GENITOURINARY IMAGING: Collecting System, Ureter, Bladder
Case Author: Rupan Sanyal, MD, University of Alabama at Birmingham
History
40-year-old man with chronic right flank pain.
Imaging Findings
Axial contrast-enhanced CT image (A) shows severe dilatation of the right renal collecting system. Axial CT image (B) caudal to A shows an enhancing tubular structure (arrowheads) coursing along the posterior aspect of the severely dilated most proximal ureter (arrows). Axial CT image (C) immediately below the tubular structure shows a normal-caliber ureter (arrow). Coronal CT image (D) depicts the relation between the enhancing tubular structure (arrows) and the dilated collecting system.
Diagnosis
Ureteropelvic junction obstruction due to crossing vessel
Teaching Points
Crossing vessels can cause ureteropelvic junction (UPJ) obstruction and exacerbate obstruction caused by intrinsic defects in the musculature. Arterial and venous phase CT images depict crossing vessels.
Awareness of any crossing vessel and its location in relation to the collecting system is important for the surgeon to prevent complications of UPJ surgery, including hemorrhage and pseudoaneurysm formation.
In the presence of crossing vessels, minimally invasive endoscopic UPJ obstruction surgery is associated with a higher rate of failure and complications than open surgical repair owing to lack of visualization of the vessels during the minimally invasive procedure.
Adults with UPJ obstruction can present with acute renal colic or chronic back pain. The pain may be correlated with periods of increased fluid intake or ingestion of a food with diuretic properties, prompting a Dietl crisis (recurrent attacks of radiating pain in the costovertebral angle accompanied by nausea, vomiting, tachycardia, and hypotension due to intermittent UPJ obstruction).
Acquired stenosis of the UPJ can result from upper tract infection, stones, trauma (e.g., instrumentation), and ischemia, all of which can cause reactive fibrosis and annular stricture.
UPJ obstruction can also be caused by malignant tumors.
Suggested Reading
Khaira HS, Platt JF, Cohan RH, Wolf JS, Faerber GJ. Helical computed tomography for identification of crossing vessels in ureteropelvic junction obstruction—comparison with operative findings. Urology 2003; 62:35–39
Lawler LP, Jarret TW, Corl FM, Fishman EK. Adult ureteropelvic junction obstruction: insights with threedimensional multi-detector row CT. RadioGraphics 2005; 25:121–134
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