A rare case report described significant obstructive uropathy associated with nontraumatic ureteral entrapment at the sacroiliac joint in a 77-year-old woman with chronic lower back pain but no urinary symptoms.
The patient reported no hematuria, dysuria, or changes in voiding frequency. Examination revealed tenderness over the sacroiliac joint. Ultrasonography showed mild right-sided hydronephrosis with dilation of the upper ureter. The researchers described the patient's renal function as relatively stable, and routine urine microscopy showed no significant abnormalities. The patient subsequently underwent contrast-enhanced computed tomography (CT) intravenous pyelography to determine the cause of the hydronephrosis.
CT intravenous pyelography included noncontrast, nephrographic, excretory, and prolonged delayed imaging, with the final images obtained 10 to 12 hours following contrast administration. Imaging showed mild-to-moderate right hydronephrosis with mild cortical thinning and mild-to-moderate hydroureter extending to the right sacroiliac joint. At the joint, the ureter appeared adherent, with an abrupt caliber change and narrowing immediately distal to the joint. No intraluminal calculus, enhancing mass, extrinsic compression, or surrounding fibrosis was identified to explain the obstruction.
The sacroiliac joint showed advanced degenerative changes, including bilateral lytic-sclerotic margins and reduced joint space, which were more pronounced on the right. The right kidney demonstrated delayed, persistent enhancement, with contrast excretion markedly delayed until 10 to 12 hours following injection. The imaging findings were consistent with nontraumatic right ureteral entrapment at the sacroiliac joint secondary to chronic degenerative sacroiliitis, resulting in significant obstructive uropathy.
A secondary imaging finding was grade 3 severe retrograde kinking of the proximal ureter at the L3-L4 level. The researchers considered the kinking a benign physiologic consequence of ureteral mobility rather than the source of the obstruction because it did not cause mechanical obstruction or proximal hydroureteronephrosis. Instead, the urinary tract dilation was attributed to the downstream caliber change at the right sacroiliac joint.
Researchers described the case as the third nontraumatic clinical report of ureteral entrapment at the sacroiliac joint. Previously reported cases included traumatic entrapment following pelvic injury and nontraumatic entrapment associated with joint abnormalities.
The 2 previously reported nontraumatic clinical cases were managed with interventions. One patient underwent percutaneous nephrostomy because of renal impairment, whereas another underwent ureteral excision and end-to-end anastomosis. In contrast, the current patient was managed conservatively because of her advanced age, chronic obstruction, and relatively stable renal function. She declined a recommended renal functional scan and was placed under close urologic surveillance with periodic renal ultrasonography. At 3-month follow-up, ultrasonography showed no significant progression of hydronephrosis.
The single-patient nature of the report, absence of a completed renal functional scan, and limited 3-month imaging follow-up restrict interpretation of the findings and provide little evidence about long-term renal outcomes following conservative management.
The findings suggest that nontraumatic ureteral entrapment at the sacroiliac joint may warrant consideration when hydronephrosis has no identified cause, particularly in patients with degenerative joint changes. The researchers emphasized tracing the course of the ureter as it crosses the degenerative joint space on imaging. “Early recognition of this entity is essential to ensure timely, appropriate management and to avoid unnecessary invasive procedures in the elderly population,” wrote lead study author Rushikesh Dave, MBBS, of the Department of Radiognosis, Sardar Vallabhbhai Patel Institute of Medical Science and Research, Smt. N.H.L. Municipal Medical College, Ahmedabad, India, and colleagues.
The authors reported no competing interests.
Source: Radiology Case Reports
