Giant Neobladder Stone 14 Years After Radical Cystectomy: CT Findings, Stone Composition, and Clinical Lessons
What Is a Neobladder Stone?
A neobladder stone is a urinary calculus that forms within a surgically created reservoir after bladder removal. In patients with an orthotopic ileal neobladder, stone formation may be associated with urinary stasis, intestinal mucus, bacterial colonization, metabolic changes, or retained surgical material. CT helps identify the stone, define its location and size, and evaluate the remaining urinary tract for additional calculi or obstruction.
Clinical Case: Flank Pain and Urinary Retention 14 Years After Bladder Cancer Surgery
A 66-year-old man presented to the emergency department with a three-day history of left flank pain and urinary retention. Approximately 14 years earlier, he had undergone radical cystectomy for invasive bladder cancer, followed by construction of an orthotopic neobladder using an intestinal segment.
Physical examination demonstrated left flank tenderness.
Abdominal and pelvic CT revealed two distinct urinary calculi:
A left proximal ureteral calculus
A very large calculus within the neobladder
The left ureteral stone was accessed through percutaneous nephrostomy with antegrade ureteroscopic assistance and removed using laser lithotripsy. The neobladder calculus was removed by open cystolithotomy.
The extracted stone was egg-shaped and measured 12 × 9.5 × 7.5 cm, with a weight of 770 g. Stone analysis demonstrated:
Stone component | Proportion |
|---|---|
Calcium phosphate | 80% |
Struvite | 20% |
The patient had no reported postoperative complications and continued follow-up for recurrence monitoring.
Clinical takeaway: In a patient with prior radical cystectomy and urinary diversion, flank pain or urinary retention should prompt evaluation of both the upper urinary tract and the reconstructed urinary reservoir.
Figure 1. CT Demonstration of a Giant Neobladder Calculus
Coronal and sagittal abdominal and pelvic CT images demonstrate a very large calculus within the orthotopic neobladder and a separate left proximal ureteral calculus. Multiplanar review helps establish the location of each stone and its relationship to the reconstructed urinary anatomy.
Abdominal CT showing a giant neobladder stone and left proximal ureteral calculus after radical cystectomy
Why Can Stones Form in an Orthotopic Neobladder?
An orthotopic neobladder is constructed from an intestinal segment and connected to the native urethra, allowing patients to store urine and void through a more physiologic route. However, intestinal tissue retains biological characteristics that differ from those of a native urinary bladder.
Stone formation is multifactorial. Several mechanisms are relevant to this case and to the broader clinical management of patients with urinary diversion.
1. Urinary Stasis
Incomplete emptying can increase the time available for urinary crystals to aggregate and grow. Reservoir configuration, voiding function, and outlet resistance may influence residual urine volume.
Urinary retention is therefore both a presenting symptom and a potential contributor to stone formation. Imaging should assess the degree of reservoir distention and evaluate the upper urinary tract for associated dilation when present.
2. Intestinal Mucus
Intestinal mucosa continues to produce mucus after incorporation into a urinary reservoir. Mucus may contribute to debris accumulation and provide a substrate for crystal aggregation.
The contribution of mucus varies between patients. Its presence should be considered as part of the overall risk environment rather than assumed to be the sole cause of a particular calculus.
3. Bacterial Colonization
Urinary reservoirs constructed from bowel may be subject to chronic or recurrent bacterial colonization. Urease-producing organisms can increase urinary pH and promote precipitation of infection-related minerals, including struvite.
In this case, struvite accounted for 20% of the stone composition. This finding is compatible with an infection-related contribution, but it does not independently identify a specific organism or establish when infection occurred.
4. Metabolic Changes Associated With Intestinal Urinary Diversion
Use of an intestinal segment for urinary diversion can alter acid-base and urinary solute handling. Potential metabolic contributors described in the clinical literature include metabolic acidosis, hyperoxaluria, hypercalciuria, and hypocitraturia. These abnormalities may contribute to urinary stone risk in selected patients. [1,2]
The case description identifies persistent bicarbonate loss and hyperoxaluria among possible mechanisms. These should be interpreted as risk factors—not as individually confirmed abnormalities in this patient.
5. Retained or Nonabsorbable Surgical Material
Nonabsorbable material used during reconstruction may act as a nidus for stone formation when exposed to urine. Surgical clips or staples may be relevant in some patients, but their presence should not be assumed unless documented in the operative history or demonstrated on imaging.
CT Interpretation: More Than Detecting a Stone
CT is valuable because it can answer several clinically distinct questions in a patient with a reconstructed urinary reservoir.
Confirm the Location
The radiologist should determine whether a calculus is located in the neobladder, ureter, renal collecting system, or more than one site.
This distinction matters because patients may have simultaneous reservoir and upper urinary tract stone disease, as demonstrated in this case.
Define the Stone Burden
A giant calculus may occupy a substantial portion of the neobladder. Multiplanar images help establish its dimensions and relationship to the reservoir.
The reported calculus measured 12 × 9.5 × 7.5 cm. Its exceptionally large size is a major clinical feature, but size alone does not establish mineral composition.
Evaluate for Obstruction
The left proximal ureteral calculus was a separate finding from the neobladder stone. CT interpretation should therefore include the kidneys and ureters rather than stopping after identifying the dominant reservoir calculus.
When present, hydronephrosis, hydroureter, or other signs of obstruction should be described. The case establishes a left proximal ureteral calculus but does not provide additional quantified obstruction measurements.
Recognize the Reconstructed Anatomy
After radical cystectomy, the expected anatomy is altered. Familiarity with the surgical reconstruction helps the reader identify the urinary reservoir, its connection to the urethra, and the relevant upper urinary tract structures.
Practical reporting principle: Describe stone location, size, number, associated urinary tract findings, and evidence of obstruction. Avoid inferring infection, metabolic abnormalities, or exact stone composition from CT appearance alone.
Stone Composition: Why the Predominant Component Matters
Figure 2. Neobladder Stone
The extracted calculus was composed of 80% calcium phosphate and 20% struvite. The predominant component was therefore calcium phosphate.
Calcium phosphate stone formation is associated with urinary conditions that favor crystal precipitation, including relatively alkaline urine. Struvite is associated with infection-related stone formation in the setting of urease-producing bacteria.
The mixed composition suggests that more than one mechanism may have contributed. However, stone analysis does not independently establish the patient’s urinary pH, bacterial culture results, or metabolic profile at the time of stone formation.
What CT Can—and Cannot—Tell Us
CT can identify and localize urinary calculi and assess their burden. However, conventional CT appearance should not be treated as a definitive substitute for stone analysis when precise mineral composition is clinically important.
In this case, the composition was established by analysis of the extracted calculus, not simply by imaging.
Management: Treating the Upper Tract and the Reservoir
The patient required treatment of two anatomically separate stones.
Left Proximal Ureteral Calculus
The left ureteral stone was accessed through percutaneous nephrostomy with antegrade ureteroscopic assistance and removed using laser lithotripsy.
Giant Neobladder Calculus
The neobladder stone was removed by open cystolithotomy. Its very large dimensions and weight—12 × 9.5 × 7.5 cm and 770 g—are central features of this case.
The patient had no reported postoperative complications and continued monitoring for recurrence.
Why Follow-Up Remains Important
Removal of a calculus addresses the existing stone burden, but it may not eliminate the conditions that enabled stone formation. Follow-up may include assessment of voiding and residual urine, evaluation for recurrent infection when indicated, and review of urinary or metabolic risk factors.
The case reports ongoing recurrence monitoring but does not specify a particular surveillance schedule or laboratory protocol.
Diagnostic Risk Perspective: Avoiding a Narrow CT Search
A patient with a history of bladder cancer surgery may present with symptoms that appear to point toward a single urinary tract location. This case demonstrates why a complete review is essential.
A focused search for an upper urinary tract calculus could miss a large reservoir stone. Conversely, attention to a dramatic neobladder calculus should not distract from a separate ureteral stone.
This is a system-level imaging lesson:
Review the kidneys and ureters as well as the reconstructed reservoir.
Confirm the altered postoperative anatomy.
Search for multiple sites of stone disease.
Describe obstruction separately from stone presence.
Avoid assuming that the largest or most conspicuous calculus explains every symptom.
Clinical Lessons Beyond This Case
Urinary diversion does not eliminate stone risk. An orthotopic neobladder can develop calculi years after reconstruction.
Symptoms may reflect more than one stone. Flank pain and urinary retention should prompt evaluation of both the upper tract and reservoir.
CT is an anatomic problem-solving tool. Location, burden, and associated obstruction are essential reporting elements.
Stone composition requires appropriate confirmation. In this case, analysis showed 80% calcium phosphate and 20% struvite.
Prevention requires attention to underlying conditions. Urinary stasis, mucus, bacterial colonization, metabolic changes, and surgical material may all be relevant.
Long-term follow-up matters. Stone removal does not necessarily eliminate the factors that promote recurrence.
Knowledge Check
A 66-year-old man with a history of radical cystectomy and orthotopic neobladder construction presents with flank pain and urinary retention. CT demonstrates a giant neobladder calculus. The extracted stone is composed of 80% calcium phosphate and 20% struvite. What is its predominant component?
A. Struvite
B. Uric acid
C. Calcium oxalate
D. Calcium phosphate
E. Cystine
Correct answer: D. Calcium phosphate
Explanation: Calcium phosphate accounted for 80% of the analyzed calculus, making it the predominant component. Struvite represented the remaining 20%.
Frequently Asked Questions
Can a neobladder stone form many years after radical cystectomy?
Yes. This case describes a giant calculus identified approximately 12 years after radical cystectomy and orthotopic neobladder construction. Urinary diversion complications may arise long after the initial operation. [1,3]
Why are intestinal urinary reservoirs susceptible to stone formation?
Potential contributors include urinary stasis, intestinal mucus, bacterial colonization, metabolic changes, and retained surgical material. Their relative importance varies between patients. [1,2]
Does CT determine the exact composition of a neobladder stone?
CT is highly useful for detecting and localizing calculi, but exact mineral composition should not be assumed from conventional imaging alone. In this case, stone analysis established the composition.
What was the composition of the giant calculus in this case?
The calculus contained 80% calcium phosphate and 20% struvite.
What is the main imaging lesson?
Evaluate the entire urinary tract, including the kidneys, ureters, and reconstructed reservoir. Multiple stones may coexist, and the dominant finding may not explain every symptom.
Continue Learning
[Internal Link Placeholder] CT Evaluation of Urinary Calculi: Location, Burden, and Obstruction
[Internal Link Placeholder] Imaging After Radical Cystectomy: Recognizing Urinary Diversion Anatomy
Medical Disclaimer
This article is intended for medical education and professional discussion. It does not replace individualized clinical assessment, radiologic interpretation, or consultation with the treating urology team. Management decisions should be based on the patient’s clinical condition, reconstructed anatomy, imaging findings, and relevant laboratory results.
References
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[5] H. Kubota, S. Takahashi, S. Monzawa, N. Yuasa, T. Endo, and T. Miura et al., “Pictorial review of orthotopic neobladder reconstruction: Indication, normal postsurgical anatomy, and complications,” Abdominal Radiology, vol. 41, no. 2, pp. 356–367, 2016.
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[7] A. Terai, T. Ueda, Y. Kakehi, T. Terachi, Y. Arai, and Y. Okada et al., “Urinary calculi as a late complication of the Indiana continent urinary diversion: Comparison with the Kock pouch procedure,” The Journal of Urology, vol. 155, no. 1, pp. 66–68, 1996.
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[8] D. Ginsberg, J. L. Huffman, G. Lieskovsky, S. Boyd, and D. G. Skinner, “Urinary tract stones: A complication of the Kock pouch continent urinary diversion,” The Journal of Urology, vol. 145, no. 5, pp. 956–959, 1991. doi: 10.1016/S0022-5347(17)38499-9
[9] European Association of Urology, “EAU Guidelines on Urolithiasis: Bladder Stones—Urinary Diversion.” [Online]. Available: https://uroweb.org/guidelines/urolithiasis/chapter/bladder-stones
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