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Spectrum of Congenital Anomalies of the Inferior Vena Cava: Cross-sectional Imaging Findings¹

(CME available in print version and on RSNA Link)

¹ From the Department of Radiology, University of Texas Health Science Center, Houston. Presented as a scientific exhibit at the 1998 RSNA scientific assembly. Received March 16, 1999; revision requested May 7 and received July 1; accepted July 8. Address reprint requests to J.E.B., Hermann Imaging and Breast Center, 6410 Fannin, Suite 170, Houston, TX 77030 (e-mail: J.E.Bass@uth.tmc.edu).

View larger version (43K): [in a new window]   Figure 1.   Conceptual framework for development of the IVC. Composite schematic shows the relative positions and interrelationships of the three paired embryonic vessels that contribute to development of the IVC. The pictured veins are not all present simultaneously. Under ordinary circumstances, the prerenal division is formed from union of the hepatic segment (green area), a vitelline vein derivative, and the right subcardinal vein (magenta area). The renal segment is formed from the suprasubcardinal anastomosis (yellow area) and the postsubcardinal anastomosis (light violet area). The infrarenal segment derives from the right supracardinal vein (goldenrod area). The iliac veins form from the posterior cardinal veins (dark violet area). (Adapted and reprinted, with permission, from reference 4.) card  = cardinal, post  = posterior, SMA  = superior mesenteric artery, v  = vein, 1  = intersubcardinal anastomosis, 2  = intersupracardinal anastomosis.

View larger version (29K): [in a new window]   Figure 2a.   Partial malrotation and left IVC in a 49-year-old man. (a) Schematic shows a left IVC terminating at the left renal vein. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) Note the left IVC (arrow) inferior to the renal veins. (c) The left IVC joins the left renal vein (arrow). (d) The left renal vein (arrow) crosses anterior to the aorta in the normal fashion. (e) A normal right-sided prerenal IVC is formed from the confluence of the left (straight arrow) and right (curved arrow) renal veins. Note the increased attenuation of the right renal vein relative to that of the left due to absence of dilution from relatively unenhanced lower-extremity venous return.

View larger version (129K): [in a new window]   Figure 2b.   Partial malrotation and left IVC in a 49-year-old man. (a) Schematic shows a left IVC terminating at the left renal vein. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) Note the left IVC (arrow) inferior to the renal veins. (c) The left IVC joins the left renal vein (arrow). (d) The left renal vein (arrow) crosses anterior to the aorta in the normal fashion. (e) A normal right-sided prerenal IVC is formed from the confluence of the left (straight arrow) and right (curved arrow) renal veins. Note the increased attenuation of the right renal vein relative to that of the left due to absence of dilution from relatively unenhanced lower-extremity venous return.

View larger version (137K): [in a new window]   Figure 2c.   Partial malrotation and left IVC in a 49-year-old man. (a) Schematic shows a left IVC terminating at the left renal vein. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) Note the left IVC (arrow) inferior to the renal veins. (c) The left IVC joins the left renal vein (arrow). (d) The left renal vein (arrow) crosses anterior to the aorta in the normal fashion. (e) A normal right-sided prerenal IVC is formed from the confluence of the left (straight arrow) and right (curved arrow) renal veins. Note the increased attenuation of the right renal vein relative to that of the left due to absence of dilution from relatively unenhanced lower-extremity venous return.

View larger version (136K): [in a new window]   Figure 2d.   Partial malrotation and left IVC in a 49-year-old man. (a) Schematic shows a left IVC terminating at the left renal vein. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) Note the left IVC (arrow) inferior to the renal veins. (c) The left IVC joins the left renal vein (arrow). (d) The left renal vein (arrow) crosses anterior to the aorta in the normal fashion. (e) A normal right-sided prerenal IVC is formed from the confluence of the left (straight arrow) and right (curved arrow) renal veins. Note the increased attenuation of the right renal vein relative to that of the left due to absence of dilution from relatively unenhanced lower-extremity venous return.

View larger version (142K): [in a new window]   Figure 2e.   Partial malrotation and left IVC in a 49-year-old man. (a) Schematic shows a left IVC terminating at the left renal vein. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) Note the left IVC (arrow) inferior to the renal veins. (c) The left IVC joins the left renal vein (arrow). (d) The left renal vein (arrow) crosses anterior to the aorta in the normal fashion. (e) A normal right-sided prerenal IVC is formed from the confluence of the left (straight arrow) and right (curved arrow) renal veins. Note the increased attenuation of the right renal vein relative to that of the left due to absence of dilution from relatively unenhanced lower-extremity venous return.

View larger version (34K): [in a new window]   Figure 3a.   Lymphoma and double IVC in a 53-year-old woman. (a) Schematic shows left and right infrarenal IVCs. The left IVC terminates at the left renal vein. (b) CT scan obtained inferior to the renal veins shows left (straight arrow) and right (curved arrow) IVCs. (c-e) CT scans show the left IVC ending at the confluence with the left renal vein (arrow in c), which crosses anterior to the aorta in the normal fashion (arrow in d) to join a normal prerenal IVC (arrow in e).

View larger version (131K): [in a new window]   Figure 3b.   Lymphoma and double IVC in a 53-year-old woman. (a) Schematic shows left and right infrarenal IVCs. The left IVC terminates at the left renal vein. (b) CT scan obtained inferior to the renal veins shows left (straight arrow) and right (curved arrow) IVCs. (c-e) CT scans show the left IVC ending at the confluence with the left renal vein (arrow in c), which crosses anterior to the aorta in the normal fashion (arrow in d) to join a normal prerenal IVC (arrow in e).

View larger version (130K): [in a new window]   Figure 3c.   Lymphoma and double IVC in a 53-year-old woman. (a) Schematic shows left and right infrarenal IVCs. The left IVC terminates at the left renal vein. (b) CT scan obtained inferior to the renal veins shows left (straight arrow) and right (curved arrow) IVCs. (c-e) CT scans show the left IVC ending at the confluence with the left renal vein (arrow in c), which crosses anterior to the aorta in the normal fashion (arrow in d) to join a normal prerenal IVC (arrow in e).

View larger version (124K): [in a new window]   Figure 3d.   Lymphoma and double IVC in a 53-year-old woman. (a) Schematic shows left and right infrarenal IVCs. The left IVC terminates at the left renal vein. (b) CT scan obtained inferior to the renal veins shows left (straight arrow) and right (curved arrow) IVCs. (c-e) CT scans show the left IVC ending at the confluence with the left renal vein (arrow in c), which crosses anterior to the aorta in the normal fashion (arrow in d) to join a normal prerenal IVC (arrow in e).

View larger version (126K): [in a new window]   Figure 3e.   Lymphoma and double IVC in a 53-year-old woman. (a) Schematic shows left and right infrarenal IVCs. The left IVC terminates at the left renal vein. (b) CT scan obtained inferior to the renal veins shows left (straight arrow) and right (curved arrow) IVCs. (c-e) CT scans show the left IVC ending at the confluence with the left renal vein (arrow in c), which crosses anterior to the aorta in the normal fashion (arrow in d) to join a normal prerenal IVC (arrow in e).

View larger version (33K): [in a new window]   Figure 4a.   Abnormal mediastinum at chest radiography secondary to azygos continuation of the IVC in a 48-year-old man. (a) Schematic shows lack of contiguity between the prerenal segment of the IVC (arrow) and the hepatic segment. The vessel parallel to the aorta under the crus is the azygos vein. (b, c) CT scans obtained at the level of the diaphragmatic crus (b) and the level of the azygos vein arch (c) show the enlarged azygos vein (straight arrow) draining into the superior vena cava (curved arrow in c).

View larger version (101K): [in a new window]   Figure 4b.   Abnormal mediastinum at chest radiography secondary to azygos continuation of the IVC in a 48-year-old man. (a) Schematic shows lack of contiguity between the prerenal segment of the IVC (arrow) and the hepatic segment. The vessel parallel to the aorta under the crus is the azygos vein. (b, c) CT scans obtained at the level of the diaphragmatic crus (b) and the level of the azygos vein arch (c) show the enlarged azygos vein (straight arrow) draining into the superior vena cava (curved arrow in c).

View larger version (94K): [in a new window]   Figure 4c.   Abnormal mediastinum at chest radiography secondary to azygos continuation of the IVC in a 48-year-old man. (a) Schematic shows lack of contiguity between the prerenal segment of the IVC (arrow) and the hepatic segment. The vessel parallel to the aorta under the crus is the azygos vein. (b, c) CT scans obtained at the level of the diaphragmatic crus (b) and the level of the azygos vein arch (c) show the enlarged azygos vein (straight arrow) draining into the superior vena cava (curved arrow in c).

View larger version (39K): [in a new window]   Figure 5a.   Circumaortic left renal vein in a 73-year-old woman. (a) Schematic shows two left renal veins, with the inferior vein crossing posterior to the aorta. (b-e) Contiguous 5-mm-thick CT sections presented from cranial to caudal show the anomaly. (b) The superior left renal vein (arrow) crosses anterior to the aorta. (c-e) The inferior vein (curved arrow) descends approximately 2 cm and receives the left gonadal vein (straight arrow in d) before crossing posterior to the aorta.

View larger version (122K): [in a new window]   Figure 5b.   Circumaortic left renal vein in a 73-year-old woman. (a) Schematic shows two left renal veins, with the inferior vein crossing posterior to the aorta. (b-e) Contiguous 5-mm-thick CT sections presented from cranial to caudal show the anomaly. (b) The superior left renal vein (arrow) crosses anterior to the aorta. (c-e) The inferior vein (curved arrow) descends approximately 2 cm and receives the left gonadal vein (straight arrow in d) before crossing posterior to the aorta.

View larger version (123K): [in a new window]   Figure 5c.   Circumaortic left renal vein in a 73-year-old woman. (a) Schematic shows two left renal veins, with the inferior vein crossing posterior to the aorta. (b-e) Contiguous 5-mm-thick CT sections presented from cranial to caudal show the anomaly. (b) The superior left renal vein (arrow) crosses anterior to the aorta. (c-e) The inferior vein (curved arrow) descends approximately 2 cm and receives the left gonadal vein (straight arrow in d) before crossing posterior to the aorta.

View larger version (124K): [in a new window]   Figure 5d.   Circumaortic left renal vein in a 73-year-old woman. (a) Schematic shows two left renal veins, with the inferior vein crossing posterior to the aorta. (b-e) Contiguous 5-mm-thick CT sections presented from cranial to caudal show the anomaly. (b) The superior left renal vein (arrow) crosses anterior to the aorta. (c-e) The inferior vein (curved arrow) descends approximately 2 cm and receives the left gonadal vein (straight arrow in d) before crossing posterior to the aorta.

View larger version (121K): [in a new window]   Figure 5e.   Circumaortic left renal vein in a 73-year-old woman. (a) Schematic shows two left renal veins, with the inferior vein crossing posterior to the aorta. (b-e) Contiguous 5-mm-thick CT sections presented from cranial to caudal show the anomaly. (b) The superior left renal vein (arrow) crosses anterior to the aorta. (c-e) The inferior vein (curved arrow) descends approximately 2 cm and receives the left gonadal vein (straight arrow in d) before crossing posterior to the aorta.

View larger version (30K): [in a new window]   Figure 6a.   Retroaortic left renal vein in a 27-year-old man. (a) Schematic shows a single left renal vein, which crosses posterior to the aorta. (b, c) CT scans show the left renal vein (arrow) descending to cross posterior to the aorta.

View larger version (130K): [in a new window]   Figure 6b.   Retroaortic left renal vein in a 27-year-old man. (a) Schematic shows a single left renal vein, which crosses posterior to the aorta. (b, c) CT scans show the left renal vein (arrow) descending to cross posterior to the aorta.

View larger version (127K): [in a new window]   Figure 6c.   Retroaortic left renal vein in a 27-year-old man. (a) Schematic shows a single left renal vein, which crosses posterior to the aorta. (b, c) CT scans show the left renal vein (arrow) descending to cross posterior to the aorta.

View larger version (32K): [in a new window]   Figure 7a.   Spinal dysraphism and double IVC with hemiazygos continuation in a 2-year-old boy. (a) Schematic shows failed development of the right prerenal IVC and hemiazygos continuation of the left IVC. (b-e) MR images presented from caudal to cranial show the anomaly. (b) Note the right (straight arrow) and left (curved arrow) IVCs. (c) The right renal vein (arrowhead) descends to receive the right IVC and crosses posterior to the aorta (arrow) to join the left IVC. (d) The left IVC continues cephalad left of the aorta under the diaphragmatic crus as the hemiazygos vein (arrow). (e) In the thorax, the hemiazygos vein (straight arrow) crosses posterior to the aorta (arrowhead) to join a rudimentary azygos vein (curved arrow) approximately 1-2 cm below the carina.

View larger version (99K): [in a new window]   Figure 7b.   Spinal dysraphism and double IVC with hemiazygos continuation in a 2-year-old boy. (a) Schematic shows failed development of the right prerenal IVC and hemiazygos continuation of the left IVC. (b-e) MR images presented from caudal to cranial show the anomaly. (b) Note the right (straight arrow) and left (curved arrow) IVCs. (c) The right renal vein (arrowhead) descends to receive the right IVC and crosses posterior to the aorta (arrow) to join the left IVC. (d) The left IVC continues cephalad left of the aorta under the diaphragmatic crus as the hemiazygos vein (arrow). (e) In the thorax, the hemiazygos vein (straight arrow) crosses posterior to the aorta (arrowhead) to join a rudimentary azygos vein (curved arrow) approximately 1-2 cm below the carina.

View larger version (106K): [in a new window]   Figure 7c.   Spinal dysraphism and double IVC with hemiazygos continuation in a 2-year-old boy. (a) Schematic shows failed development of the right prerenal IVC and hemiazygos continuation of the left IVC. (b-e) MR images presented from caudal to cranial show the anomaly. (b) Note the right (straight arrow) and left (curved arrow) IVCs. (c) The right renal vein (arrowhead) descends to receive the right IVC and crosses posterior to the aorta (arrow) to join the left IVC. (d) The left IVC continues cephalad left of the aorta under the diaphragmatic crus as the hemiazygos vein (arrow). (e) In the thorax, the hemiazygos vein (straight arrow) crosses posterior to the aorta (arrowhead) to join a rudimentary azygos vein (curved arrow) approximately 1-2 cm below the carina.

View larger version (95K): [in a new window]   Figure 7d.   Spinal dysraphism and double IVC with hemiazygos continuation in a 2-year-old boy. (a) Schematic shows failed development of the right prerenal IVC and hemiazygos continuation of the left IVC. (b-e) MR images presented from caudal to cranial show the anomaly. (b) Note the right (straight arrow) and left (curved arrow) IVCs. (c) The right renal vein (arrowhead) descends to receive the right IVC and crosses posterior to the aorta (arrow) to join the left IVC. (d) The left IVC continues cephalad left of the aorta under the diaphragmatic crus as the hemiazygos vein (arrow). (e) In the thorax, the hemiazygos vein (straight arrow) crosses posterior to the aorta (arrowhead) to join a rudimentary azygos vein (curved arrow) approximately 1-2 cm below the carina.

View larger version (98K): [in a new window]   Figure 7e.   Spinal dysraphism and double IVC with hemiazygos continuation in a 2-year-old boy. (a) Schematic shows failed development of the right prerenal IVC and hemiazygos continuation of the left IVC. (b-e) MR images presented from caudal to cranial show the anomaly. (b) Note the right (straight arrow) and left (curved arrow) IVCs. (c) The right renal vein (arrowhead) descends to receive the right IVC and crosses posterior to the aorta (arrow) to join the left IVC. (d) The left IVC continues cephalad left of the aorta under the diaphragmatic crus as the hemiazygos vein (arrow). (e) In the thorax, the hemiazygos vein (straight arrow) crosses posterior to the aorta (arrowhead) to join a rudimentary azygos vein (curved arrow) approximately 1-2 cm below the carina.

View larger version (30K): [in a new window]   Figure 8a.   Double IVC with a retroaortic left renal vein and azygos continuation in a 31-year-old woman. (a) Schematic shows the anomalous venous pattern. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) The right IVC receives the right renal vein (straight arrow). Note the left IVC (curved arrow). (c) The left IVC (arrow) receives the left renal vein. (d) The left renal vein (arrow) crosses posterior to the aorta to join the right IVC. (e) The right IVC continues cephalad as the azygos vein (arrow) within the retrocrural space.

View larger version (113K): [in a new window]   Figure 8b.   Double IVC with a retroaortic left renal vein and azygos continuation in a 31-year-old woman. (a) Schematic shows the anomalous venous pattern. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) The right IVC receives the right renal vein (straight arrow). Note the left IVC (curved arrow). (c) The left IVC (arrow) receives the left renal vein. (d) The left renal vein (arrow) crosses posterior to the aorta to join the right IVC. (e) The right IVC continues cephalad as the azygos vein (arrow) within the retrocrural space.

View larger version (111K): [in a new window]   Figure 8c.   Double IVC with a retroaortic left renal vein and azygos continuation in a 31-year-old woman. (a) Schematic shows the anomalous venous pattern. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) The right IVC receives the right renal vein (straight arrow). Note the left IVC (curved arrow). (c) The left IVC (arrow) receives the left renal vein. (d) The left renal vein (arrow) crosses posterior to the aorta to join the right IVC. (e) The right IVC continues cephalad as the azygos vein (arrow) within the retrocrural space.

View larger version (116K): [in a new window]   Figure 8d.   Double IVC with a retroaortic left renal vein and azygos continuation in a 31-year-old woman. (a) Schematic shows the anomalous venous pattern. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) The right IVC receives the right renal vein (straight arrow). Note the left IVC (curved arrow). (c) The left IVC (arrow) receives the left renal vein. (d) The left renal vein (arrow) crosses posterior to the aorta to join the right IVC. (e) The right IVC continues cephalad as the azygos vein (arrow) within the retrocrural space.

View larger version (115K): [in a new window]   Figure 8e.   Double IVC with a retroaortic left renal vein and azygos continuation in a 31-year-old woman. (a) Schematic shows the anomalous venous pattern. (b-e) CT scans presented from caudal to cranial show the anomaly. (b) The right IVC receives the right renal vein (straight arrow). Note the left IVC (curved arrow). (c) The left IVC (arrow) receives the left renal vein. (d) The left renal vein (arrow) crosses posterior to the aorta to join the right IVC. (e) The right IVC continues cephalad as the azygos vein (arrow) within the retrocrural space.

View larger version (36K): [in a new window]   Figure 9a.   Hematuria and circumcaval ureter in a 65-year-old man. (a) Schematic shows the right ureter encircling the IVC. (b-d) CT scans presented from cranial to caudal show the anomaly. (b) The right ureter (arrow) is positioned posterior to the IVC. (c) The ureter (arrow) then courses to the left of the IVC. (d) Finally, the ureter (arrow) crosses anterior to the IVC. (Courtesy of Akira Kawashima, MD, Lyndon B. Johnson General Hospital, Houston, Tex.)

View larger version (87K): [in a new window]   Figure 9b.   Hematuria and circumcaval ureter in a 65-year-old man. (a) Schematic shows the right ureter encircling the IVC. (b-d) CT scans presented from cranial to caudal show the anomaly. (b) The right ureter (arrow) is positioned posterior to the IVC. (c) The ureter (arrow) then courses to the left of the IVC. (d) Finally, the ureter (arrow) crosses anterior to the IVC. (Courtesy of Akira Kawashima, MD, Lyndon B. Johnson General Hospital, Houston, Tex.)

View larger version (88K): [in a new window]   Figure 9c.   Hematuria and circumcaval ureter in a 65-year-old man. (a) Schematic shows the right ureter encircling the IVC. (b-d) CT scans presented from cranial to caudal show the anomaly. (b) The right ureter (arrow) is positioned posterior to the IVC. (c) The ureter (arrow) then courses to the left of the IVC. (d) Finally, the ureter (arrow) crosses anterior to the IVC. (Courtesy of Akira Kawashima, MD, Lyndon B. Johnson General Hospital, Houston, Tex.)

View larger version (90K): [in a new window]   Figure 9d.   Hematuria and circumcaval ureter in a 65-year-old man. (a) Schematic shows the right ureter encircling the IVC. (b-d) CT scans presented from cranial to caudal show the anomaly. (b) The right ureter (arrow) is positioned posterior to the IVC. (c) The ureter (arrow) then courses to the left of the IVC. (d) Finally, the ureter (arrow) crosses anterior to the IVC. (Courtesy of Akira Kawashima, MD, Lyndon B. Johnson General Hospital, Houston, Tex.)

View larger version (41K): [in a new window]   Figure 10a.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (104K): [in a new window]   Figure 10b.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (96K): [in a new window]   Figure 10c.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (116K): [in a new window]   Figure 10d.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (115K): [in a new window]   Figure 10e.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (160K): [in a new window]   Figure 10f.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)

View larger version (168K): [in a new window]   Figure 10g.   Hepatitis C and absent infrarenal IVC in a 48-year-old woman. (a) Schematic shows absence of the IVC below the renal veins. Collateral flow from the lower extremities reaches the azygos vein via paravertebral collateral veins. (b) CT scan obtained inferior to the aortic bifurcation shows absence of the common iliac veins. Enlarged ascending lumbar veins are present (black arrow). Note the iliac arteries (white arrow). (c) CT scan obtained inferior to the kidneys shows absence of the IVC (white arrow). Enlarged ascending lumbar veins are present (black arrow). (d) CT scan obtained at the level of the renal veins shows a normal prerenal IVC formed at the confluence of the renal veins (arrow). (e) CT scan obtained at the level of the prerenal IVC (white arrow) shows prominent paravertebral collateral veins (black arrow), which lead to a prominent azygos vein (arrowhead). (f) Coronal T1-weighted MR image shows the enlarged ascending lumbar veins (arrow). (g) Lateral maximum-intensity projection reconstruction of two-dimensional time-of-flight MR images shows formation of enlarged ascending lumbar veins at the confluence of the internal and external iliac veins (solid straight arrow). Note the anastomoses between the ascending lumbar veins and the azygos vein (open straight arrow) via prominent anterior paravertebral veins (white curved arrow). Also note the prerenal IVC (black arrowhead) posterior to the portal vein (black curved arrow), as well as prominent anterior abdominal wall collateral veins (white arrowheads). (Figs 10b, 10c, and 10g reprinted, with permission, from reference 19.)