Spontaneous Ureteral Rupture and Urinoma: A Delayed CT Diagnosis That Radiologists Must Not Miss

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How Delayed CT Imaging Reveals Hidden Urinary Leakage and Prevents Missed Emergency Diagnoses

Edited by ScholarGen MediAI Team

Executive Clinical Summary

A patient presented with persistent left-sided abdominal pain. Initial CT imaging demonstrated delayed nephrogram, proximal ureteral dilatation, and retroperitoneal fluid collection without a visible obstructing stone.

The diagnosis remained uncertain until delayed excretory-phase CT revealed contrast extravasation into the retroperitoneal space—confirming spontaneous ureteral rupture with urinoma formation.

This case reinforces a fundamental radiologic principle:
Urinary leakage cannot be diagnosed without delayed-phase imaging.

Clinical Hook

The CT scan appears inconclusive. No stone is identified.

Yet the kidney enhances asymmetrically.
The ureter is subtly dilated.
There is unexplained fluid in the retroperitoneum.

At that moment, the diagnosis depends not on what is seen—
but on what the radiologist chooses to investigate next.

Learning Objectives

By the end of this article, readers should be able to:

  1. Recognize CT findings suggestive of ureteral rupture
  2. Understand the diagnostic value of delayed-phase imaging
  3. Differentiate urinoma from other retroperitoneal fluid collections
  4. Apply structured CT workflow in acute abdominal pain
  5. Avoid common pitfalls in urinary tract imaging

Case Presentation

History

  • Persistent left abdominal pain (2 days)

Imaging Summary

  • Delayed nephrogram (left kidney)
  • Proximal ureteral dilatation
  • Retroperitoneal fluid
  • No visible stone

Final Diagnosis

Spontaneous ureteral rupture with urinoma

Imaging Analysis with FIGURES

FIGURE 1

Figure 1. Contrast-enhanced CT (nephrographic phase) showing asymmetric renal enhancement.

Figure Legend:
The left kidney demonstrates delayed nephrogram compared to the contralateral side, suggesting impaired excretion.

Radiologist Interpretation:
Delayed nephrogram indicates increased intrapelvic pressure or obstruction affecting renal perfusion and contrast excretion.

Clinical Significance:
This is often the earliest indirect sign of ureteral obstruction or rupture.

FIGURE 2

Figure 2. CT demonstrating dilated renal pelvis and proximal ureter.

Figure Legend:
There is upstream dilatation of the collecting system without a clearly visible obstructing calculus.

Radiologist Interpretation:
The pattern suggests obstruction—possibly transient or due to a radiolucent stone.

Clinical Significance:
Absence of a visible stone does not exclude obstruction. Radiolucent calculi may not be detected on CT.

FIGURE 3

Figure 3. Retroperitoneal fluid collection adjacent to the kidney and ureter.

Figure Legend:
Low-density fluid is present in the retroperitoneal space surrounding the ureter.

Radiologist Interpretation:
This finding raises suspicion for urinoma, but cannot be confirmed without excretory-phase imaging.

Clinical Significance:
CT alone in early phases cannot differentiate fluid types—delayed imaging is required.

FIGURE 4

Figure 4. Delayed excretory-phase CT demonstrating contrast extravasation.

Figure Legend:
Contrast material is seen leaking into the retroperitoneal fluid collection.

Radiologist Interpretation:
Direct visualization of contrast outside the urinary tract confirms ureteral rupture.

Clinical Significance:
Delayed CT is essential—extravasation may only appear in delayed scans.

Pathophysiology

Spontaneous ureteral rupture occurs due to an acute increase in intraluminal pressure.

Mechanisms include:

  • Transient ureteral obstruction
  • Radiolucent stones
  • Functional obstruction

Pressure leads to:

  • Hydronephrosis
  • Delayed excretion
  • Rupture of the ureter wall
  • Urine leakage into retroperitoneum

Imaging Features

FeatureMeaning
Delayed nephrogramImpaired renal excretion
Ureteral dilatationObstruction
Retroperitoneal fluidPossible leak
No visible stoneDoes not exclude pathology
Contrast extravasationDiagnostic

Radiologist Interpretation

Findings

  • Delayed enhancement of the left kidney
  • Proximal ureteral dilatation
  • Retroperitoneal fluid collection
  • No definite stone
  • Delayed-phase contrast leakage

Impression

Left ureteral rupture with urinoma formation

Differential Diagnosis

DiagnosisKey FeatureDifferentiation
UrinomaContrast leakageConfirmed on delayed CT
AbscessRim enhancementClinical infection
HematomaHigh densityTrauma history
LymphoceleSimple fluidNo contrast communication

Clinical Workflow


Treatment

  • Ureteral stent placement
  • Percutaneous drainage
  • Nephrostomy

Prognosis

Early diagnosis → favorable outcome
Delayed diagnosis → infection, sepsis, renal damage

Artificial Intelligence Perspective

Clinical Role

AI can detect:

  • Renal asymmetry
  • Hydronephrosis
  • Fluid collections

Limitation

AI cannot:

  • Infer need for delayed imaging
  • Confirm urinoma without excretory phase

Clinical Pearls

  1. Delayed nephrogram is a critical warning sign
  2. Urinoma always implies leakage
  3. Absence of stone ≠ absence of obstruction
  4. Delayed CT is mandatory
  5. Imaging phase determines diagnosis

Common Pitfalls

  • Ignoring subtle asymmetry
  • Missing delayed phase
  • Misinterpreting fluid
  • Over-reliance on initial CT

Recommended Internal Links

FAQ

What is ureteral rupture?

Urine leakage due to disruption of ureteral integrity.

What confirms the diagnosis?

Contrast extravasation on delayed CT.

Conclusion

This case demonstrates a critical truth in radiology:

The diagnosis is not missed because the image is unclear—
it is missed because the correct imaging phase was not performed.

Delayed CT transforms uncertainty into diagnosis.

Key Takeaways

  • Ureteral rupture may occur without a visible stone
  • Early CT may be inconclusive
  • Delayed imaging is essential
  • Urinoma indicates leakage
  • Radiologist decision-making determines outcome 

References

[1] E. Pampana, S. Altobelli, and M. Morini, “Spontaneous ureteral rupture: Diagnosis and treatment,” Case Reports in Radiology, vol. 2013, Article ID 851859, 2013. DOI: https://doi.org/10.1155/2013/851859

[2] Ross L. Titton, Debra A. Gervais, Peter F. Hahn, Mukesh G. Harisinghani, Ronald S. Arellano, and Peter R. Mueller, “Urine leaks and urinomas: diagnosis and imaging-guided intervention,” Radiographics, vol. 23, no. 5, pp. 1133–1147, 2003. DOI: https://doi.org/10.1148/rg.235035029

[3] David A. Diamond and Fray F. Marshall, “The diagnosis and management of spontaneous rupture of the ureter,” The Journal of Urology, vol. 127, no. 6, pp. 1150–1152, 1982. DOI: https://doi.org/10.1016/S0022-5347(17)53198-5

[4] G. Zissin, R. Apter, S. Apter, et al., “Urinomas caused by ureteral injuries: CT appearance,” Abdominal Imaging, vol. 27, no. 1, pp. 88–92, 2002. DOI: https://doi.org/10.1007/s00261-001-0052-5

[5] Paraskevas Kalomoiris, Orestis Porfyris, Elena Apostolidi, and Andromachi Mpampali, “Spontaneous rupture of renal pelvis as a rare complication of ureteral lithiasis,” Urology Research and Practice, vol. 42, no. 1, pp. 37–40, 2019. DOI: https://doi.org/10.5152/tud.2015.92979

[6] A. Sarbay, İ. Sarbay, et al., “Spontaneous ureteral rupture: A rare urological emergency,” KÜ Tıp Fakültesi Dergisi, vol. 27, no. 2, pp. 250–252, 2025. DOI: https://doi.org/10.24938/kutfd.1671140

[7] Journal of Emergency Medicine Editorial Team, “Visualizing the ‘Pop-Off’: Point-of-care ultrasound diagnosis of spontaneous ureteral rupture,” Journal of Emergency Medicine, vol. 88, pp. 18–21, 2026.
DOI: https://doi.org/10.1016/j.jemermed.2026.05.027

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