What are the best techniques and guidelines for treating calyceal diverticulum calculus (kidney stone in a calyceal diverticulum)?

Management of Calyceal Diverticulum Calculus

Percutaneous nephrolithotomy (PNL) with direct puncture into the diverticulum and simultaneous fulguration of the diverticular cavity is the primary treatment approach for symptomatic calyceal diverticulum calculi, achieving stone-free rates of 87.5% and complete symptom resolution. 1

Treatment Algorithm Based on Stone and Diverticulum Characteristics

First-Line Treatment: Percutaneous Nephrolithotomy (PNL)

PNL should be the primary approach for most patients with calyceal diverticulum calculi because ESWL monotherapy achieves stone-free status in only 4% of cases, while PNL achieves 87.5% stone-free rates. 1

Technical Approach for PNL:

• Direct puncture into the stone-containing diverticulum is preferred over accessing through an adjacent calyx, as this provides optimal stone clearance and allows complete treatment in a single stage. 1

• Perform simultaneous fulguration of the diverticular lining and infundibulum using a resectoscope with rollerball electrode or electrocautery after stone removal, as this achieves complete obliteration of the diverticulum in all treated patients. 1, 2

• Use flexible nephroscopy with holmium:YAG laser or electrohydraulic lithotripsy for stone fragmentation, followed by fragment removal with flexible instruments. 3

• Stone fragmentation can be performed with ultrasonic or pneumatic lithotripsy using rigid nephroscopy, supplemented by flexible nephroscopy for stones not accessible with the rigid scope. 3

Limited Role for ESWL: Highly Selected Cases Only

ESWL should only be considered for patients with small stones (<1.5 cm) in diverticula with radiographically patent diverticular necks, but even in this selected population, only 58% achieve initial stone-free status. 4

When ESWL May Be Attempted:

• Stone burden less than 1.5 cm 4
• Clearly patent diverticular neck on imaging 4
• Patient preference for less invasive approach as initial trial 5

Critical Limitations of ESWL:

• Recurrent infection occurs in 67% of patients with pre-existing infection, especially when residual calculi remain. 4
• Only 36% of patients become asymptomatic with ESWL alone, and most eventually require PNL for definitive treatment. 1
• If ESWL fails (residual stones with persistent symptoms), proceed directly to PNL rather than repeated ESWL attempts. 5

Alternative Approach: Laparoscopic Treatment

Laparoscopic excision of the diverticulum is indicated when the anterior location precludes percutaneous access and the stone burden or stenotic orifice makes ESWL unsuitable. 6

• This approach allows definitive treatment with minimal morbidity and return to normal activity within 2 weeks. 6
• Consider this when percutaneous puncture fails or is anatomically unfavorable. 5

Technical Considerations for PNL

Access Strategy:

• Upper pole entry typically provides access to the majority of the collecting system and may allow complete stone removal through one site. 3
• Multiple access sites (two or more) may be required when collecting system anatomy is complex. 3
• Tract dilation to 24-30 French using balloon or coaxial dilators is standard. 3

Intraoperative Management:

• Use fluoroscopic or ultrasound guidance for guidewire placement into the kidney and down the ureter. 3
• Sterile saline irrigation throughout the procedure. 3
• Direct visualization of the collecting system allows identification and removal of small fragments that would be missed on imaging. 3

Postoperative Drainage:

• Historically, 20-24 French nephrostomy tubes were placed, though some surgeons now use smaller tubes or internalized ureteral stents without nephrostomy tubes. 3
• The tract can be kept open indefinitely for repeated inspections if needed. 3

Expected Outcomes and Recovery

Stone-Free Rates:

• PNL: 87.5% complete stone-free rate 1
• ESWL monotherapy: 4% stone-free rate 1
• ESWL in selected patients: 58% initial stone-free rate 4

Symptom Resolution:

• All patients managed with PNL become symptom-free 1
• ESWL provides long-term pain relief in 86% of patients with flank pain, often independent of stone-free status 4

Hospitalization and Recovery:

• Hospital stay ranges from 1-5 days depending on need for secondary procedures and patient comorbidities. 3
• Most patients resume normal activities 1-2 weeks after removal of all drainage tubes. 3

Common Pitfalls and How to Avoid Them

The most critical error is attempting ESWL monotherapy without proper patient selection, leading to treatment failure, persistent symptoms, and recurrent infections. 1

• Do not use ESWL for stones >1.5 cm or stenotic diverticular necks as failure is nearly certain. 4
• Do not perform multiple ESWL sessions for persistent stones—convert to PNL after first ESWL failure. 1
• Always perform diverticular fulguration during PNL to prevent recurrence; all patients without fulguration risk persistent diverticulum. 1
• Recurrent stones after ESWL are uncommon (documented in only 1 of 13 patients at mean 23.8 months follow-up), but recurrent infection remains problematic. 4

Management of Treatment Failures

When percutaneous puncture fails (occurs in approximately 19% of attempts), proceed to open surgical excision via lumbotomy. 5

Morbidity from PNL includes postoperative bleeding (23% of cases) and high fever (8% of cases), but these complications are manageable and do not contraindicate the procedure. 5