Renal stones surgery mbbs topic

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Renal Stones (Urolithiasis) - Surgery MBBS

Sources: Bailey & Love's Short Practice of Surgery 28th Ed., Schwartz's Principles of Surgery 11th Ed., Campbell-Walsh-Wein Urology

1. Introduction & Epidemiology

Urolithiasis is as old as mankind - the first documented cystolithotomy was performed by Sushruta (~600 BCE). It remains a major surgical problem with increasing incidence of renal calculi in the modern world (though bladder stones have declined due to improved nutrition).

Lifetime prevalence: 1-20% (varies by geography)
Recurrence: ~50% within the first decade of diagnosis
Sex: Men are twice as likely as women to form stones
Peak age: Men - 4th to 6th decade; Women - bimodal (3rd decade + postmenopausal)
Ethnicity: White > other groups (though diet/environment may matter more)
Family history: 2.5x increased risk

2. Pathogenesis

Stone formation is a cascade of events:

Concentration of culprit salts (Ca²⁺, oxalate) overwhelms inhibitors (citrate, Tamm-Horsfall mucoprotein, magnesium, K⁺)
Crystals precipitate and nucleate
Crystal nuclei either wash away or anchor at Randall's plaques on renal papillae
Urine pH matters: acidic urine → uric acid stones; alkaline urine → calcium phosphate stones
Stasis promotes formation of smooth, round "milk of calcium stones"

3. Types of Renal Stones

Stone Type	Frequency	Key Features
Calcium oxalate	60-85%	Most common; associated with hypercalciuria, hyperoxaluria, hypocitraturia
Calcium phosphate	Rare (pure)	Apatite (infection), Brushite (distal RTA)
Struvite (infection)	~15%	Urease-producing bacteria (Proteus, Klebsiella, Serratia); forms staghorn calculi
Uric acid	~5-10%	Acidic urine; associated with gout, myeloproliferative disorders
Cystine	~1%	Autosomal recessive cystinuria; very hard, resistant to SWL

Staghorn Calculi

Infection stones growing in a branching pattern that fills the entire pelvicalyceal system. They can grow very large before detection, causing significant morbidity including loss of renal function from chronic infection and obstructive uropathy. Complete clearance is mandatory - residual fragments cause rapid recurrence. Long-term chemoprophylaxis is required after removal.

4. Clinical Presentation

Ureteric/renal colic: Most common acute presentation - sudden onset excruciating flank pain radiating to groin, scrotum, or labia; caused by hyperperistalsis against the obstructing stone
Haematuria: Gross or microscopic (especially during colic episodes)
Calculuria: Passage of sand or gravel in urine
Lower ureteric stones: Urinary urgency and frequency (near vesico-ureteric junction)
Asymptomatic: Increasingly common with widespread imaging
Sepsis: High-grade fever with chills = urological emergency requiring immediate decompression

5. Investigations

Investigation	Role
NCCT (Non-contrast CT)	Investigation of choice - detects both radio-opaque AND radiolucent stones (exception: indinavir stones)
KUB X-ray + USG	Good first-line tests
Urinalysis	Microscopic haematuria, pyuria, crystals, pH
Urine culture	Before definitive surgery; if sepsis suspected
Serum Ca²⁺, phosphate, uric acid	Rule out hypercalcaemia, hypophosphataemia, hyperuricaemia
Serum electrolytes, creatinine	Renal function baseline

6. Management Algorithm

Step 1 - Conservative / Medical

Watchful waiting: Small (<5 mm), non-obstructive, asymptomatic stones may be followed up.

Up to 90% of 4-mm stones pass spontaneously
Up to 50% of 6-10 mm stones pass spontaneously
Observation period: 4-6 weeks for ureteral stones ≤10 mm

Medical Expulsive Therapy (MET):

Tamsulosin (α1-blocker) - relaxes distal ureteric smooth muscle; used for distal ureteric stones >5 mm and to assist passage after SWL
α-blockers improve stone passage rate from 54% → 77% for distal ureteral stones ≤10 mm (per meta-analyses)
Calcium channel blockers - reduce dysmotile ureteric contractions

Analgesia: NSAIDs first-line; opioids if required

Emergency Decompression (if sepsis, obstruction, or refractory pain):

Ureteric stenting (JJ stent) OR
Percutaneous nephrostomy (PCN)

7. Surgical Management

Key principle: Choose the least invasive method appropriate for that particular stone.

Open surgery is now of historic interest only - <1% of stone surgery requires open access with modern endourology.

A. Extracorporeal Shockwave Lithotripsy (ESWL / SWL)

Introduced in 1980 by Christian Chaussy - first non-invasive stone treatment
Completely non-invasive outpatient procedure

Mechanism: Stone localised by fluoroscopy/USG → acoustic pulse waves focused on stone → fragmentation by mechanical stress from shockwave + cavitation bubble collapse

Indications:

Proximal ureteral stones (especially <10 mm)
Non-lower-pole renal stones <2 cm

Contraindications:

Pregnancy
Bleeding diathesis/anticoagulation
Untreated UTI
Aortic/renal artery aneurysm
Uncorrected obstruction distal to stone
Morbid obesity (stone unreachable)
Pacemaker (relative)

Complications:

Steinstrasse ("street of stones") - row of stone fragments lining the distal ureter, may cause obstruction; usually pass spontaneously, but may need intervention
Subcapsular/perinephric hematoma
"Clinically insignificant residual fragments" (≤4 mm) - expected to pass but 20-40% do not and can become a nidus for regrowth

Steinstrasse - KUB showing stone fragments lined in right distal ureter after ESWL

Figure: Steinstrasse formation at the right distal ureter after ESWL (Bailey & Love, 28th Ed.)

B. Ureteroscopy (URS) / Ureterorenoscopy

Ureterorenoscopes (semirigid or flexible) are long thin scopes with working channels for energy sources, graspers, and baskets.

Indications:

Middle and distal ureteral stones (procedure of choice)
Proximal ureteral stones >10 mm (higher success than SWL)
Renal stones (flexible URS)

Energy sources used for lithotripsy:

Pneumatic lithotripter (semirigid URS)
Holmium:YAG laser - most widely used, can be delivered via flexible instruments

Steps: Ureteroscope advanced to stone → fragmented under direct vision → fragments removed with nitinol basket OR left to pass

Post-procedure: JJ ureteric stent usually placed (major source of patient morbidity, though temporary)

Complications:

Ureteric perforation
Ureteric avulsion (avoided by careful basket use under vision)
Ureteric stricture (long-term)
Retropulsion of stone

Advantage over SWL: Surgeon can visualise fragmentation and control fragment size; active stone removal possible

C. Retrograde Intrarenal Surgery (RIRS)

A slimmer, flexible URS with active tip deflection + laser technology provides retrograde access to kidney via the ureteric orifice. Avoids morbidity of PCNL.

Indications:

Renal stones <2 cm
Lower pole calculi
Obesity
Musculoskeletal deformities (kyphoscoliosis)
Renal anomalies (horseshoe kidney, pelvic kidney)
Bleeding diathesis

D. Percutaneous Nephrolithotomy (PCNL)

PCNL involves creating a tract between the skin and the pelvicalyceal system for direct access to large renal stones.

Position: Prone (standard); supine (modified - Valdivia position)

Access: Fluoroscopy or USG guidance; posterolateral calyx is the preferred entry point

Steps:

Needle access into selected calyx under imaging guidance
Guidewire insertion
Serial dilatation to create a working tract (typically 24-30Fr)
Nephroscope introduced
Stone fragmented using pneumatic + ultrasound lithotripter or laser
Fragments removed with graspers
Nephrostomy tube left in situ (or "tubeless PCNL" in selected cases)

Energy sources: Pneumatic, ultrasound (most common combination for PCNL), laser

Indications for PCNL:

Renal stones >2 cm
Staghorn calculi
Lower pole renal stones with anatomy unfavourable for SWL
Failed SWL or RIRS
ESWL-refractory stones <2 cm

Contraindications to PCNL:

Pregnancy
Untreated UTI
Bleeding diathesis
Current anticoagulation

Complications:

Bleeding (may require selective angioembolisation for pseudoaneurysm/AVF)
Infection/urosepsis
Pleural violation (supracostal puncture → pneumothorax/hydrothorax)
Injury to adjacent organs (colon, spleen, liver)
Residual stones

Mini-PCNL (miniaturised PCNL): Uses smaller instruments (mini-perc); equivalent stone-free rates with less bleeding; useful for smaller complex stones

Steinstrasse (post-ESWL complication)

KUB showing Steinstrasse in right distal ureter

Figure: KUB - Steinstrasse in the right distal ureter (arrows) (Schwartz's Surgery 11th Ed.)

8. Choice of Procedure - Decision Matrix

Stone Size & Location	Preferred Procedure
≤5 mm, asymptomatic	Watchful waiting + MET
5-10 mm, distal ureter	MET (tamsulosin), then URS if fails
≤10 mm, proximal ureter	SWL first; URS if fails
>10 mm, proximal ureter	URS (higher success than SWL)
<2 cm, non-lower-pole renal	SWL or RIRS
<2 cm, lower pole renal	RIRS or PCNL (SWL has poor clearance due to gravity)
>2 cm, renal	PCNL
Staghorn calculi	PCNL
Cystine stones	PCNL or URS (resistant to SWL)

9. Indications for Urgent/Emergency Surgical Intervention

Failure of medical management
Sepsis with obstruction (emergency decompression - JJ stent or PCN)
Impaired renal function (obstructive uropathy)
Chronic infection - staghorn calculi, matrix calculi
Solitary kidney with obstruction
High-risk occupation (pilots, locomotive drivers, sailors)
Patient's preference

10. Prevention of Recurrence

Stone Type	Prevention
All types	High fluid intake (2-2.5 L/day), reduce animal protein, reduce salt intake
Calcium oxalate	Reduce oxalate-rich foods, potassium citrate, thiazide diuretics (↓ urinary Ca²⁺)
Uric acid	Allopurinol, alkalinise urine (potassium citrate)
Struvite/infection	Complete stone removal + long-term antibiotics (mandatory)
Cystine	Alkalinise urine, D-penicillamine, tiopronin

11. Summary Box (High-Yield MBBS Points)

Most common stone: Calcium oxalate (60-85%)
Most common metabolic abnormality: Hypercalciuria
Investigation of choice: NCCT abdomen
Most common acute presentation: Ureteric colic
SWL introduced by: Christian Chaussy, 1980
Steinstrasse: Complication of SWL; stone fragments lining distal ureter
PCNL for: Stones >2 cm, staghorn calculi, failed SWL
URS for: Mid/distal ureteral stones (procedure of choice)
Staghorn calculi: Infection stones; must be completely cleared; long-term antibiotics after removal
Cystine stones: SWL-resistant (very hard due to disulfide bonds)
Open surgery: <1% of cases in modern era
Emergency decompression: JJ stent or PCN for sepsis with obstruction

Bailey and Love's Short Practice of Surgery, 28th Ed., pp. 1495-1499 | Schwartz's Principles of Surgery, 11th Ed., pp. 1789-1791 | Campbell-Walsh-Wein Urology

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