Interruption or congenital stenosis of the inferior vena cava: Prevalence, imaging, and clinical findings

European Journal of Radiology 62 (2007) 257–266

Interruption or congenital stenosis of the inferior vena cava: Prevalence, imaging, and clinical findings Zafer Koc ∗ , Levent Oguzkurt Ba¸skent University, School of Medicine, Department of Radiology, Adana, Turkey Received 4 September 2006; received in revised form 13 November 2006; accepted 16 November 2006

Abstract Objective: To present the prevalence, clinical, and imaging findings of interruption or congenital stenotic lesions of the inferior vena cava (IVC), associated malformations, and their clinical relevance. Materials and methods: Between March 2004 and March 2006, 7972 patients who had undergone consecutive routine abdominal multidetector row computed tomography were analyzed for interruption or stenotic lesion of the IVC. Results: Prevalence of interruption (n = 8) or congenital stenosis (n = 4) of the IVC occurred in 12 (0.15%) of 7972 patients. Four patients with interruption and four patients with congenital stenosis of the IVC were symptomatic with DVT (n = 4), leg swelling (n = 4), leg pain (n = 2), lower extremity varices (n = 2), hepatic vein thrombosis (n = 1), and hematochezia (n = 1). All four of the asymptomatic patients were from the interruption group, and these patients had interrupted IVC with well-developed azygos/hemiazygos continuation. Eight symptomatic patients did not have a well-developed azygos/hemiazygos continuation, and drainage of lower extremity was mainly from collateral veins. Additional findings in eight symptomatic patients were abdominal venous collaterals (n = 8), venous aneurysm (n = 2), lower extremity varices (n = 2), varicocele (n = 2), and pelvic varices (n = 1). Conclusion: Interruption or stenosis of the IVC are rare on routine abdominal CT examinations and may cause different clinical findings depending on the variant drainage patterns or collaterals. Interrupted IVC is commonly asymptomatic if associated with well-developed azygos/hemiazygos continuation, whereas commonly symptomatic if well-developed azygos/hemiazygos continuation is not present. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Congenital; Interrupted; Stenosis; Inferior vena cava; Variants; Computed tomography; Magnetic resonance imaging

1. Introduction Congenital anomalies and variations of the inferior vena cava (IVC) are uncommon. In general, knowledge of existence of IVC anomalies has been important for better planning of operative procedures such as aortic and renal surgery [1]. They can lead to life-threatening complications if not identified before or during abdominal surgery or interventional procedures. Interruption or congenital stenotic lesions of the IVC are rare vascular defects and result from aberrant development of the IVC segments (Fig. 1) during embryogenesis [2,3]. Interrupted IVC is characterized by a developmental defect of the IVC and col∗

Corresponding author at: Bas¸kent Universitesi Adana Hastanesi, Dadalo˘glu Mah. Serin Evler 39. Sok. No: 6 Y¨ure˘gir, 01250 Adana, Turkey. Tel.: +90 322 3272727 1025; fax: +90 322 3271270. E-mail addresses: [email protected], [email protected] (Z. Koc). 0720-048X/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2006.11.028

lateral circulation most commonly via the azygos-hemiazygos system. The reported prevalence rate of interrupted IVC with azygos or hemiazygos continuation is 0.6% [3–5]. Congenital stenosis of the IVC is characterized by narrowing with or without a web formation mostly at the diaphragmatic level or hepatic segment of the IVC [3,6]. Noninvasive imaging modalities such as multidetector row computed tomography (MDCT) and magnetic resonance imaging (MRI) are the most reliable methods for identification of these anomalies [5,7]. Interrupted IVC was defined previously as a rare but commonly asymptomatic variant [3,5]. Recent studies have revealed that some patients with interrupted IVC or congenital stenotic lesions of IVC commonly presented with recurrent DVT and thrombo-embolic attacks relatively young persons [8]. Our experience has been similar. In this report, we present imaging findings and clinical importance of the anomalies in the 12 patients with interrupted IVC or stenotic lesions of the IVC and associated malformations.

258

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

Fig. 1. Diagram of inferior vena cava in coronal plane illustrates the final structure of the inferior vena cava and its embryologic origin. Number 1 indicates iliac segment arises from the posterior cardinal veins; 2, subrenal segment arises from the right supracardinal vein; 3, renal segment arises from the anastomosis between the right supracardinal and subcardinal veins; 4, suprarenal segment arises from the right subcardinal vein; and 5, hepatic segment arises from the hepatocardiac canal.

2. Materials and methods The institutional review board of the university approved this study. Written informed consent was obtained from each subject. Between March 2004 and March 2006, the CT scans of 7972 patients at our hospital (aged ≥ 14 years) who had undergone consecutive routine abdominal contrast-enhanced MDCT were examined. The data was collected prospectively. There were 12 patients (0.15%) out of 7972 with interrupted or stenotic lesion of the IVC who formed the basis of this study. Patients were four women (33%) and eight men (67%) aged 14–56 years (mean age ± S.D.: 34.5 ± 13.35 years). The reasons for CT examination were to define the etiology and extension of DVT (n = 4), to define the extent of intra-abdominal tumor (n = 3), to demonstrate a hypoplastic kidney (n = 1), and to search for epigastric pain (n = 1). The other three patients underwent CT to inves-

tigate central vein stenosis because of abdominal and/or lower extremity varices and planning of endovascular treatment. All the CT scans were obtained using a four-channel MDCT scanner (Sensation 4; Siemens, Erlangen, Germany). The portal phase images used to assess abdominal venous structures were acquired 60 s after a 120–150 mL intravenous bolus of nonionic contrast material (iohexol, 300 mg/mL; OmnipaqueTM , Amersham, Cork, Ireland) was administered at 3–5 mL/s. The scanning parameters were contiguous 2.5-mm collimation, 12.5mm/0.5-s table speed per 360◦ gantry rotation with a resultant pitch value of 1.25, at 120 kVp, 120–155 mA. Ten of the 12 patients also underwent preliminary pelvic CT without contrast injection. All scans were analyzed at a workstation (Volume Wizard; Siemens Medical Systems). Postprocessing techniques (maximum intensity projection, multiplanar reconstruction or volume rendering) were used in most but not all the cases. The images were independently evaluated by two experienced radiologists. If the interpretations differed, a consensus was reached by subsequent meeting. We used a standardized form for a specific search of venous variations and anomalies in each patient. All the abdominal venous variations including interrupted IVC and stenotic lesions of the IVC had been recorded. All the associated venous variations or venous abnormality, azygos/hemiazygos continuation and other collateral pathways including retroperitoneal, intraabdominal or abdominal wall had been recorded. In all 12 patients, clinical complaint if it existed, CT findings, treatment if needed, and treatment outcomes were recorded. These additional data were obtained by detailed history and physical examination at the time of presentation. For differential diagnosis of the congenital and acquired origin of the IVC stenosis; the clinical presentation, age and spontaneous or secondary onset of symptoms, previous thrombotic episodes, IVC lesion characteristics, and other findings obtained by CT or interventional procedures were evaluated by two radiologists. Presence of diffuse rich venous collaterals, an atretic/hypoplastic segment or web in the IVC, presenting with relatively younger age accepted as signs of the congenital origin [9,10]. And if there is a tumor invasion, trauma or surgery related with IVC stenosis; these findings accepted as a sign of the acquired origin [11] and these patients excluded. In addition to contrast-enhanced abdominal MDCT in every patient, two patients had magnetic resonance imaging or MR venography with 1.5 T MR imager (Avanto, Siemens, Erlangen, Germany), six patients had color Doppler ultrasound examination with ultrasound scanner by using 7.5-MHz linear and 2–4-MHz convex-array transducer (Sonoline Antares, Siemens, Erlangen, Germany), and five patients had venography with digital subtraction angiography (Multistar, Siemens, Erlangen, Germany). These last five patients had endovascular interventional procedures following venography. Venous intervention was planned for one patient with interrupted IVC and diffuse abdominal collaterals, but the patient refused treatment. Coagulation studies for thrombophilia, including activated protein-C resistance, antithrombin level, protein C and S levels, antiphospholipid antibodies, homocysteine serum concentration, factor-V Leiden mutation were performed in all patients

Table 1 Imaging and clinical findings of 12 patients with interruption or congenital stenosis of the IVC No.

Age/sex Imaging findings (CT/MRI/Venography/CDUS)

Clinical findings

Treatment

Associated abnormality, collaterals

Additional findings

Thrombophilia test

Presenting complaints

Acute DVT of the IVC-iliac and bilateral femoro-popliteal deep veins HV thrombosis (obstructive hepatocavopathy), bilateral varicocele, abdominal and bilateral lower extremity varices Acute superimposed chronic recurrent DVT of the IVC-bilateral iliac and femoro-popliteal deep veins Hemorrhoids and bilateral varicocele

Factor-V Leiden mutation

Bilateral lower extremity swellings and pain

Thrombolysis and IVC stenting

–

Abdominal pain, bilateral lower extremity and abdominal varices

Balloon angioplasty

Normal

Bilateral lower extremity swellings and pain, venous ulcerations

Thrombolysis

–

Hematochezia

Venous intervention planned

Protein S and antithrombin deficiency

Right lower extremity swellings and pain

Thrombolysis and IVC stenting

–

Asymptomatic

–

–

–

Asymptomatic

–

Azygos continuation

–

–

Asymptomatic

–

Total situs inversus, azygos continuation, right renal hypoplasia HV stenosis, intrahepatic (HV) collaterals, caudate HV aneurysm Intra-abdominal and superficial abdominal collaterals drain to IVC Infrarenal interruption and total hypoplasia of IVC; para-intraspinal and superficial abdominal collaterals

Inverted persistent left SVC

–

Asymptomatic

–

HV thrombosis (obstructive hepatocavopathy)

Normal

R upper abdominal pain

Intervention planned (Balloon angioplasty)

Bilateral lower extremity varices.

–

Bilateral lower extremity varices

Follow-up

Chronic recurrent DVT and venous insufficiency, crural, femoral, iliac vein, and IVC occlusion

Normal

Bilateral lower extremity swellings

Thrombectomy-my and stenting

1

30/M

Suprarenal interrupted IVC

Diffuse paravertebral and retroperitoneal collaterals

2

24/M

Suprahepatic IVC stenosis with web

Intrahepatic (HV), paraspinal, intraspinal, and superficial abdominal wall collaterals, paravertebral vein aneurysm,

3

30/M

Infrarenal IVC stenosis

Intra-abdominal collateral veins

4

48/M

Infrarenal interrupted IVC

5

14/F

Infrarenal interrupted IVC

Diffuse retroperitoneal, intra-abdominal IVC-renal, and portal collateral veins Diffuse paravertebral, intraspinal, and gonadal collaterals drains to renal vein

6

34/M

Interrupted left IVC suprarenal level

7

24/F

8

35/F

9

53/F

Interrupted left IVC suprarenal level Interrupted IVC suprarenal level Interrupted IVC suprarenal level

10

56/F

Suprahepatic IVC stenosis

11

45/F

Suprahepatic IVC stenosis with web

12

21/M

Suprarenal interrupted and hypoplastic hepatic IVC

Heterotaxia syndrome; double and interrupted IVC, azygos continuation Hemiazygos continuation

Acute DVT of the IVC-right iliac and femoro-popliteal and superficial veins, pelvic varices Congenital portal-caval shunt, polysplenia

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

IVC Lesion and location

IVC: inferior vena cava, SVC: superior vena cava, MRI: magnetic resonance imaging, CT: computed tomography, CDUS: color Doppler ultrasound, M: male, F: female, L: left, LAB: laboratory tests. 259

260

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

Fig. 2. 30-year-old man, had suprarenal interrupted inferior vena cava (IVC), presenting with bilateral lower extremity deep vein thrombosis (DVT), leg swelling, and pain. (A) Coronal curved planar thin-slab maximum intensity projection (MIP) CT image showing atretic suprarenal segment of the IVC (open arrow), deep vein thrombosis of the distal IVC and bilateral iliac veins (*), bilateral paravertebral, retroperitoneal and gonadal collateral veins (arrowheads), and distended gonadal veins (white arrows). (B) After treatment of DVT digital subtracted venography also showed atretic segment of the IVC (arrows).

with lower extremity DVT. Thrombosis was acute (≤14 days) in two patients, acute superimposed on chronic in 1, and chronic (>14 days) in 1. All four patients with DVT had one or more short- or long-term complaint of leg swelling, pain on walking, and/or varicose veins. All four patients with DVT underwent catheter-directed endovascular treatment. 3. Results Interruption or stenosis of the IVC was identified in 12 (0.15%) of the 7972 patients who had undergone routine abdominal contrast-enhanced MDCT. Imaging and clinical findings of 12 patients with interruption (n = 8) or congenital stenosis (n = 4) of the IVC are summarized in Table 1. Eight of the 12 patients were symptomatic with leg swelling (n = 4), leg pain (n = 2), lower extremity varices (n = 2), abdominal pain (n = 2), and hematochezia (n = 1). Deep vein thrombosis was diagnosed in four patients and hepatic vein thrombosis in one patient. Additional findings in eight symptomatic patients were abdominal venous collaterals (n = 8), venous aneurysm (n = 2), lower extremity varices (n = 2), varicocele (n = 2), and pelvic varices (n = 1). The other four patients were asymptomatic and interruption of IVC was incidentally identified in these patients. Of eight patients with interrupted IVC, four were (50%) asymptomatic and four (50%) were symptomatic because of lower extremity DVT in three of them (Fig. 2), and diffuse abdominal collaterals including hemorrhoidal caval-portal presenting with hematochezia in one of them. These four patients with symptomatic IVC interruption had suprarenal (n = 2) or subrenal (n = 2) interrupted IVC. The patients with subrenal

interruption of the IVC had diffuse abdominal collaterals including paravertebral, intraspinal and gonadal venous collaterals and intraabdominal varicose veins. One of them had varicocele and hemorrhoids, other patient had pelvic varices (Fig. 3). All four asymptomatic patients had IVC interruption at the suprarenal level and associated with well-developed azygos (n = 2) or hemiazygos (n = 2) continuation. One of these patients had heterotaxy syndrome (Fig. 4). Four patients had stenosis of the IVC and all (100%) of them were symptomatic. Two of them had a web in the suprahepatic IVC demonstrated by MDCT (Fig. 5) and two other patients had intrinsic stenosis of the IVC without web formation (Fig. 6). One of these patients with IVC stenosis had hepatic vein thrombosis, two of them had intrahepatic, and three of them had extrahepatic abdominal venous collaterals, lower extremity varices (n = 2), varicocele (n = 1), and venous aneurysm (n = 2). In symptomatic group, abdominal wall collateral veins visible on the skin surface were identified in three of the eight patients. Increased venous pressure was identified during intervention in three of the five patients intervention performed. The drainage of blood from the lower half of the body to the proximal side of the interrupted/stenotic segment or right heart coursed through the diffuse intra-abdominal collaterals and azygos-hemiazygos vein (n = 5), intra-abdominal and abdominal wall collaterals (n = 3), and azygos-hemiazygos system only (n = 4). Four of the patients with interruption or congenital stenosis of the IVC presented with DVT and the ages of these patients ranged between 14 and 30 (mean ± S.D.: 23.8 ± 7.8) years. The coagulation studies revealed a thrombophilic defect predisposing to thrombosis in two of the four patients with DVT. One

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

261

Fig. 3. 14-year-old woman, had subrenal interrupted inferior vena cava (IVC), presenting with IVC and right lower extremity deep vein thrombosis (DVT), leg swelling and pain. (A and B) Coronal curved planar thin-slab maximum intensity projection CT images showing atretic segment of the IVC (arrow, A), bilateral paravertebral-retroperitoneal (small arrows) and gonadal (large arrows) collateral veins, and pelvic varices (arrowheads, B). After treatment of DVT digital subtracted venography obtained in lateral projection (C) shows diffuse paraspinal (arrows) and intraspinal-epidural (arrowheads) collateral veins draining into the renal-suprarenal segments of the IVC (large arrow) (U: Uterus).

262

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

Fig. 4. 34-year-old man presenting with nonspecific abdominal pain, had total situs inversus and polysplenia (heterotaxia syndrome and left isomerism). Curved planar thin MIP image shows the interrupted left inferior vena cava (arrows) and azygos continuation (arrowheads). Some distorsion can be seen because of a curved planar reconstruction of the image for tracing the azygos vein. Hepatic veins drains into right atrium via suprahepatic inferior vena cava (small arrows).

patient had protein S and antithrombin deficiency and one patient had factor-V Leiden mutation. Laboratory tests for thrombophilia were only performed in patients with lower extremity DVT. All patients with acute or chronic lower extremity DVT had percutaneous endovascular treatment by interventional radiology. 4. Discussion This study revealed that prevalence of interruption or congenital stenosis of the IVC was 0.15% (12 in 7972) patients. It also was shown that interrupted or stenotic lesion of the IVC were mostly symptomatic with leg swelling (33%), leg pain (17%), varices of lower extremities (17%), abdominal pain (17%), and rarely hematochezia (8%). The most common cause of presenting symptoms was DVT, and these patients typically were of a relatively young age (range, 14–30 years). Well-developed azygos/hemiazygos continuation was observed in all patients who were asymptomatic. Our study suggests that 50% of the cases of the interruption were symptomatic, and 100% of the cases of the stenosis were symptomatic. There was an important difference in the collateral circulation between the asymptomatic and symptomatic group. Our experience with this group of patients showed us that if interrupted IVC was associated with well-developed azygos or hemiazygos continuation, as was the case in four out of eight patients, the variant was identified incidentally and patients were asymptomatic. If well-developed azygos/hemiazygos continuation was not present, or drainage was from other collaterals, these patients presented with symptoms such as lower extremity DVT or varicose veins. Embryologic development of the IVC is a complex process that includes formation, regression, and fusion of the three longitudinal pairs of veins: postcardinal, subcardinal, and

supracardinal [1,5]. These processes occur between the fifth and seventh weeks of gestation, and five embryologic segments form the final structure of the IVC (Fig. 1) [3,5,12]. In caudal-cranial order, these segments are: posterior cardinal veins (iliac segment); right supracardinal vein (subrenal segment); anastomosis between the right supra- and subcardinal veins (renal segment); right subcardinal vein (suprarenal segment); and hepatocardiac canal (hepatic segment) [3,12]. During this complex transformation of the IVC, numerous variations and anomalies to its adult form may occur [5]. Anastomosis between the paired veins are explains the potential for each of the different routes of collateral flow. Interruption of the IVC most likely results from agenesis of a segment of the IVC [3], or a fusion defect between the suprarenal and hepatic segment of the IVC [1,5,12]. Short segmental atresia of the subrenal IVC possibly stems from a fusion defect between the subrenal and renal segments. But absence of the subrenal segment of the IVC is commonly accepted as the result of a thrombosis of the subrenal IVC in prenatal or perinatal period [3,5,13–15]. Thrombophilia defect were identified in our two cases, one of them had subrenal and other had suprarenal defect of the IVC. These findings imply that prenatal or perinatal thrombosis of the IVC may be related the interruption of the IVC. Congenital membranous obstruction of the IVC (Fig. 5) is most likely stems from a fusion defect between the suprarenal and hepatic segment of the IVC [3]. Patients with interruption or congenital stenosis of the IVC may be present with different clinical symptoms such as leg swelling and leg pain with or without lower extremity DVT [16], bilateral lower extremity varices, bilateral varicocele, rarely abdominal pain due to hepatic vein thrombosis, radiculopathy due to intraspinal collaterals [17], or hematochezia due to venous congestion secondary to perirectal caval-portal collaterals [18]. Interruption of the IVC also has been considered as a contributory factor in the development of lower extremity DVT in patients with thrombophilic defects predisposing to thrombosis. MDCT and venography are a diagnostic standard of the variants and anomalies of the IVC. Interruption or stenotic lesion of the IVC can be diagnosed as absent or atretic segment/segments of the IVC on contrast-enhanced CT or MR angiography [5,7]. Associated findings such as venous collaterals between upper and lower segments of the interruption or stenosis, azygos/hemiazygos continuation, DVT below the obstructed segment, and varices may be indirect findings. Dilated azygos/hemiazygos veins on CT or MRI are supplementary findings in the diagnosis. Right paracardiac nodular opacity on chest roentgenogram or unusual reverse “U” loop at the level of the azygos vein draining into the superior vena cava in transfemoral right heart catheterization as a sign of the azygos continuation also may be clues to the diagnosis [12]. Interrupted IVC with azygous continuation also can be diagnosed by the “double vessel” sign on prenatal ultrasound [19]. Interrupted or stenotic lesions of the IVC can be treated by interventional procedures, as was true in our patients [20]. Anomalies of the IVC occur in less than 1% of patients [21] and infrahepatic IVC interruption with azygos continuation is a rare congenital anomaly. The infrahepatic IVC may continue as the azygos [8] or hemiazygos vein, intrathoracic veins [5],

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

263

Fig. 5. 24-year-old man had suprahepatic stenosis of the inferior vena cava (IVC), presenting with bilateral lower extremity varices and leg swellings (A) coronal curved planar thin MIP image shows suprahepatic stenotic segment of the IVC (arrow), aneurysm of the paravertebral vein (open arrow). (B) Axial thin slab CT image shows ‘Y’-shaped web in the suprahepatic IVC, and dilated azygos vein (open arrow). (C) Axial MIP CT image in thick (35 mm) slab shows intrahepatic collateral veins (black arrows) between the hepatic veins (open arrows). (D) Axial MIP CT image in thick (30 mm) slab shows paravertebral (arrows) and epidural (double arrow) venous collaterals.

or anomalous intrahepatic veins [7]. The hepatic segment of the IVC drains directly into the right atrium [3]. Its prevalence is 0.6–2.0% in patients with congenital heart disease and less than 0.3% among otherwise normal patients [22]. In present study prevalence of the interruption or congenital stenosis of the IVC was found at 0.15%. This rate is lower than 0.3–0.6% of other groups which include pediatric and perinatal groups of patients [3–5,22]. Neonatal and pediatric group of patients were not included in our study. We thought that lower prevalence of our results may be due to the difference in the study population. Interrupted IVC usually involves suprarenal segment and is mostly accompanied with azygous or hemiazygos continuation and majority of the cases are accepted previously as an asymptomatic variation [3,5,12,23]. Infrarenal interrupted

or absent IVC also has been reported [12]. With obstruction of the IVC, venous blood from the inferior part of the body returns to the heart through four major collateral pathways: deep, intermediate, superficial, and portal [10,23]. In our series, collateral circulation was observed through all four pathways: retroperitoneal perirenal-renal capsular, paraspinal and intraspinal (deep); the left gonadal vein to the renal vein or IVC (intermediate); internal iliac vein to the hemorrhoidal plexus through the inferior mesenteric vein (portal); and superficial (abdominal wall). Recent reports revealed that there is more number of symptomatic cases associated with interruption or stenosis of the IVC [24–26]. Recent reports also points out that there is an association between the interruption of the IVC and lower-extremity

264

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

Fig. 6. 45-year-old woman had suprahepatic stenosis of the inferior vena cava (IVC), presenting with bilateral lower extremity varices (A) coronal curved planar thin MIP image shows suprahepatic stenotic segment of the IVC (double arrows), paravertebral collateral veins drain into azygos vein (arrow), dilatation of the azygos and hemiazygos veins (open arrows). Some distorsion is seen in the figure (A) because of a curved planar reconstruction of the image for tracing the veins. Coronal (B) and axial (C) thin-slab MIP CT angiographic images showing abdominal wall collaterals (arrows, A and B) drain into suprahepatic IVC via dilated diaphragmatic collateral veins (arrowheads, C).

venous insufficiency [6,25], or interrupted IVC alone can be a risk factor for the development of deep vein thrombosis or pulmonary embolism [8,10–25]. Obernosterer et al. [26] searched 97 patients with lower extremity DVT and found that 5 patients had hypoplastic segment or missed renal/infrarenal segment of the IVC in 31 patients with iliac vein involvement. Recurrent DVT caused by congenital interruption of the IVC together with heterozygous factor-V Leiden mutation also was reported [8]. In our study 8 of the 12 patients (67%) with interruption or congenital stenosis of the IVC were symptomatic because of DVT, collateral circulation, and varices with DVT. This is a high rate than previously reported studies [3,5]. In our study, four of the patients presented with DVT, and this patient group was relatively young with a mean age of 23.8 ± 7.8 years (range, 14–30 years). Factor-V Leiden mutation and antithrombin deficiency

was identified in one patient each. Our results also suggest that anomalies of the IVC could be suspected in some cases of DVT, especially if thrombosis is recurrent, bilateral, and involved the iliac veins, or is seen in young patients (≤30 years of age) [26]. However, in a recent report, incidence of IVC agenesia was found about 5% in young patients affected by lower extremity DVT [3,5]. In one of our cases with heterotaxy syndrome, left isomerism and polysplenia, double IVC and azygos and portal continuation by abnormal collaterals were identified (Fig. 4). Suprahepatic IVC stenosis is commonly seen at the diaphragmatic level, and collateral circulation can be through the azygos/hemiazygos vein, intrahepatic, or abdominal wall collateral veins. These collaterals drain at the diaphragmatic level into the IVC at the upper level of the stenosis or to the SVC as in our 1 case. Suprahepatic IVC stenosis or occlusion and classi-

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

cal Budd-Chiari syndrome are considered separate entities. The first instance was called obliterative hepatocavopathy because of different epidemiologic and clinical features [27]. Knowledge of anomalies of the IVC also can help an interventional radiologist plan endovascular treatment when DVT develops in such patients. Identification of an interruption or stenosis of the IVC as a possible underlying cause in a patient presented with bilateral lower extremity varices or abdominal venous collaterals gives us a chance for early treatment before chronic status. Knowledge of the presence of variant venous anatomy also is important for surgical and interventional procedures [1]. There can be procedural difficulties during right heart catheterization [23], electrophysiologic studies [23], cardiopulmonary bypass surgery [23], femoral vein catheter advancement, IVC filter placement, and temporary pacing through the transfemoral route. When interruption or stenosis of the IVC is identified in a patient, associated findings should be evaluated. If well-developed azygos/hemiazygos continuation is present, this patient presumably will be asymptomatic and knowledge of presence of this variation is not important except before surgical or interventional procedures. If well-developed azygos/hemiazygos continuation is not present, these type anomalies are presumably symptomatic. Presence of acute or recurrent deep vein thrombosis, diffuse varices, varicocele, hemorrhoids, venous aneurysm, or venous collaterals (including the abdominal wall), in a relatively younger patient can be a clue to interruption or congenital stenosis of the IVC. The main limitation of this study is that number of patients is not large, which limits the drawing of conclusive results. The retrospective nature of collection of some of the data also is a limitation. But rarity of the interruption or stenosis of the IVC makes it very hard to conduct studies with a larger patient population. And to the best of our knowledge, our study comprises one of the largest patient groups on the subject in the literature. 5. Conclusion In conclusion, interruption or stenosis of the IVC are rare on routine abdominal CT examinations and may cause different clinical findings depending on the variant drainage pattern or collaterals. Interrupted IVC is commonly asymptomatic if associated with well-developed azygos/hemiazygos continuation, whereas commonly symptomatic if well-developed azygos/hemiazygos continuation is not present or drainage of the interrupted IVC is mainly from collaterals. Presence of acute or recurrent deep vein thrombosis, diffuse venous collaterals including abdominal wall, varices, varicocele, hemorrhoids, or venous aneurysm in a relatively young patient is quite frequently seen in patients with interruption or congenital stenosis of the IVC and can be a clue for its diagnosis on CT or MRI. Acknowledgment ¨ The authors thank Unal G¨unes¸ (Grapher, Adana) for their assistance with drawing illustrations in this study.

265

References [1] Mathews R, Smith PA, Fishman EK, Marshall FF. Anomalies of the inferior vena cava and renal veins: embryologic and surgical considerations. Urology 1999;53(5):873–80. [2] D’Aloia A, Faggiano P, Fiorina C, et al. Absence of inferior vena cava as a rare cause of deep venous thrombosis complicated by liver and lung embolism. Int J Cardiol 2003;88(2–3):327–9. [3] Minniti S, Visentini S, Procacci C. Congenital anomalies of the venae cavae: embryological origin, imaging features and report of three new variants. Eur Radiol 2002;12(8):2040–55. [4] Boffa GM, Chioin R, Stritoni P, et al. Azygos or hemiazygos continuation of the inferior vena cava. An angiographic findings of 10 cases. G Ital Cardiol 1980;10(8):1063–8 [Italian]. [5] Bass JE, Redwine MD, Kramer LA, Huynh PT, Harris Jr JH. Spectrum of congenital anomalies of the inferior vena cava: cross-sectional imaging findings. Radiographics 2000;20(3):639–52. [6] Okuda K. Membranous obstruction of the inferior vena cava (obliterative hepatocavopathy. J Gastroenterol Hepatol 2001;16(11):1179–83. [7] Fishman EK. From the RSNA refresher courses: CT angiography: clinical applications in the abdomen. Radiographics 2001;21:3–16. [8] Schneider JG, Eynatten MV, Dugi KA, Duex M, Nawroth PP. Recurrent deep venous t hrombosis caused by congenital interruption of the inferior vena cava and heterozygous factor V Leiden mutation. J Intern Med 2002;252(3):276–80. [9] Raju S, Hollis K, Neglen P. Obstructive lesions of the inferior vena cava: clinical features and endovenous treatment. J Vasc Surg 2006;44(4):820–7. [10] Gayer G, Luboshitz J, Hertz M, et al. Congenital anomalies of the inferior vena cava revealed on CT in patients with deep vein thrombosis. AJR Am J Roentgenol 2003;180(3):729–32. [11] Zhang L, Yang G, Shen W, Qi J. Spectrum of the inferior vena cava: MDCT findings. Abdom Imaging doi:10.1007/s00261-006-9137-5. [12] Vijayaraghavan SB, Raja V, Chitra TV. Interrupted inferior vena cava and left-sided subrenal inferior vena cava: prenatal diagnosis. J Ultrasound Med 2003;22(7):747–52. [13] Ramanathan T, Hughes TM, Richardson AJ. Perinatal inferior vena cava thrombosis and absence of the infrarenal inferior vena cava. J Vasc Surg 2001;33(5):1097–9. [14] Drouillard J, Bruneton JN, Elie G, et al. Congenital malformations of the inferior vena cava. Embryological, anatomical and radiological study. J Radiol Electrol 1978;59(12):669–77. [15] Bass JE, Redwine MD, Kramer LA, Harris Jr JH. Absence of the infrarenal inferior vena cava with preservation of the suprarenal segment as revealed by CT and MR venography. Am J Roentgenol 1999;172(6): 1610–2. [16] Oguzkurt L, Tercan F, Ozkan U, Koc Z. Successful endovascular treatment of interrupted inferior vena cava in a pediatric patient. Cardiovasc Intervent Radiol 2006;29:446–9. [17] Paksoy Y, Gormus N. Epidural venous plexus enlargements presenting with radiculopathy and back pain in patients with inferior vena cava obstruction or occlusion. Spine 2004;29(21):2419–24. [18] Koc Z, Ulusan S, Oguzkurt L, Serin E. Symptomatic interrupted inferior vena cava: report of a case presenting with hematochezia. Br J Radiol 2006;79:e24–8, doi:10.1259/bjr/31792102. [19] Sheley RC, Nyberg DA, Kapur R. Azygous continuation of the interrupted inferior ena cava: a clue to prenatal diagnosis of the cardiosplenic syndromes. J Ultrasound Med 1995;14(May (5)):381–7. [20] Razavi MK, Hansch EC, Kee ST, Sze DY, Semba CP, Dake MD. Chronically occluded inferior venae cavae: endovascular treatment. Radiology 2000;214(January (1)):133–8. [21] Koc Z, Ulusan S, Oguzkurt L, Tokmak N. Venous variants and anomalies on routine abdominal multi-detector row CT. Eur J Radiol 2007;61: 267–78. [22] Sadler TW. Cardiovascular system. In: Langman’s medical embryology. 6th ed. Baltimore, MD: Williams & Wilkins; 1990. p. 217–20. [23] Pittman C, Reddy M, Reddy ER. Radiological evaluation of inferior vena cava obstruction: pictorial essay. Can Assoc Radiol J 1999;50(6): 376–83.

266

Z. Koc, L. Oguzkurt / European Journal of Radiology 62 (2007) 257–266

[24] Chung JW, Yoon CJ, Jung SI, et al. Acute iliofemoral deep vein thrombosis: evaluation of underlying anatomic abnormalities by spiral CT venography. J Vasc Interv Radiol 2004;15(3):249–56. [25] Hartung O, Otero A, Boufi M, et al. Mid-term results of endovascular treatment for symptomatic chronic nonmalignant iliocaval venous occlusive disease. J Vasc Surg 2005;42(6):1138–44.

[26] Obernosterer A, Aschauer M, Schnedl W, Lipp RW. Anomalies of the inferior vena cava in patients with iliac venous thrombosis. Ann Intern Med 2002;136(1):37–41. [27] Okuda K, Kage M, Shrestha SM. Proposal of a new nomenclature for BuddChiari syndrome: hepatic vein thrombosis versus thrombosis of the inferior vena cava at its hepatic portion. Hepatology 1998;28(5):1191–8.