Circumaortic renal collar

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Circumaortic renal collar Rathod K, Ahmed N, Raut A

Department of Radiology, King Edward VII Memorial Hospital, Parel, Mumbai-400 012, India Correspondence: Krantikumar Rathod, MD E-mail: krantikumarrathod @hotmail.com

Received

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50-year-old female prospective renal donor was referred for preoperative angiography. Intravenous urogram and Technetium Tc-99m Diethylenetriamine Pentaacetic Acid (DTPA) renal scan were unremarkable. Abdominal aortogram and bilateral selective renal angiogram showed normal arterial anatomy. The right kidney was drained by a single renal vein. However, the left kidney was drained by two renal veins that opened into the inferior vena cava (Figure 1). Circumaortic renal vein collar was suspected. Computerised tomographic (CT) scan and CT angiography of abdomen were performed to further delineate the spatial relationship of the left renal veins to the aorta. One of the left renal veins passed anterior to the aorta and posterior to the superior mesenteric artery (Figure 2), and another one i.e. the posterior division coursed inferiorly and medially behind the aorta (Figur e 3) to reach the inferior vena cava forming the left renal vein collar around the aorta (Figure 4).

: 03-07-03

Review completed : 02-08-03 Accepted : 29-09-03

Discussion

PubMed ID : 15048008 J Postgrad Med 2004;50:77-78

Circumaortic renal collar is a rare anomaly involving the left renal vein which has two components,

The occurrence of the circumaortic renal collar can be explained on the basis of embryological development. The primary venous drainage prior to the sixth week is through the posterior cardinal veins.3 These are replaced by the eighth week

at the renal level by four longitudinal channels, the paired supracardinal veins which lie on a plane posterior to the aorta and the paired subcardinal veins which lie at a plane anterior to the aorta.3 There are rich anastomotic communications between the supracardinal-subcardinal, intersupracar dinal and intersubcardinal channels which form a plexus or a collar of veins around the aorta. Paired embryonic vessels on each side unite the kidneys with the right and left suprasubcardinal anastomoses.3 The retroaortic components normally atrophy leaving a preaortic left renal vein. When the reverse occurs, the left renal vein is retroaortic. With the persistence of the entire ring, permanent channels will be found both anterior and pos-

Figure 1: Venous phase of the left renal angiogram shows double renal veins (arrows) draining in the inferior vena cava

Figure 2: Contrast-enhanced CT abdomen reveals one renal vein passing between the aorta and the superior mesenteric artery (white arrow)

one anterior and another posterior to the aorta. The reported incidence is 2%-17% in autopsy studies 1 and 1%-11% in imaging literature.1 It is a potentially hazardous anomaly as failure to recognise the dorsal component during surgery may lead to haemorrhage.2 Ther e have been reports of accidental disruption of the posterior component of the left renal vein leading to haemorrhage and death.2

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Figure 3: Contrast-enhanced CT abdomen showing retroaortic lef t renal vein (black arrow) joining inferior vena cava

terior to the aorta.4 Multidetector CT angiography is highly accurate for detecting vascular anomalies and providing anatomical information for laparoscopic living donor nephrectomy.5 MR angiography is another important modality for the preoperative evaluation of living kidney donors.5 Recent studies of gadolinium-enhanced MR angiography have shown that it has high rates of accuracy and is comparable to conventional angiography and CT angiography in the evaluation of living kidney donors for nephrectomy.5 MR imaging has the additional advantage of avoiding ionizing radiation and potentially nephrotoxic con-




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Figure 4: 3-D reconstr uction showing anatomical relation of the left renal collar with respect to the aorta (both renal veins are indicated by arrows)

trast agents.5 References 1.

2. 3. 4. 5.

Beckmann CF, Abrams HL . Renal venography: Anatomy, technique, applications: Analysis of 132 renograms and review of literature. Cardiovasc Intervent Radiol 1980;3:45-70. Brener BJ, Darling RC, Frederick PL, Linton RR. Major venous anomalies complicating abdominal aortic surgery. Arch Surg 1974;108:159-65. Arey LB. Developmental anatomy. 6th ed. Philadelphia:W. B Saunders Company; 1954 p. 382-5. Mity HA. Circumaortic renal collar, a potentially hazardous anomaly of left renal vein. AJR Am J Roentgenol. 1975;125:307-10. Kawamoto S, Montgomery RA, L awler LP, Horton KM, Elliot K . F ishman. Multidetector CT Angiography for Preoperative Evaluation of Living Laparoscopic Kidney Donors. AJR Am J Roentgenol. 2003;180:1633-8.

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