Case Report: Dual giant neobladder stones weighing 950 grams following 18-year loss to follow-up: surgical management and prevention strategies.

Background: Neobladder urolithiasis represents a significant long-term complication following radical cystectomy with orthotopic reconstruction, with incidence ranging from 3-9% for ileal neobladders to as high as 43% for Kock pouch configurations. Giant stones are rare and usually result from prolonged gaps in surveillance combined with inadequate preventive measures. Patient presentation: This is a case of a 78-year-old male presenting with progressive lower urinary tract symptoms after 18 years without urological follow-up following radical cystoprostatectomy and ileal neobladder reconstruction for muscle-invasive bladder cancer (pT2N0M0) performed in 2006. He had relocated geographically one year post-surgery and stopped all urological care, never performing self-catheterization or bladder irrigation as instructed. Computed tomography revealed two massive neobladder stones measuring 10×8×6 cm and 9×7×8 cm with 1,300 Hounsfield Units density. Open cystolithotomy successfully removed both calculi with a combined weight of 950 grams in 90 minutes with minimal blood loss of 100 mL and no complications. Stone analysis confirmed a pure struvite-carbonate apatite composition secondary to chronic Proteus mirabilis infection. The patient was discharged on postoperative day 3. Follow-up at 1, 3, 6, and 12 months demonstrated complete symptom resolution, stone-free status on imaging, and stable renal function. However, the patient was subsequently lost to follow-up again after 12 months despite multiple attempts at contact. Conclusions: This case, representing one of the heaviest dual-stone presentations documented in neobladder patients (950g combined weight), demonstrates that complete surgical excision via open cystolithotomy remains the treatment of choice for giant neobladder calculi. The exceptionally prolonged 18-year surveillance gap enabled progressive bilateral stone development, emphasizing the absolute necessity of lifelong structured follow-up programs for all urinary diversion patients. Comprehensive preventive strategies including daily bladder irrigation with 500-1000 mL normal saline, adequate hydration (≥2.5 L daily), aggressive infection control with surveillance cultures every 3-6 months and suppressive antibiotic prophylaxis when indicated, and regular imaging surveillance are essential to prevent such severe complications. Even after prolonged follow-up loss and massive stone development, curative intervention can achieve excellent outcomes when patients subsequently engage with comprehensive preventive protocols, as demonstrated by this patient's stone-free status during the 12-month compliant period.