Urol Radiol 14:188-190 (1992)
Urologic Radiology © Springer-VerlagNewYorkInc. 1992
Preaortic Iliac Venous Confluence ("Marsupial Cava"): A Rare Anomaly of the Inferior Vena Cava David M. Panicek, Paul V. O'Moore, and Ronald A. Castellino Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York and Cornell University Medical College, New York, New York, USA
Abstract. A patient was shown by computed tomography (CT) to have a rare developmental anomaly of the inferior vena cava (IVC), in which the iliac venous confluence is located anterior (rather than posterior) to the right common iliac artery. Recognition of the anomaly is important prior to surgical intervention in that area, as well as to prevent misinterpretation of the anomaly as representing adenopathy. Key words: Inferior vena cava -- Developmental anomalies -- CT.
Developmental anomalies of the inferior vena cava (IVC) and left renal vein are demonstrated not infrequently during cross-sectional imaging examinations [ 1-3]. Such anomalies include transposition of the IVC, duplication of the IVC, circumaortic left renal vein, and retroaortic left renal vein; azygos/ hemiazygos continuation of the IVC and circumcaval (retrocaval) ureter occur much less frequently. As a result of the complex series of embryological events that occur during development of the IVC, other anomalies of the IVC can and do occur rarely [4-7]. This report illustrates the computed tomographic (CT) appearance of the "preaortic iliac confluence" [7], a rare anomaly of the IVC in which the confluence of the common iliac veins is located an-
Address offprint requests to." David M. Panicek, M.D., Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
terior (rather than posterior) to the right common iliac artery or aortic bifurcation.
Case Report A 60-year-old woman with stage IIIc mesodermal mixed tumor of the left ovary underwent staging laparotomy, omentectomy, left salpingo-oophorectomy, fight oophorectomy, and tumor debulking. The patient never had surgery involving the aorta, IVC, or common iliac vessels. Subsequently, a CT scan was performed after administration of intravenous and oral contrast material to evaluate for response to postoperative chemotherapy. CT images of the lower abdomen (Fig. l) showed that the IVC and common iliac venous confluence were located anterior (rather than posterior) to the right c o m m o n iliac artery.
Discussion The final anatomic relationships of the IVC, its tributaries, the ureters, and the abdominal aorta are the result of a complex series of ascendencies and regressions of three paired embryological venous systems (posterior cardinal, supracardinal, and subcardinal) that occur during development [ l, 2, 4-7]. Several common developmental anomalies of the IVC are well known to those who interpret crosssectional imaging studies [1-3]. Awareness of the existence and imaging features of rarer anomalies of the IVC, however, is probably less universal. Recognition of such variations on imaging studies is important so that the surgeon can be alerted to its presence prior to procedures involving the abdominal vessels [3, 8]. For example, Brener et al. [8] state that venous hemorrhage is the most troublesome complication encountered during abdominal
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Fig. 1. Preaortic iliac venous confluence. Coned-down views of contrast-enhanced CT images of abdomen. A CT section near aortic bifurcation. Left lateral portion of IVC (V) is located anterior to distal aorta (A) at this level. B CT section 1 cm caudal to A. Right c o m m o n iliac artery (arrow) is coursing posterior to IVC (I1). C CT section 2 cm caudal to B, just cephalad to iliac venous confluence. Right common iliac artery (arrow) has coursed further to the right, posterior to the distal IVC (V). (Note incidental finding of prominent right ovarian vein entering IVC in A, and coursing lateral to opacified right ureter in B, C.)
aortic surgery, occurring particularly during dissection of the proximal infrarenal aorta and common iliac arteries. If aware before surgery that venous anomalies are present in those areas, the surgeon can plan appropriate approaches and maneuvers that lessen the risk ofintraoperative venous hemorrhage. Recognition of the CT features of IVC anomalies is also important to prevent misdiagnosis, since the CT appearance of a preaortic iliac venous confluence could be mistaken for adenopathy (Fig. 2) or other pericaval mass, particularly on noncontrast-enhanced scans. Evaluation of consecutive CT sections obtained with adequate vascular opacification should serve to elucidate whether such a mass represents a blood vessel. The case presented here, to our knowledge, is the first CT demonstration of a rare anomaly in which the IVC is located anterior, rather than posterior, to the right common iliac artery or aortic bifurcation. (Interestingly, such an anterior relationship of the IVC is typical for most marsupials,
in contradistinction to the posterior relationship present in placental animals [4, 5].) Normally, the common iliac venous confluence arises from a persistent anastomosis of the posterior cardinal veins located posterior to the developing aorta at 5 to 7 weeks of human development [1, 2, 4-7]. At the same time, a ventral pathway connects the somatic portion of the posterior cardinal veins with the future common iliac venous anastomosis. In 1929, Gladstone [6] reported the findings at postmortem anatomic dissection of a person with a retrocaval right common iliac artery. He reviewed the embryology and stated that "'Below the junction of the caudal mesonephric vein with the main posterior cardinal vein, a vein passes upward on each side from the interiliac anastomosis, in front of the umbilical artery, and joins the pelvic or somatic part of the postcardinal vein. This is the ventral limb of the circumumbilical venous ring, which on each side surrounds the future common iliac artery" [6]. He postulated that persistence of the ventral limb of the
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D.M. Panicek et al.: Preaortic Iliac Venous Confluence
Fig. 2. Precaval adenopathy in patient with metastatic testis cancer. Noncontrast-enhanced CT image demonstrates an enlarged precaval lymph node (arrow) that resembles preaortic iliac venous confluence (compare with Fig. 1C).
circumumbilical venous ring and regression of the dorsal limb accounted for the anomalous relationship of the IVC and right common iliac artery in the case he reported [6]. A subsequent review of vena caval anomalies by Edwards [7] cites the case of Gladstone [6] and mentions two other similar ones [5] in which the confluence of the common iliac veins was located anterior to the distal aorta. Edwards [7] proposed the term "preaortic confluence" for the anomalous vascular relationships present in those three cases, and concurred that the anomaly probably is due to persistence of the ventral limb of the circumumbilical ring, resulting in a marsupial-type cava [4, 5, 7]. Brener et al. [8] described a patient in whom the left limb of a duplicated IVC passed anterior to the aorta slightly cephalad to the aortic bifurcation, and suggested that the finding may represent preaortic iliac confluence or persistence of the left IVC. Those who interpret cross-sectional imaging examinations of the abdomen should be aware that rare anomalies of the IVC can occur, in addition to those anomalies that are more commonly encountered. Such anomalies should be specifically mentioned to the surgeon who may be performing procedures involving the abdominal vessels. Addendum: After this report was accepted for publication, we have encountered one additional "marsupial cava," seen on CT of a 56-year-old woman
with metastatic breast cancer. The CT appearance of the anomaly was virtually identical to that in the case presented above. Both of these cases were encountered by the same observer in a 10-month period, suggesting that the anomaly might not be extremely rare. References 1. Mayo J, Gray R, St. Louis E, Grosman H, McLoughlin M, Wise D: Anomalies of the inferior vena cava. A JR 140:339345, 1983 2. Kellman GM, Alpern MB, Sandier MA, Craig BM: Computed tomography of vena caval anomalies with embryologic correlation. RadioGraphics 8:533-556, 1988 3. Gomes MN, Choyke PL: Assessment of major venous anomalies by computerized tomography. J Cardiovasc Surg 31:621 628, 1990 4. McClure CFW, Butler EG: The development of the vena cava inferior in man. A m J A n a t 35:331-383, 1925 5. McClure CFW, Huntington GS: The mammalian vena cava posterior: An ontogenetic interpretation of the atypical forms of vena cava posterior (inferior) found in the adult domestic cat (Felis domestica) and in man. A m Anat Memoirs 15:1149, 1929 6. Gladstone RJ: Development of the inferior vena cava in the light of recent research, with especial reference to certain abnormalities, and current descriptions of the ascending lumbar and azygos veins. J A n a t 64:70-93, 1929 7. Edwards EA: Clinical anatomy of lesser variations of the inferior vena cava; and a proposal for classifying the anomalies of this vessel. Angiology 2:85-99, 1951 8. Brener BJ, Darling RC, Frederick PL, Linton RR: Major venous anomalies complicating abdominal aortic surgery. Arch Surg 108:159-165, 1974
Urologic Radiology © Springer-VerlagNewYorkInc. 1992
Preaortic Iliac Venous Confluence ("Marsupial Cava"): A Rare Anomaly of the Inferior Vena Cava David M. Panicek, Paul V. O'Moore, and Ronald A. Castellino Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York and Cornell University Medical College, New York, New York, USA
Abstract. A patient was shown by computed tomography (CT) to have a rare developmental anomaly of the inferior vena cava (IVC), in which the iliac venous confluence is located anterior (rather than posterior) to the right common iliac artery. Recognition of the anomaly is important prior to surgical intervention in that area, as well as to prevent misinterpretation of the anomaly as representing adenopathy. Key words: Inferior vena cava -- Developmental anomalies -- CT.
Developmental anomalies of the inferior vena cava (IVC) and left renal vein are demonstrated not infrequently during cross-sectional imaging examinations [ 1-3]. Such anomalies include transposition of the IVC, duplication of the IVC, circumaortic left renal vein, and retroaortic left renal vein; azygos/ hemiazygos continuation of the IVC and circumcaval (retrocaval) ureter occur much less frequently. As a result of the complex series of embryological events that occur during development of the IVC, other anomalies of the IVC can and do occur rarely [4-7]. This report illustrates the computed tomographic (CT) appearance of the "preaortic iliac confluence" [7], a rare anomaly of the IVC in which the confluence of the common iliac veins is located an-
Address offprint requests to." David M. Panicek, M.D., Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
terior (rather than posterior) to the right common iliac artery or aortic bifurcation.
Case Report A 60-year-old woman with stage IIIc mesodermal mixed tumor of the left ovary underwent staging laparotomy, omentectomy, left salpingo-oophorectomy, fight oophorectomy, and tumor debulking. The patient never had surgery involving the aorta, IVC, or common iliac vessels. Subsequently, a CT scan was performed after administration of intravenous and oral contrast material to evaluate for response to postoperative chemotherapy. CT images of the lower abdomen (Fig. l) showed that the IVC and common iliac venous confluence were located anterior (rather than posterior) to the right c o m m o n iliac artery.
Discussion The final anatomic relationships of the IVC, its tributaries, the ureters, and the abdominal aorta are the result of a complex series of ascendencies and regressions of three paired embryological venous systems (posterior cardinal, supracardinal, and subcardinal) that occur during development [ l, 2, 4-7]. Several common developmental anomalies of the IVC are well known to those who interpret crosssectional imaging studies [1-3]. Awareness of the existence and imaging features of rarer anomalies of the IVC, however, is probably less universal. Recognition of such variations on imaging studies is important so that the surgeon can be alerted to its presence prior to procedures involving the abdominal vessels [3, 8]. For example, Brener et al. [8] state that venous hemorrhage is the most troublesome complication encountered during abdominal
D.M. Panicek et al.: Preaortic Uiac Venous Confluence
189
Fig. 1. Preaortic iliac venous confluence. Coned-down views of contrast-enhanced CT images of abdomen. A CT section near aortic bifurcation. Left lateral portion of IVC (V) is located anterior to distal aorta (A) at this level. B CT section 1 cm caudal to A. Right c o m m o n iliac artery (arrow) is coursing posterior to IVC (I1). C CT section 2 cm caudal to B, just cephalad to iliac venous confluence. Right common iliac artery (arrow) has coursed further to the right, posterior to the distal IVC (V). (Note incidental finding of prominent right ovarian vein entering IVC in A, and coursing lateral to opacified right ureter in B, C.)
aortic surgery, occurring particularly during dissection of the proximal infrarenal aorta and common iliac arteries. If aware before surgery that venous anomalies are present in those areas, the surgeon can plan appropriate approaches and maneuvers that lessen the risk ofintraoperative venous hemorrhage. Recognition of the CT features of IVC anomalies is also important to prevent misdiagnosis, since the CT appearance of a preaortic iliac venous confluence could be mistaken for adenopathy (Fig. 2) or other pericaval mass, particularly on noncontrast-enhanced scans. Evaluation of consecutive CT sections obtained with adequate vascular opacification should serve to elucidate whether such a mass represents a blood vessel. The case presented here, to our knowledge, is the first CT demonstration of a rare anomaly in which the IVC is located anterior, rather than posterior, to the right common iliac artery or aortic bifurcation. (Interestingly, such an anterior relationship of the IVC is typical for most marsupials,
in contradistinction to the posterior relationship present in placental animals [4, 5].) Normally, the common iliac venous confluence arises from a persistent anastomosis of the posterior cardinal veins located posterior to the developing aorta at 5 to 7 weeks of human development [1, 2, 4-7]. At the same time, a ventral pathway connects the somatic portion of the posterior cardinal veins with the future common iliac venous anastomosis. In 1929, Gladstone [6] reported the findings at postmortem anatomic dissection of a person with a retrocaval right common iliac artery. He reviewed the embryology and stated that "'Below the junction of the caudal mesonephric vein with the main posterior cardinal vein, a vein passes upward on each side from the interiliac anastomosis, in front of the umbilical artery, and joins the pelvic or somatic part of the postcardinal vein. This is the ventral limb of the circumumbilical venous ring, which on each side surrounds the future common iliac artery" [6]. He postulated that persistence of the ventral limb of the
190
D.M. Panicek et al.: Preaortic Iliac Venous Confluence
Fig. 2. Precaval adenopathy in patient with metastatic testis cancer. Noncontrast-enhanced CT image demonstrates an enlarged precaval lymph node (arrow) that resembles preaortic iliac venous confluence (compare with Fig. 1C).
circumumbilical venous ring and regression of the dorsal limb accounted for the anomalous relationship of the IVC and right common iliac artery in the case he reported [6]. A subsequent review of vena caval anomalies by Edwards [7] cites the case of Gladstone [6] and mentions two other similar ones [5] in which the confluence of the common iliac veins was located anterior to the distal aorta. Edwards [7] proposed the term "preaortic confluence" for the anomalous vascular relationships present in those three cases, and concurred that the anomaly probably is due to persistence of the ventral limb of the circumumbilical ring, resulting in a marsupial-type cava [4, 5, 7]. Brener et al. [8] described a patient in whom the left limb of a duplicated IVC passed anterior to the aorta slightly cephalad to the aortic bifurcation, and suggested that the finding may represent preaortic iliac confluence or persistence of the left IVC. Those who interpret cross-sectional imaging examinations of the abdomen should be aware that rare anomalies of the IVC can occur, in addition to those anomalies that are more commonly encountered. Such anomalies should be specifically mentioned to the surgeon who may be performing procedures involving the abdominal vessels. Addendum: After this report was accepted for publication, we have encountered one additional "marsupial cava," seen on CT of a 56-year-old woman
with metastatic breast cancer. The CT appearance of the anomaly was virtually identical to that in the case presented above. Both of these cases were encountered by the same observer in a 10-month period, suggesting that the anomaly might not be extremely rare. References 1. Mayo J, Gray R, St. Louis E, Grosman H, McLoughlin M, Wise D: Anomalies of the inferior vena cava. A JR 140:339345, 1983 2. Kellman GM, Alpern MB, Sandier MA, Craig BM: Computed tomography of vena caval anomalies with embryologic correlation. RadioGraphics 8:533-556, 1988 3. Gomes MN, Choyke PL: Assessment of major venous anomalies by computerized tomography. J Cardiovasc Surg 31:621 628, 1990 4. McClure CFW, Butler EG: The development of the vena cava inferior in man. A m J A n a t 35:331-383, 1925 5. McClure CFW, Huntington GS: The mammalian vena cava posterior: An ontogenetic interpretation of the atypical forms of vena cava posterior (inferior) found in the adult domestic cat (Felis domestica) and in man. A m Anat Memoirs 15:1149, 1929 6. Gladstone RJ: Development of the inferior vena cava in the light of recent research, with especial reference to certain abnormalities, and current descriptions of the ascending lumbar and azygos veins. J A n a t 64:70-93, 1929 7. Edwards EA: Clinical anatomy of lesser variations of the inferior vena cava; and a proposal for classifying the anomalies of this vessel. Angiology 2:85-99, 1951 8. Brener BJ, Darling RC, Frederick PL, Linton RR: Major venous anomalies complicating abdominal aortic surgery. Arch Surg 108:159-165, 1974
