🔑 Key Learning
- Calcium oxalate is the most common stone type (~85%).
- CT KUB (non-contrast) is the gold standard investigation.
- Analgesia: 1st line = NSAIDs (PR diclofenac)
- <5 mm stones usually pass spontaneously
- Distal ureteric stones <10 mm may benefit from alpha blockers.
- Shockwave lithotripsy (SWL) is first-line for most small stones, but contraindicated in pregnancy and coagulopathy.
- Infected + obstructed kidney = urological emergency → nephrostomy/stent.
🧬 Pathophysiology
- Stone formation occurs due to supersaturation of urine with substances like calcium, oxalate, urate.
- Stones may form in the kidneys and migrate into the ureters, causing ureteric colic.
🧪 Types of Stones
| Type | Notes |
|---|---|
| Calcium oxalate | Most common (~85%) |
| Struvite | Mg/NH₃/PO₄ – associated with Proteus |
| Uric acid | Radiolucent – needs CT or US for detection |
⚠️ Risk Factors
- Drugs: Loop diuretics, acetazolamide, steroids, theophylline
- Hypercalcaemia (e.g. hyperparathyroidism)
- Type 1 RTA, Cystinuria
- Thiazides are protective (↑ calcium reabsorption)
👀 Clinical Features
- Sudden, severe loin-to-groin pain
- Haematuria (>90%) – usually microscopic
- Nausea/vomiting
- If infection present: fever, rigors
🧪 Investigations
- 1st Line: Non-contrast CT KUB (within 24 hrs)
- USS if: pregnancy or patient is a child/young person
- Check serum calcium and consider stone analysis
💊 Management
🔹 Analgesia
- 1st Line: NSAID (PR diclofenac often in exams)
🔹 Medical Expulsive Therapy
- Distal ureteric stones <10 mm → consider alpha blockers (e.g. tamsulosin)
🔧 Interventional Options
🧊 Renal Stones
| Stone Size | Management |
|---|---|
| <5 mm | Watchful waiting |
| <10 mm | SWL 1st line |
| 10–20 mm | SWL or ureteroscopy |
| >20 mm | Percutaneous nephrolithotomy (PCNL) |
🪠 Ureteric Stones
| Stone Size | Management |
|---|---|
| <10 mm | SWL 1st line |
| >10 mm | Ureteroscopy |
⛔ Contraindications to SWL
- Pregnancy
- Coagulopathy or anticoagulant use
🚨 Infected + Obstructed Kidney
- Urological emergency
- Urgent nephrostomy or stent insertion required
🔁 Prevention
-
If >50% calcium oxalate:
- Potassium citrate
- Thiazide diuretics
📝 Exam Clues & Clinchers
- Pain + haematuria + vomiting = think renal colic
- Radiolucent stone on AXR = uric acid → confirm with CT
- Fever + obstruction = emergency nephrostomy
- <5 mm stone = likely to pass on its own
- Struvite stone = recurrent Proteus UTI
- Sudden pain + known single kidney = urgent CT KUB
🔗 Useful Links and References
NICE. Renal and ureteric stones: assessment and management [2019]. Available at URL: https://www.nice.org.uk/guidance/ng118/resources/renal-and-ureteric-stones-assessment-and-management-pdf-66141605137093