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Renal Vascular Anomalies

Renal Artery Anomalies

70–85 % of kidneys have a single renal artery arising from the aorta. It usually divides into five segmental arteries, which are end arteries.

Pathology of Renal Artery Anomalies

Anomalies:

Accessory vessels to the upper or lower pole are common (approximately 6 % each). Accessory renal arteries may arise from the aorta, the main renal artery (early branching), or, rarely, from the celiac trunk or superior mesenteric artery (aberrant renal artery).

Fraley Syndrome:

Obstruction of the upper calyx by the upper segmental artery or arteries.

Ureteropelvic Junction Obstruction:

Hydronephrosis caused by an accessory lower-pole artery.

Clinical Features

Most renal vascular variants are asymptomatic and are discovered incidentally on imaging or intraoperatively. They become clinically relevant mainly in the presence of obstruction of the upper calyceal infundibulum (Fraley syndrome) or ureteropelvic junction, causing flank pain, recurrent urinary tract infections, stone formation, and, with longstanding obstruction, impaired function of the affected renal segment.

Diagnosis

Ultrasound may show only indirect signs of an anomaly, such as hydronephrosis, reduced parenchymal thickness, or nephrolithiasis. Doppler ultrasound can identify crossing lower-pole vessels in ureteropelvic junction obstruction. CT angiography or MR angiography is appropriate for detailed anatomic assessment of suspected vascular anomalies. In hydronephrosis, renal scintigraphy demonstrates clinically relevant obstruction; in suspected Fraley syndrome, separate assessment of the upper and lower poles is necessary. Invasive angiography is required only in exceptional cases.

Treatment

Asymptomatic renal vascular variants without obstruction require no treatment. Fraley syndrome can be treated by calicopyelostomy or, in the absence of relevant function, by partial nephrectomy. For hydronephrosis caused by an accessory lower-pole artery, see ureteropelvic junction obstruction.

Renal Vein Anomalies

The right renal vein usually drains directly into the inferior vena cava over a short course. The left renal vein normally passes anterior to the aorta to the inferior vena cava and usually receives the left suprarenal and gonadal veins.

Pathology of Renal Vein Anomalies

• Multiple renal veins, more commonly on the right
• Accessory hilar veins, polar veins, or, rarely, atypical drainage into the inferior vena cava
• Retroaortic left renal vein: venous drainage posterior to the aorta
• Circumaortic left renal vein: anterior and posterior venous limbs around the aorta
• Duplicated inferior vena cava
• Nutcracker syndrome: see there

Clinical Features

Most renal vein variants are asymptomatic and are discovered incidentally on imaging, intraoperatively, or during preoperative assessment. They are clinically important primarily because they complicate surgical anatomy and increase the risk of bleeding.

Diagnosis

Renal vein anomalies are often only partially assessable by ultrasound. Contrast-enhanced CT angiography or MR angiography is appropriate for detailed anatomic assessment.

Treatment

Renal vein variants require no treatment, except for nutcracker syndrome.

References

  Deutsche Version: Fehlbildung der Nierenarterie

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