🔑 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

TypeNotes
Calcium oxalateMost common (~85%)
StruviteMg/NH₃/PO₄ – associated with Proteus
Uric acidRadiolucent – 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
non-contrast CTKUB, coronal view - bilateral renal calculi. Kristie Guite, Louis Hinshaw and Fred Lee, CC BY 3.0, via wikimedia commons

     

💊 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 SizeManagement
<5 mmWatchful waiting
<10 mmSWL 1st line
10–20 mmSWL or ureteroscopy
>20 mmPercutaneous nephrolithotomy (PCNL)

  

🪠 Ureteric Stones

Stone SizeManagement
<10 mmSWL 1st line
>10 mmUreteroscopy

    

⛔ 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