Incidence of major venous and renal anomalies relevant to aortoiliac surgery as demonstrated by computed tomography.

Preoperative knowledge of the presence of major venous anomalies facilitates the safe performance of aortic surgery. The purpose of the study was to estimate the incidence, as detected by abdominal and pelvic computed tomography (CT), of major venous and renal anomalies related to the abdominal aorta in an adult population. A total of 1822 intravenous contrast-enhanced abdominal and pelvic CT scans done in 1822 patients at two university teaching hospitals were randomly selected and prospectively reviewed (between June 1999 and March 2000) to identify major venous and renal anomalies associated with the abdominal aorta and iliac arteries. An interpreting staff radiologist then indicated on adata sheet whether any of the following anomalies were present or absent: (1) retroaortic left renal vein, (2) circumaortic left renal vein, (3) left-sided inferior vena cava (IVC) without situs inversus, (4) left-sided IVC with situs inversus, (5) duplicate IVC, (6) preaortic confluence of the iliac veins, or (7) horseshoe kidney. The CT scans reviewed had been performed for a wide variety of indications. Thirty-four scans were excluded from the study because either the anomalies we were looking for could not be assessed for technical reasons or the patient had a previous left nephrectomy and therefore assessment of the left renal vein was impossible. From this analysis we found that in an adult population, the prevalence of major venous and renal anomalies related to the abdominal aortaand iliac arteries and detected by CT scan was 5.65%. Prior to aortic surgery, preoperative knowledge of the presence of such anomalies helps with operative planning and may reduce the risk of major venous hemorrhage associated with these anomalies.