The Egyptian Journal of Radiology and Nuclear Medicine (2016) 47, 883–890

Egyptian Society of Radiology and Nuclear Medicine

The Egyptian Journal of Radiology andNuclearMedicine

www.elsevier.com/locate/ejrnmwww.sciencedirect.com

ORIGINAL ARTICLE

Congenital anomalies of the inferior vena cava and

iliac veins: A cross-sectional study by multi-detector

computed tomography

* Address: 27 Ahmad Foad Nour Str., Camp Caesar, Alexandria

21525, Egypt. Tel.: +20 (003)01001948320.

E-mail address: mohamed.shaban@gmail.com.

Peer review under responsibility of The Egyptian Society of Radiology

and Nuclear Medicine.

http://dx.doi.org/10.1016/j.ejrnm.2016.05.0030378-603X � 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Mohamed Samir Shaaban *

Diagnostic and Interventional Radiology Department, Faculty of Medicine, Alexandria University, Egypt

Received 29 February 2016; accepted 4 May 2016Available online 26 May 2016

KEYWORDS

IVC;

Iliac veins;

Anomalies;

Variations;

MDCT

Abstract Purpose: To study the prevalence of the anomalies of inferior vena cava and iliac veins

branching patterns by multi-detector CT.

Materials and methods: Retrospective analysis of the images of 1167 patients who underwent

contrast-enhanced MDCT examination of the abdomen and pelvis during the period from first

of November 2014 to the 31st of October 2015, with recording of the detected IVC and iliac veins

branching patterns anomalies.

Results: Of 1167 patients who underwent imaging, 1144 were included in the study. They included

571 males (50%) and 573 (50%) females, ages ranged from one year old to 90 years old, with a mean

of 49.7 years (±16.3). 918 patients (80%) had normal IVC and normal iliac veins branching pat-

tern, 110 cases showed isolated IVC anomalies with normal iliac veins branching pattern (49%),

110 showed isolated iliac veins branching anomalies (49%), and six patients showed combined

IVC and iliac veins anomalies (2%). No statistically significant sex correlation with the anomalies

was found.

Conclusion: Multi-detector CT can display different anomalies and variations in IVC and the iliac

vein, findings of potential clinical and operative importance in abdominal and pelvic surgeries.� 2016 The Egyptian Society of Radiology and Nuclear Medicine. Production and hosting by Elsevier.

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-

nd/4.0/).

1. Introduction

Anomalies of the IVC have been first described by Abernethyin 1793 when he described a case of congenital mesocaval

shunt and azygos continuation of the IVC in a child with com-

plex cardiac anomalies (1). Congenital anomalies of the IVChave been counted to be about 14 in number; however, onlyfew anomalies have clinical significance such as relatively highrate of thromboembolic accidents and ureteric obstruction

(1–3). IVC anomalies can also affect surgical or endoscopicinterventions to abdominal or pelvic pathologies (4,5).

Embryological origin of the inferior vena cava (IVC) is

complex and included appearance and disappearance of multi-ple abdominal and thoracoabdominal veins during the sixth to

Table 1 Correlation between patients sex and the IVC

anomalies.

Sex IVC

anomaly

Spearman’s

rho

Sex Correlation

coefficient

1.000 .021

Sig. (2-tailed) . .487

IVC

anomaly

Correlation

coefficient

.021 1.000

Sig. (2-tailed) .487 .

Significant if P< 0.05.

884 M.S. Shaaban

tenth week of gestation (1). During the 4th week of fetal life,paired posterior cardinal veins drain the caudal portion ofthe embryo. These veins are progressively replaced, first by

the sub-cardinal veins and later by the supra-cardinal veins.The hepatic IVC is formed by the right vitelline vein. Thesuprarenal IVC is formed by the right sub-cardinal vein, while

the infra renal IVC is formed by the right supra-cardinal vein.Anastomotic veins between the supra-cardinal and sub-cardinal veins form the renal segment of the IVC. Caudally,

the persistent posterior cardinal veins form the iliac veins(6,7) Fig. 1.

Typically the normal IVC extends from the right atrium ofthe heart downward to the right to the midline alongside the

abdominal aorta, down to the level of LV5 where it bifurcatesinto a common iliac vein on each side, each common iliac veinthen divides into an internal and an external iliac vein (8). Con-

genital anomalies of the IVC include Left IVC, Double IVC,

Fig. 1 Drawing illustrates the embryologic development of the IVC

(vertical red), and supracardinal (purple) veins – develop in succession o

regress (dashed colored lines), whereas others persist (solid colored lin

the suprarenal segment of the IVC, and the right supracardinal vein for

vitelline vein (green). Anastomotic channels (black) connect the various

anterior to the aorta forms the left renal vein (horizontal red line), w

normally regress. The supracardinal veins continue as the azygous an

posterior cardinal veins. AN = anastomosis, V = vein.

Retrocaval Ureter, Absence of the Infrarenal IVC, Retroaorticand Circumaortic Left Renal Vein, and interruption of the

IVC with Azygous or Hemiazygos Continuation (7).

. Three pairs of veins – the posterior cardinal (blue), subcardinal

n either side of the aorta (gray). Portions of these venous channels

es) to form the infrahepatic IVC. The right subcardinal vein forms

ms the infrarenal segment. The hepatic segment is derived from the

segments of the IVC. An intersubcardinal anastomosis that passes

hereas intersupracardinal and interposterior cardinal anastomoses

d hemiazygos veins; the iliac veins are derived from the persistent

Table 2 Correlation between patient sex and iliac veins anomalies.

Sex Iliac veins anomaly

Spearman’s rho Sex Correlation coefficient 1.000 �.163

Sig. (2-tailed) . .083

Iliac veins anomaly Correlation coefficient �.163 1.000

Sig. (2-tailed) .083 .

Significant if P < 0.05.

Table 3 Relative frequencies of the IVC anomalies in the studied group.

IVC anomaly Number Percentage within

the IVC anomalies (%)

Percentage within all

studied population (%)

Circum-aortic left renal vain 58 50 5.07

Retro-aortic left renal vein 46 40 4.02

Left sided IVC 4 3 0.35

Fenestrated IVC 3 2.5 0.26

Retro-caval ureter 3 2.5 0.26

Double IVC 2 2 0.17

Total 116 100% 10.14

Fig. 2 Axial contrast-enhanced CT with thin MIP reformatting in axial (a) and sagittal (b) planes, showing circum-aortic left renal vein

encircling the abdominal aorta anteriorly (yellow arrow) and posteriorly (green arrow).

Fig. 3 Axial contrast-enhanced CT with thin MIP reformatting in axial (a) and sagittal (b) planes, showing retro-aortic left renal vein

(blue arrow) passing posterior to the abdominal aorta.

Congenital anomalies of the inferior vena cava and iliac veins 885

Fig. 4 Coronal contrast-enhanced CT with thin MIP reformatting in axial plane (a) with the corresponding coronal VRT clip (b),

showing left sided IVC (yellow arrow) crossing to the left side of the abdominal aorta (green arrow).

Fig. 5 Coronal contrast-enhanced CT in the abdomen, showing

small fenestration within the IVC (yellow arrow) just above its

bifurcation.

886 M.S. Shaaban

With the widespread use of imaging techniques, especiallycomputed tomography (CT), incidentally discovered IVC

anomalies have increased, and recognition and reporting ofsuch anomalies have been proposed to decrease complicationsin abdominal surgeries, especially related to the kidneys, and a

detailed knowledge of these anomalies is crucial for IVC filterplacement, spermatic vein embolization, and adrenal or renalvenous sampling (9–11).

2. Aim of work

The aim of this work was to study the prevalence of the

anomalies of inferior vena cava and iliac veins branchingpatterns by multi-detector CT.

3. Patients and methods

3.1. Patients

This retrospective study was approved by the institutionalreview board of our hospital, and the requirements for

informed consent were waived.CT scans of all patients who had been referred to undergo

contrast-enhanced MDCT of the abdomen and pelvis regions,

during the period from the first of November 2014 to the 31stof October 2015 were retrospectively reviewed, by a seniorconsultant radiologist with 10 years experience in abdominal

imaging, with recording of the detected IVC and iliac veinsbranching patterns anomalies.

3.2. CT protocol

CT examinations were performed with 4 detectors CT scanner(bright speed, GE Healthcare, Milwaukee, Wisconsin, USA),16 detectors CT scanner (Brilliance, Philips Medical Systems,

Amsterdam, the Netherlands), and 46 detectors CT scanner(Siemens Perspective, Erlangen, Germany).

All patients received an intravenous dose of contrast med-

ium (iohexol, 300 mg I/mL – Omnipaque 300, GE Healthcare),with variable rate and amount, according to patient age,weight and CT examination. Slice thickness of the CT scans

ranged from 1 to 1.5 mm.Images were reviewed on Osirix Lite 7 software in Multi-

planar reformatting, Maximal intensity projection and Volume

rendering techniques.

3.3. Inclusion criteria

All patients underwent a contrast CT study of the abdomen

and pelvis that entailed enhancement of the IVC from the rightatrium to the bifurcation of the common iliac vessels, regard-less of the indications and technique of the CT examination.

a b

c d

Fig. 6 25-year old female patient with right hydronephrosis. CT examination of the abdomen and pelvis in delayed post-contrast phase

at the level of the kidneys (a), at LV4, and at LV5 showing moderate right hydronephrosis (a), with the ureter (yellow arrow) passing

posterior to the IVC (b) to run medial to it (c). (d) Coronal contrast-enhanced CT in the abdomen in MIP reformatting showing retro-

caval right ureter with backpressure effect.

Fig. 7 Axial (a) and coronal (b) contrast-enhanced CT, showing double IVC (yellow and green arrows).

Congenital anomalies of the inferior vena cava and iliac veins 887

3.4. Exclusion criteria

Patients who did not receive IV contrast opacifying the IVC

and iliac veins, patients with mass lesions grossly infiltratingthe IVC and/or iliac veins, the presence of congenital renalanomalies, and patients who underwent abdominal surgery

that changed the anatomy of the IVC and/or iliac veins.

3.5. Statistical analysis

Data were analyzed using IBM SPSS 20. Relative frequencies,means and standard deviations were calculated. Correlationbetween the sex and various anomalies was performed bySpearman Correlation test.

4. Results

CT scans of 1167 patients were retrieved. 23 cases wereexcluded from the study due to renal congenital anomalies(n= 14), lymphoma with massive lymphadenopathy com-

pressing the IVC and iliac veins (n= 5), complete situs inver-sus (n = 2) and two cases of large retroperitoneal pelvicmasses markedly compressing the iliac veins.

1144 were included in the study. Patients were 571 males(50%) and 573 (50%) females, ages ranged from one year to90 years, with a mean of 49.7 years (±16.3).

CT examinations included in this study were 364 routineCT Abdomen and Pelvis (32%), 325 Triphasic Liver CT (28%),246 CT Urography (22%), 170 CT Entero-colonography

Fig. 8 Coronal contrast-enhanced CT (a) with the corresponding coronal VRT image (b), showing the left renal vein (yellow arrow)

draining into the left common iliac vein (green arrow).

Fig. 9 Coronal contrast-enhanced CT, showing the left internal

iliac vein (yellow arrow) drains into the right common iliac vein.

Fig. 10 Coronal contrast-enhanced CT, showing the right

internal iliac vein (yellow arrow) drains into the left common

iliac vein.

888 M.S. Shaaban

(15%), 25 Multiphasic Pancreas (2%), nine CT Aortography(0.5%) and five Dynamic Adrenal CT (0.5%).

918 of the cases showed the normal typical anatomy of the

IVC and its normal branching into two common iliac veins,each in turn branching into an external and an internal iliacvein, constituting 80% of all 1144 cases included in this study.

Of the 226 cases which showed IVC and/or iliac veinsanomalies, 110 cases showed isolated IVC anomalies with nor-mal iliac veins branching pattern (49%), 110 showed isolatediliac veins branching anomalies (49%), and six patients showed

combined IVC and iliac veins anomalies (2%).There was no significant correlation between the sex and

the IVC anomalies (Table 1), or the iliac vein anomalies

(Table 2).Table 3 displays the IVC anomalies found in the studied

group and their relative frequencies, the most common of

IVC anomalies was circum-aortic left renal vein (n = 58), con-stituting 50% of all IVC anomalies and 5.07% of the studiedpopulation (Fig. 2), followed by retro-aortic left renal vein(n = 46), 40% of all IVC anomalies and 4.02% of the studied

population (Fig. 3), other IVC anomalies included left sidedIVC (3%) (Fig. 4), fenestrated IVC just above its bifurcation(2.5%) (Fig. 5), retrocaval ureter (2.5%) (Fig. 6) and double

IVC (2%) (Fig. 7).Regarding anomalies of iliac veins, they were divided into

three categories: the first was unilateral anomalies where

anomalous branching was found in one side in 46 cases(40%) (Fig. 8), bilateral anomalies in which anomalousbranching pattern was found in both sides in eight cases

(7%), and anomalies connecting the two sides with each otherin 62 cases (53%) (Figs. 9 and 10). Table 4 displays the differ-ent types of iliac veins anomalies.

Regarding the 6 cases with concomitant IVC and iliac veins

anomalies, the most IVC anomaly was retro-aortic left renalvein in 3 cases (50%), while no iliac vein anomaly was repre-sented more than once in the study sample Table 5.

5. Discussion

IVC and iliac vein congenital anomalies are complex and may

imply clinical and surgical significance. This was found in anumber of studies reporting cases with congenital anomalieswere correlated with venous varices in a child (Lesanu et al.

Table 4 Relative frequencies of the iliac veins anomalies in the studied group.

Category Iliac veins anomaly Number Percentage

(%)

Anomalies

connecting both sides

Some branches of the right internal iliac vein drain into left common iliac vein 19 16

The left internal iliac vein completely drains into the right common iliac vein 11 9

Some tributaries of the left internal iliac vein drain into right common iliac vein 8 7

The right internal iliac vein completely drains into the left common iliac vein 24 21

Total 62 53

Bilateral anomalies Some tributaries of each internal iliac vein drain into the ipsilateral external iliac vein 4 3

Both internal iliac veins completely directly drain into the IVC 3 3

An anomalous vein connects the left external and left internal iliac veins, and some tributaries

from the right internal iliac vein drain into the right external iliac vein

1 1

Total 8 7

Unilateral anomalies Fenestrated left common iliac vein 2 2

The left renal vein drain into the left common iliac vein 1 1

Some tributaries of the left internal iliac vein drain into the left common iliac vein 2 2

Some tributaries of the left internal iliac vein drain into the left external iliac vein 10 9

The left internal iliac vein directly drains into the IVC 1 1

Agenesis of the left common iliac vein 1 1

Some tributaries of the right internal iliac vein drain into the right common iliac vein 2 2

Some tributaries of the right internal iliac vein drain into the right external iliac vein 14 12

The right internal iliac vein directly drains into the IVC 4 3

Anomalous vein connecting the left external and left internal iliac veins 5 4

Anomalous vein connecting the right external and right internal iliac veins 3 3

The left internal iliac vein directly drains into the IVC, with some of its tributaries originating

from the left external iliac vein

1 1

Total 46 40

Table 5 Frequencies of the concomitant IVC and iliac veins

anomalies in the studied group.

Concomitant IVC and iliac veins anomalies Number

Circum-aortic left renal vein – some branches of the

internal iliac veins bilaterally drain into the ipsilateral

external iliac vein

1

Circum-aortic left renal vein – some branches of the left

internal iliac vein drain into the left external iliac vein

1

Left sided IVC – left internal iliac vein completely drain

into the right common iliac vein

1

Retro-aortic left renal vein – an anomalous vein

connects the left CIV and the Left renal vein

1

Retro-aortic left renal vein – left internal iliac vein

completely drain into the right common iliac vein

1

Retro-aortic left renal vein – right internal iliac vein

directly drain into the IVC

1

Congenital anomalies of the inferior vena cava and iliac veins 889

(12)), deep iliac vein thrombosis (Sarlon et al. (13)), andureteric obstruction (Shin et al. (14), Basok et al. (15) and

Abraham et al. (16)). Strauss et al. (17) concluded that aware-ness of retroperitoneal abnormal vessels is crucial to avoiddiagnostic pitfalls and intraoperative complications.

The current study did not correlate between venous anoma-lies and the clinical or operative implications; however, threeof the cases had retro-caval right ureters, with consequent

backpressure effect.Regarding the incidence of the congenital anomalies of

IVC, a review article by Smillie et al. (18) stated that IVCanomalies are present in about 4% of population, while in

the current study IVC anomalies in the current study were pre-sent in 10.14% of the studied population. Smillie et al. (18) and

Bass et al. (19), both stated the prevalence of duplication of theIVC, left-sided IVC, and azygos continuation of the IVC as0.2–0.3%, 0.2–0.5%, and 0.6% respectively. Bass et al. (19)

stated the prevalence of circum-aortic left renal vein andretro-aortic left renal vein as 8.7% and 2.1% respectively. Inthe current study, the incidence of left-sided IVC, azygos

continuation of the IVC, circum-aortic left renal vein, andretro-aortic left renal vein were 0.35%, 0.17%, 5.07%, and4.02% respectively.

Regarding the iliac vein anomalies, Shin et al. (20) showed

iliac vein variation prevalence of 20.9%, while in the currentstudy, iliac vein anomalies were present in only 4% of thestudied population. In Shin et al. (20), the prevalence of right

internal iliac vein joining the left common iliac vein was 2.1%,left internal iliac vein joining the right common iliac vein 0.2%,and Common iliac vein fenestration 0.4%. In the current

study, the prevalence of right internal iliac vein joining the leftcommon iliac vein was 2%, left internal iliac vein joining theright common iliac vein 1%, and Common iliac vein fenestra-tion 0.1%. The results of Shin et al. (20) and the current study

are near matched, despite the different sample size in bothstudies (2488 in Shin et al. (20), and 1144 in the current study).

6. Conclusion

Multi-detector CT can display different anomalies andvariations in IVC and the iliac vein, and findings of potential

clinical and operative importance in abdominal and pelvicsurgeries.

890 M.S. Shaaban

Conflict of interest

The author declare that they have no conflict of interest.

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