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Urolithiasis - Renal & Ureteric Stones: Complete Notes

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1. Aetiology - Drivers of Calculus Formation

Mechanical / Structural

• Pelviureteric junction (PUJ) obstruction causing stasis of urine.

Environmental / Dietary

• Hot climates leading to sweating and concentrated urine.
• Specific foods (e.g., coffee) increase risk.

Systemic / Metabolic

• Hyperparathyroidism (hypercalcaemia).
• Vitamin A deficiency - causes desquamation of the urinary epithelium.

Infectious / Lifestyle

• Prolonged immobilisation.
• Urease-splitting bacterial infections.

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2. Stone Typology Matrix

Common Radiopaque Calculi

Calcium Oxalate is the most common type of renal calculi.

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Rare & Radiolucent Variants

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3. Obstruction Mechanics & Clinical Features

Dietl Crisis (Total Pelvic Obstruction)

• Urine stops draining from the renal pelvis into the ureter.
• Urine accumulates, causing massive distension of the kidney capsule (hydronephrosis).
• Patient presents with severe flank pain and swelling.
• Resolution: Stone shifts → accumulated urine flows out → swelling subsides → patient passes large quantities of dilute urine.

Physical Examination Signs

• Renal angle tenderness (CVA tenderness).
• Bimanual ballottement - specifically seen in cases of hydronephrosis.

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4. Diagnostic Investigation Pathway

Step 1: Baseline Pathology

• Urine: RME (Routine Microscopic Examination) - looks for haematuria, crystals, infection.
• Blood: Sugar, electrolytes, creatinine.

Step 2: Primary Imaging

Differential diagnosis note: Always differentiate calculi from a calcified foreign body on imaging.

Investigation of Choice (IOC): NCCT KUB

• Why non-contrast? Contrast dye is nephrotoxic. A patient with renal obstruction is already at risk of kidney damage - contrast exacerbates this.
• Secondary option: IVU (Intravenous Urogram) - strictly reserved for cases where serum creatinine is verified as normal (no underlying kidney damage).

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5. Management

Surgical Escalation Ladder (in order)

1. Conservative / Symptom Control
   ├── Analgesics          → Primary acute pain control
   ├── Antibiotics         → Infection prevention and active management
   └── Antiulcerants       → GI protection against stress

2. ESWL (Extracorporeal Shock Wave Lithotripsy)

3. PCNL (Percutaneous Nephrolithotomy)

4. RIRS (Retrograde Intrarenal Surgery)

5. Pyelolithotomy (open)

6. Nephrectomy            → End of line; reserved for severe cases

Pyelolithotomy technique: Requires precise ischaemic technique - clamp the renal artery → remove stone within ischaemic window → unclamp.

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6. ESWL - Extracorporeal Shock Wave Lithotripsy

The Procedure

• Based on blast wave dynamics.
• Ultrasonic waves (typically via a Dornier apparatus) are targeted at the stone.
• Stone is shattered into smaller pieces that travel down the ureter.
• Patient must remain perfectly still during the procedure.

Contraindications

1. Pregnancy
2. Uncontrolled bleeding disorders
3. Stones > 1.5 cm in size
4. Presence of a cardiac pacemaker
5. Children (inability to remain perfectly still)
6. Obese patients (delivery of ultrasound waves becomes physically challenging)
7. Extremely hard stones (e.g., Cystine or Calcium Oxalate Monohydrate)

Complications

• Pain - most common post-procedural complication, frequently accompanied by haematuria.
• Steinstrasse Phenomenon ("stone street") - occurs when a large calculus is successfully shattered but the multiple fragments simultaneously descend and severely clog the ureter, creating a secondary, complex obstruction requiring further intervention.

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7. Medical Expulsive Therapy (MET) & Ureteric Stone Management

First-Line: MET (Conservative)

• Alpha-blockers (e.g., Tamsulosin) - relax ureteric smooth muscle to facilitate stone passage.
• Antispasmodics
• Diuretics
• Antiulcerants (gastroprotection)

Second-Line: Intervention (if MET fails)

• Laser Lithotripsy (Laser)
• ICPL (Intracorporeal Pneumatic Lithotripsy) - Pneumatic mechanism
• Dormia Basket - utilised during ICPL for stone extraction.

• Ureterolithotomy (open or laparoscopic)

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8. Differential Diagnoses (DDx) - Always Rule Out

1. Musculoskeletal Pain
2. PLID - Prolapsed Lumbar Intervertebral Disc

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• Navy/teal design with the full topic list

• Left: Aetiology (4 colour-coded categories) + Radiopaque stone typology table + Rare/radiolucent stone table
• Right: Obstruction mechanics/Dietl Crisis + Physical exam signs + Full diagnostic investigation pathway (USG, NCCT, IVU)

• Left: Surgical escalation ladder (Conservative → ESWL → PCNL → RIRS → Pyelolithotomy → Nephrectomy) + Management overview
• Right: ESWL detail (procedure, 7 contraindications, Steinstrasse complication) + MET drug table + Endoscopic/surgical second-line options + DDx