BP, is a leaking AAA until proven otherwise.
- Pyelonephritis: Less urgent.
- Testicular torsion: Not this picture.
- Musculoskeletal pain: Dangerous assumption.
- Appendicitis: Not this age and presentation.
3. A patient with loin pain has fever 39 °C and CT shows a 6 mm stone with hydronephrosis. What is needed?
Answer: IV antibiotics and urgent urological drainage. An infected obstructed kidney needs drainage within hours by stent or nephrostomy.
- Lithotripsy today: Drain first.
- Oral antibiotics and review in a week: Dangerous.
- Observation: No.
- Tamsulosin and home: Infected and obstructed.
4. A 35-year-old man has severe loin-to-groin pain and haematuria. He is afebrile. Which imaging confirms a ureteric stone?
Answer: Non-contrast CT KUB. Non-contrast CT KUB is the most sensitive test for urinary stones (uric acid stones too). Ultrasound is first-line in pregnancy and children. Stones < 5 mm usually pass; tamsulosin helps distal stones 5–10 mm. Urgent decompression (nephrostomy or stent) for obstructed infected kidney, solitary kidney, or AKI. Most stones are calcium oxalate.
- Plain X-ray KUB only: Plain X-ray misses radiolucent stones.
- IV urogram first: IVU has largely been replaced by CT.
- MRI abdomen: MRI is poor for calcification.
5. A 40-year-old man has sudden severe left loin-to-groin pain and is rolling around in agony. Urine dipstick shows blood. He is afebrile and renal function is normal. What is the first-line analgesia?
Answer: IM/IV diclofenac (NSAID). NSAIDs (by any route, e.g. IM or rectal diclofenac) are first-line for renal colic: they reduce pain and ureteric spasm. Use IV paracetamol if NSAIDs are contraindicated and opioids as third line. Antispasmodics are not recommended. Non-contrast CT KUB confirms the stone. Fever with obstruction is an emergency needing drainage.
- IV paracetamol alone: Second-line when NSAIDs are contraindicated.
- Oral codeine: Weak and slow for renal colic.
- IV morphine as first choice: Opioids are used if NSAIDs fail or are contraindicated.
6. A girl has a duplex kidney with two ureters on one side. What is the embryological cause?
Answer: Split or double ureteric bud. The ureteric bud (from the mesonephric duct) forms the ureter, pelvis, calyces and collecting ducts, inducing the metanephric blastema to form nephrons. Early bifurcation gives a bifid ureter; two separate buds give a complete duplex system (the upper pole ureter inserts lower and more medially and may be ectopic or obstructed — Weigert–Meyer rule). In girls an ectopic ureter below the sphincter causes continuous dribbling.
- Failure of kidney ascent: Pelvic kidney.
- Fusion of metanephric masses: Horseshoe kidney.
- Persistent mesonephros: Not this.
- Failed urorectal septum: Anorectal anomalies.
7. A young man has sudden loin-to-groin pain with microscopic haematuria after a game of cricket. What is the investigation of choice to confirm a ureteric stone?
Answer: Non-contrast CT KUB. Non-contrast CT KUB is the investigation of choice for suspected renal colic. It detects almost all stones regardless of composition (even radiolucent uric acid stones), shows their size and position, any obstruction, and other causes of pain. It needs no contrast and is fast. A plain X-ray misses radiolucent and small stones and is mainly used for follow-up of known radio-opaque stones. The intravenous urogram has been largely replaced. Ultrasound is preferred in pregnancy and children to avoid radiation.
- Plain X-ray KUB: A plain film misses radiolucent and small stones.
- Intravenous urogram: The intravenous urogram needs contrast and has been largely replaced by CT.
- Bladder ultrasound: Bladder ultrasound alone cannot show a ureteric stone.
- MRI of the abdomen: MRI is not used first for stones.
References and dose sources
- NICE NG118: Renal and ureteric stones, assessment and management
- EAU guidelines on urolithiasis
- NICE NG156
- BAUS — stone guidance
- Diclofenac dosing: Drugs.com: Diclofenac dosage (see also our diclofenac dose page)
- Paracetamol dosing: Drugs.com: Acetaminophen (paracetamol) dosage (see also our paracetamol dose page)
- Morphine dosing: Drugs.com: Morphine dosage (see also our morphine dose page)
- Tamsulosin dosing: Drugs.com: Tamsulosin dosage (see also our tamsulosin dose page)
- Ceftriaxone dosing: Drugs.com: Ceftriaxone dosage (see also our ceftriaxone dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.