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Pre-Surgical Workup

Workup

• Imaging: CT provides stone size, location, and density, better than KUB/US for diagnosis
• Urine culture: obtain preop, patients may have unrelated cystitis that requires treatment
• Anticoagulation: can continue for URS, but stop for PCNL and consider stopping for ESWL
• Isolated pyuria: may be due to stone irritation and may not be due to infection
• Frequency/urgency: can be seen with UVJ stone irritation
• Renal function: consider nephrectomy if stone-containing renal unit has < 15% split function
• HU < 500: likely uric acid, confirm not visible on KUB (if HU equivocal), can trial KCit 20mEq BID or NaBicarb 1300mEq BID
• Treatment indications: ureteral stones > 10mm, failed passage after 4-6wks, causing infection, high-risk professions, patient request

Counseling

• Asymptomatic stones: 50% progression at 5yrs, 15% spontaneous passage, surgical intervention 10-20% within 3-4yrs diagnosis
• Staghorn stones: PCNL is preferred treatment, 50% kidneys with staghorn calculi lose function within 2yrs and 11-30% mortality rate without treatment
• Matrix: ESWL doesn't work, best served with PCNL
• Spontaneous passage of ureteral stones: 71% vs 22% for distal vs proximal, 68% for ≤ 5mm, 47% for 6-10mm
• Timing: treat obstructing stones within 4-6 weeks, otherwise can lead to irreversible renal damage, stones that do not pass within 6 weeks are unlikely to pass (< 5%)
• Need for repeat imaging: per Jackman 2021, patients with persistent ureteral stone often have resolution of pain/hydronephrosis, patients may require repeat CT imaging to confirm passage if stone not collected from urine

Medical expulsive therapy

• Indications: most effective for distal ureteral stones > 5mm, but should be offered if distal stone < 10mm and can be offered for proximal stone < 10mm
• Benefits: 29% increased passage rate, decreased time to passage by 2-4d, decreases pain during passage

Factors complicating surgical planning

Renal stone size affecting surgery choice

• < 1cm: ESWL/URS have equivalent stone free rates
• 1cm-2cm: ESWL affected by stone location (lower pole less efficacious) and size, URS affected by stone size, PCNL not affected by stone size
• > 2cm: PCNL 1st choice, ESWL/URS less efficacious with higher need for secondary procedures

Anatomic considerations

• UPJO: can remove stones at time of repair or perform staged procedure
• Calyceal diverticula: rare (0.2-0.6%) and usually asymptomatic, best managed with PCNL
• Horseshoe kidney: 15-20% have kidney stones, can manage based on stone size, ESWL usually less effective due to more complex drainage
• Pelvic kidney: can consider any treatment option, large stones require PCNL or even laparoscopic removal
• Duplicated ureter: uncommon (0.8%), consider retrograde pyelogram
• Ureteral stricture: consider stenting or balloon dilation
• Solitary kidney: consider prophylactic treatment of asymptomatic stones
• Urinary diversion: antegrade approach usually best, PCNL stone free rates 75-88%
• Transplant kidney: prophylactic treatment recommended as lack of innervation will lead to lack of presenting obstructing symptoms

Lower pole location complicates surgeries

• Surgical choice: mainly affects ESWL planning, no effect on PCNL (may be easier), improving URS technology is decreasing issues with lower pole stone treatment
• Imaging findings: assess infundibulopelvic angle, infundibular length, infundibular width
• Dust vs fragment: less likely to spontaneously pass after fragmentation

Emergent Drainage

Criteria for emergent/urgent stent/PCN

• Evidence of infection: fever, leukocytosis, UA with bacteria/WBC
• All renal units blocked: bilateral stones, or unilateral stone in solitary kidney
• Uncontrolled pain/nausea: patient unable to remain home on PO meds
• Hydronephrosis: prolonged or severe unilateral obstruction

Should a patient undergo PCN or stent?

• Pearle 1998: only RCT in literature, no difference in outcomes
• PCN benefits: higher spontaneous stone passage rate, no anatomic restrictions (stricture, finding UO), patients report better pain tolerance, don't actually mind bag as much, better drainage with larger/multiple stones
• Stent benefits: no need to hold anticoagulation
• Bottom line: PCN outperforms stent in all parameters (including patient satisfaction), but stent should usually be attempted if IR is unwilling or unable

Follow-Up

After surgery

• Labs: can obtain 24hr urine once surgery completed and stent/PCN removed
• postop ureteral obstruction with silent hydronephrosis occurs in ~2%, renal US 4-6 weeks after stent removal recommended for all patients, also obtain KUB to rule out residual fragments
• Residual fragment management: fragments > 4mm have high risk of further growth (30-40% will grow by 3-6yr), pain, and requiring additional treatments (10-30%), higher risk with infection stones, should offer repeat PCNL/URS

Long-term

• Labs: repeat 24hr urine 6mo after initial assessment to check for improvements, then consider checking on annual basis to assess for adherence.
• Imaging: no clear evidence for long term screening, but most recommend annual KUB + renal US to assess for stone formation/growth and silent hydronephrosis.