J Clin Ultrasound 20:481-485, September 1992 0 1992 by John Wiley & Sons, Inc. CCC 0092-2751/92/070481-05 $04.00
Case Report
Ipsilateral Duplication of the Inferior Vena Cava Anthony J. Doyle, MB ChB, FRACR, Michael G. Melendez, MD, and Margaret A. Simons, MD
Dup ication of the inferior vena cava (IVC) is an uncommon but well-recognized phenomenon, with an incidence estimated between 0.3%l and 2.8%.' The descriptions of this entity always re-
~~
From the Department of Radiology, School of Medicine, University of Utah, Salt Lake City, Utah. For reprints contact Anthony J. Doyle, MD, Department of Radiology, School of Medicine, 50 North Medical Drive, University of Utah, Salt Lake City, Utah 84132.
fer to bilateral venae cavae lying on opposite sides of the aorta. To our knowledge, no case of paired IVCs lying on the same side of the aorta has previously been described. We present such a case in which this rare entity initially caused confusion on an abdominal computed tomography (CT) scan. We present it so that radiologists may be aware of this rare anomaly and to show its appearance on ultrasound examination, with magnetic resonance angiography (MRA) correlation.
FIGURE 1. An axial CT scan below the level of the renal vessels shows two round structures (arrows) to the right of the aorta, initially interpreted as representing the IVC with retro caval adenopathy.
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CASE REPORT: DOYLE ET AL.
FIGURE 2. (A) Sagittal real-time ultrasonography shows parallel tubular structures (arrows) joining at the level of the renal veins. (B) An axial color Doppler image shows venous flow in both tubular structures (arrows). JOURNAL OF CLINICAL ULTRASOUND
IPSILATERAL DUPLICATION OF THE IVC
483
FIGURE 3. (A) An axial SPGR image at a similar level to Figure 1 and 2 shows flow related enhancement in the two right venous channels and the adjacent aorta (AO). (B) An MRA reconstruction of the sequence used in (a) and viewed from the left shows the two venous channels (*)joining at the level of the renal veins to form the suprarenal inferior vena cava (ivc) (ANT = anterior, SUP = superior).
VOL. 20. NO.7 , SEPTEMBER 1992
CASE REPORT: DOYLE ET AL.
484
CASE REPORT
A 57-year-old man presented to an outside hospital for an abdominal CT. Clinically, there was a suspicion of lymphoma. The scan was performed without intravenous contrast since the patient had renal failure. The abdominal CT was interpreted as showing retrocaval adenopathy on the right (Figure 1). The patient was then referred to the University of Utah for further assessment. Review of the outside CT showed that the structures interpreted as enlarged nodes followed a tubular course posterior to the IVC. The suspicion of a vascular channel was raised. Imagedirected and color Doppler ultrasonography were performed using a Quantum 2000 scanner (Quantum Medical Systems, Issaquah, Washington). This revealed a double venous channel to the right of the aorta with venous signals within both channels (Figure 2). This double channel persisted caudally to join with the iliac veins. We also performed short flip-angle magnetic resonance scanning using spoiled GRASS (SPGR) two-dimensional time of flight angiography sequences on a General Electric Signa scanner (General Electric, Milwaukee, Wisconsin), which demonstrated the double venous channels joining at the level of the renal veins (Figure 3). These studies conclusively demonstrated that the retroperitoneal structures seen on the original CT were venous channels and not lymph nodes. The arrangement of the venous channels is very interesting. The anomaly is confined to the infrarenal vena cava. The left renal vein passes anterior to the aorta in the normal fashion with no venous pathways seen posterior to the aorta. Distally, we showed the more anterior of the venae cavae to cross to the left anterior t o the aorta and connect to the left iliac vein. The more posterior channel stays to the right of the aorta and becomes the right iliac vein lying lateral to the right iliac artery. We did not demonstrate any communication between the two venae cavae below the level of the renal veins, although small communications could exist and not be visible in these studies. DISCUSSION
The embryology of the IVC is complex and controversial, but the basic pattern outlined by Huntington and McClure in 19203 is still adhered to. This maintains that the normal IVC is derived from the right supracardinal vein after the infrarenal subcardinal and postcardinal
veins have regressed. The relatively common retrocaval ureter normally is said to be derived from persistence of the right postcardinal vein. The less common left-sided IVC derives from persistence of the left supracardinal vein with regression of the right, and the duplicated IVC allegedly arises from persistence of both left and right supracardinal veins. Previous descriptions of the duplicated IVC have referred to venous channels on opposite sides of the aorta. The communication between these is usually at the level of the renal veins,4 although aberrant communications more distally have been described, including one at the level of the iliac veins.4 To our knowledge, an ipsilateral duplicated IVC has not been described. The embryology of this is an interesting puzzle. As far as we could tell from our noncontrast studies, the ureter in this case lies lateral to both venous channels throughout their length. This effectively excludes persistence of the right postcardinal vein as accounting for either of the channels since the ureter would normally pass posterior to the postcardinal vein at the level of the kidney, heading toward the midline, then pass anteriorly on the medial side of the postcardinal vein before heading inferolaterally on the anterior aspect of the postcardinal vein. The ureter does not appear to describe such a loop around either of the venous channels in this case. Consequently, they must be derived from supracardinal or subcardinal veins. It seems unlikely that the left supracardinal vein would be displaced to the right of the aorta over such a long course and the junction of the two channels to the right of the aorta would be unusual in that case also. It seems more likely that the double channel is somehow derived from the right supracardinal and subcardinal veins, with the communication to the left iliac being a vestige of anastomoses between the right subcardinal vein and the left subcardinal andlor common postcardinal systems. This anomaly, although extremely uncommon, should be recognized by radiologists. Demonstration of the venous channels by Doppler ultrasonography or MRA is straightforward and shows the anatomy exquisitely, thus removing any doubt about the diagnosis. ACKNOWLEDGMENTS
Financial assistance from Quantum Medical Systems for the illustrations in this article is gratefully appreciated. JOURNAL OF CLINICAL ULTRASOUND
IPSILATEFUL DUPLICATION OF THE IVC
REFERENCES 1. Mayo J, Gray R, St. Louis E, Grosman H, McLoughlin M, Wise D: Anomalies of the inferior vena cava. AJR 140:339-345,1983. 2. Sieb GA: The azygos system of veins in American whites and American negroes, including observations on the inferior caval venous system. A m J Phys Anthropol 19:39- 163, 1934. 3. Huntington GS, McClure CFW: The development of the veins in the domestic cat (Felis Domestica) with
VOL. 20, NO. 7, SEPTEMBER 1992
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especial reference, 1)to the share taken by the supra cardinal veins in the development of the post cava and azygous veins and 2) to the interpretation of the variant conditions of the post cava and its tributaries, as found in the adult. Anat Rec 20:l30, 1920. 4. Chuang vp, Mena CE, Hoskins PA: Congenital anomalies of the inferior vena cava. Review of embryogenesis and presentation of a simplified classification. Br J Radio1 47:206-213, 1974.
Case Report
Ipsilateral Duplication of the Inferior Vena Cava Anthony J. Doyle, MB ChB, FRACR, Michael G. Melendez, MD, and Margaret A. Simons, MD
Dup ication of the inferior vena cava (IVC) is an uncommon but well-recognized phenomenon, with an incidence estimated between 0.3%l and 2.8%.' The descriptions of this entity always re-
~~
From the Department of Radiology, School of Medicine, University of Utah, Salt Lake City, Utah. For reprints contact Anthony J. Doyle, MD, Department of Radiology, School of Medicine, 50 North Medical Drive, University of Utah, Salt Lake City, Utah 84132.
fer to bilateral venae cavae lying on opposite sides of the aorta. To our knowledge, no case of paired IVCs lying on the same side of the aorta has previously been described. We present such a case in which this rare entity initially caused confusion on an abdominal computed tomography (CT) scan. We present it so that radiologists may be aware of this rare anomaly and to show its appearance on ultrasound examination, with magnetic resonance angiography (MRA) correlation.
FIGURE 1. An axial CT scan below the level of the renal vessels shows two round structures (arrows) to the right of the aorta, initially interpreted as representing the IVC with retro caval adenopathy.
481
482
CASE REPORT: DOYLE ET AL.
FIGURE 2. (A) Sagittal real-time ultrasonography shows parallel tubular structures (arrows) joining at the level of the renal veins. (B) An axial color Doppler image shows venous flow in both tubular structures (arrows). JOURNAL OF CLINICAL ULTRASOUND
IPSILATERAL DUPLICATION OF THE IVC
483
FIGURE 3. (A) An axial SPGR image at a similar level to Figure 1 and 2 shows flow related enhancement in the two right venous channels and the adjacent aorta (AO). (B) An MRA reconstruction of the sequence used in (a) and viewed from the left shows the two venous channels (*)joining at the level of the renal veins to form the suprarenal inferior vena cava (ivc) (ANT = anterior, SUP = superior).
VOL. 20. NO.7 , SEPTEMBER 1992
CASE REPORT: DOYLE ET AL.
484
CASE REPORT
A 57-year-old man presented to an outside hospital for an abdominal CT. Clinically, there was a suspicion of lymphoma. The scan was performed without intravenous contrast since the patient had renal failure. The abdominal CT was interpreted as showing retrocaval adenopathy on the right (Figure 1). The patient was then referred to the University of Utah for further assessment. Review of the outside CT showed that the structures interpreted as enlarged nodes followed a tubular course posterior to the IVC. The suspicion of a vascular channel was raised. Imagedirected and color Doppler ultrasonography were performed using a Quantum 2000 scanner (Quantum Medical Systems, Issaquah, Washington). This revealed a double venous channel to the right of the aorta with venous signals within both channels (Figure 2). This double channel persisted caudally to join with the iliac veins. We also performed short flip-angle magnetic resonance scanning using spoiled GRASS (SPGR) two-dimensional time of flight angiography sequences on a General Electric Signa scanner (General Electric, Milwaukee, Wisconsin), which demonstrated the double venous channels joining at the level of the renal veins (Figure 3). These studies conclusively demonstrated that the retroperitoneal structures seen on the original CT were venous channels and not lymph nodes. The arrangement of the venous channels is very interesting. The anomaly is confined to the infrarenal vena cava. The left renal vein passes anterior to the aorta in the normal fashion with no venous pathways seen posterior to the aorta. Distally, we showed the more anterior of the venae cavae to cross to the left anterior t o the aorta and connect to the left iliac vein. The more posterior channel stays to the right of the aorta and becomes the right iliac vein lying lateral to the right iliac artery. We did not demonstrate any communication between the two venae cavae below the level of the renal veins, although small communications could exist and not be visible in these studies. DISCUSSION
The embryology of the IVC is complex and controversial, but the basic pattern outlined by Huntington and McClure in 19203 is still adhered to. This maintains that the normal IVC is derived from the right supracardinal vein after the infrarenal subcardinal and postcardinal
veins have regressed. The relatively common retrocaval ureter normally is said to be derived from persistence of the right postcardinal vein. The less common left-sided IVC derives from persistence of the left supracardinal vein with regression of the right, and the duplicated IVC allegedly arises from persistence of both left and right supracardinal veins. Previous descriptions of the duplicated IVC have referred to venous channels on opposite sides of the aorta. The communication between these is usually at the level of the renal veins,4 although aberrant communications more distally have been described, including one at the level of the iliac veins.4 To our knowledge, an ipsilateral duplicated IVC has not been described. The embryology of this is an interesting puzzle. As far as we could tell from our noncontrast studies, the ureter in this case lies lateral to both venous channels throughout their length. This effectively excludes persistence of the right postcardinal vein as accounting for either of the channels since the ureter would normally pass posterior to the postcardinal vein at the level of the kidney, heading toward the midline, then pass anteriorly on the medial side of the postcardinal vein before heading inferolaterally on the anterior aspect of the postcardinal vein. The ureter does not appear to describe such a loop around either of the venous channels in this case. Consequently, they must be derived from supracardinal or subcardinal veins. It seems unlikely that the left supracardinal vein would be displaced to the right of the aorta over such a long course and the junction of the two channels to the right of the aorta would be unusual in that case also. It seems more likely that the double channel is somehow derived from the right supracardinal and subcardinal veins, with the communication to the left iliac being a vestige of anastomoses between the right subcardinal vein and the left subcardinal andlor common postcardinal systems. This anomaly, although extremely uncommon, should be recognized by radiologists. Demonstration of the venous channels by Doppler ultrasonography or MRA is straightforward and shows the anatomy exquisitely, thus removing any doubt about the diagnosis. ACKNOWLEDGMENTS
Financial assistance from Quantum Medical Systems for the illustrations in this article is gratefully appreciated. JOURNAL OF CLINICAL ULTRASOUND
IPSILATEFUL DUPLICATION OF THE IVC
REFERENCES 1. Mayo J, Gray R, St. Louis E, Grosman H, McLoughlin M, Wise D: Anomalies of the inferior vena cava. AJR 140:339-345,1983. 2. Sieb GA: The azygos system of veins in American whites and American negroes, including observations on the inferior caval venous system. A m J Phys Anthropol 19:39- 163, 1934. 3. Huntington GS, McClure CFW: The development of the veins in the domestic cat (Felis Domestica) with
VOL. 20, NO. 7, SEPTEMBER 1992
485
especial reference, 1)to the share taken by the supra cardinal veins in the development of the post cava and azygous veins and 2) to the interpretation of the variant conditions of the post cava and its tributaries, as found in the adult. Anat Rec 20:l30, 1920. 4. Chuang vp, Mena CE, Hoskins PA: Congenital anomalies of the inferior vena cava. Review of embryogenesis and presentation of a simplified classification. Br J Radio1 47:206-213, 1974.
