Clinical Report: Ureteral obstruction linked to degenerative sacroiliitis

Overview

A case report describes a 77-year-old woman with chronic back pain and no urinary symptoms whose imaging showed right ureteral entrapment at a severely degenerated sacroiliac joint, causing hydronephrosis and markedly delayed contrast excretion. Given her age, chronic obstruction, and relatively stable renal function, she was managed conservatively; ultrasound at 3 months showed no significant progression of hydronephrosis. The single case and limited follow-up do not establish long-term outcomes.

Background

Ureteral entrapment at the sacroiliac joint is exceptionally uncommon and may present as otherwise unexplained hydronephrosis. In this case, the patient had no hematuria, dysuria, or change in voiding frequency, and ultrasound showed only mild right hydronephrosis with upper ureteral dilation. CT intravenous pyelography localized the obstruction to an abrupt ureteral caliber change at the right sacroiliac joint, where advanced degenerative changes were present. The authors described this as the third reported nontraumatic clinical case.

Data Highlights

Key Findings

• CT showed the right ureter adherent at the sacroiliac joint, with an abrupt caliber change and narrowing immediately distal to the joint.
• No calculus, enhancing mass, extrinsic compression, or surrounding fibrosis was identified to explain the obstruction.
• The right sacroiliac joint had advanced degenerative changes, including lytic-sclerotic margins and reduced joint space, more pronounced on the right.
• Delayed persistent enhancement of the right kidney and contrast excretion at 10–12 hours were reported alongside the obstructive findings.
• Grade 3 retrograde kinking of the proximal ureter at L3–L4 was considered a benign consequence of ureteral mobility, not the cause of obstruction; the authors attributed urinary tract dilation to the downstream narrowing at the sacroiliac joint.
• The patient declined a recommended renal functional scan and underwent close urologic surveillance; the authors noted that the single-patient report, absent functional scan, and 3-month follow-up limit conclusions about long-term renal outcomes.

Clinical Implications

The authors state that nontraumatic ureteral entrapment at the sacroiliac joint may be considered when hydronephrosis has no identified cause, particularly when degenerative joint changes are present, and emphasize tracing the ureter across the joint on imaging. In this patient, conservative management with periodic renal ultrasonography was followed by no significant progression at 3 months, but the report provides limited evidence about longer-term outcomes.

Conclusion

This case identifies degenerative sacroiliitis as the reported cause of focal ureteral entrapment and obstructive uropathy in an older woman without urinary symptoms. The rarity of the condition and limited follow-up constrain conclusions about its natural history and management.

Related Resources & Content

1. Dave R, et al., Radiology Case Reports, 2026 — Nontraumatic unilateral ureteral entrapment at the sacroiliac joint: A rare cause of obstructive uropathy
2. Clinical Rheumatology, 2026 — Renal osteodystrophy with near-complete bilateral sacroiliac ankylosis: a bat-like pelvic configuration on CT
3. Frontiers in Immunology, 2026 — Case Series: Uncommon Fibro-Inflammatory and Proliferative Disorders Identified in Ureteral Obstruction – Analysis of Four Cases
4. Frontiers in Medicine, 2026 — Case Report: Spontaneous Dissection of the Renal Pelvis and Ureter
5. Factors Associated with Septic Shock in Cases of Obstructive Acute Pyelonephritis
6. Nontraumatic unilateral ureteral entrapment at the sacroiliac joint: A rare cause of obstructive uropathy
7. Renal osteodystrophy with near-complete bilateral sacroiliac ankylosis: a bat-like pelvic configuration on CT
8. Case Series: Uncommon Fibro-Inflammatory and Proliferative Disorders Identified in Ureteral Obstruction – Analysis of Four Cases
9. Case Report: Spontaneous Dissection of the Renal Pelvis and Ureter
10. Nontraumatic unilateral ureteral entrapment at the sacroiliac joint: A rare cause of obstructive uropathy - ScienceDirect
11. Guidelines - EAU Guidelines on Urolithiasis - Uroweb
12. Revised 2019