Int J Anat Res 2013, 03:174-77. ISSN 2321-4287
Case Report
DOU BLE IN FERIOR VEN A CAVA: A RARE BU T IM PORTAN T
ANATOM ICAL VARIATION
Zhou Yaw Loo
1, Namrata Jhummon-M ahadnac
2.
ABSTRACT
Address for Correspondence: Dr. Zhou Yaw Loo, Depart ment of Surgery, Box Hill Hospital, Nelson Road, M elbourne, VIC 3128, Aust ralia. Phone: +614 3033 5733. E-M ail: zhouyaw.loo@gmail.com
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* 1 M BChB, PG Dip Surg Anat , 2 B M ed Sci, M BBS, PG Dip Surg Anat .
1 & 2 Depart ment of Anat omy and Neuroscience, Universit y of M elbourne, Grattan St reet , Parkville,
M elbourne, Vict oria 3010, Aust ralia.
Background: Congenital variat ions of t he inferior vena cava are uncom m on and are usually det ect ed radiologi-cally or at post-m ort em . The present st udy describes t w o cases of double inferior vena cava, one encount ered at rout ine anat om ical dissect ion of a fem ale cadaver and t he ot her an incidental finding of a sim ilar variat ion on pre-operat ive CT scan. The presence of such venous variat ions m ay lead t o radiological m isdiagnosis, inad-ver t ent ligat ion during ret roper it oneal surger y and has im portant im plicat ions for t hrom boem bolic disease.
KEYW ORDS:Double infer ior vena cava; congenit al.
INTRODUCTION
Int ernat ional Journal of Anatomy and Research,
Int J Anat Res 2013, Vol 1(3):174-77. ISSN 2321- 4287
Received: 04 Dec 2013
Peer Review : 04 Dec 2013 Published (O):30 Dec 2013 Accepted: 14 Dec 2013 Published (P):30 Dec 2013
Internat ional Journal of Anat omy and Research ISSN 2321-4287
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174
The inferior vena cava (IVC) usually forms from t he union of bot h common iliac veins posterior t o t he right common iliac artery at t he level of L5 vertebra. It courses superiorly on t he right side of t he abdominal aorta, grooving t he bare area of t he liver, passing t hrough t he cent ral tendon of diaphragm at T8 vertebral level, and finally terminates in the right at rium of the heart [1].
Anomalies of t he IVC are fairly rare and t hought t o r esul t f r o m m i st akes i n t h e co m pl ex embryological basis of t his vessel [2,3]. The most common of IVC variat ions, t he duplicat ion of t he IVC, has a reported incidence of 0.2 % t o 3% in t he general populat ion [4,5,6] and w it h t he advent of more modern radiological modalit ies, many such cases have been described in t he literat ure [7]. Alt hough usually asympt omat ic and p icked u p at ou t p at i ent v isi t s, t hese variat ions can be potent ially dangerous in t he operat ive sett ing.
In t his st udy, w e present t w o rare cases of duplicat ion of t he inferior vena cava. The first case descr i b es a cad aver i c o ccu r r en ce o f duplicat ion of t he IVC reproduced in vivo and in t he second case, in a pat ient preparing for surgery highlight ing t he clinical relevance of t his variat ion. Finally, w e discuss t he embryologic basis of IVC variat ions and review t he clinical importance of t his unusual finding.
CASE REPORTS
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Along it s course, it received t ributaries from t he right IVC (via an abnormal venous anast omoses passing behind t he aorta) and t he left ovarian vein. The right ovarian vein joined t he right renal vein. Bot h renal veins drained int o t he right IVC, w hich w as for m ed f rom t he union of bot h common iliac veins. (Figure 1) The origin, course and territ ories of ot her vessels as w ell as kidneys and ureters did not show any variat ion.
Figure 1: Duplicat ed left IVC (1) runs parallel t o t he right IVC (9), com m encing at t he left com m on iliac vein (4)
and joins t he left renal vein (6) w hich em pt ies int o t he right IVC (9) by crossing ant erior t o t he abdom inal aorta
(10) . It recei ves t r i bu t ar ies f ro m r ight IVC via an abnorm al venous channel (2) and t he left ovar ian vein
(5). The right ovarian vein (8) can be seen draining int o t he right renal vein (7). Bot h t he com m on iliac veins are joined by a venous anast om osis (3).
Case 2:A 59 year-old man underw ent a staging CT scan as part of t he pre-operat ive w ork-up for radical prostatect omy after a posit ive biopsy for prostat ic adenocarcinoma. The scan revealed an incidental finding of a double inferior vena cava, sim ilar t o t he one descr ibed in Case 1. The duplicated left IVC can be seen originat ing from t he left common iliac vein, terminat ing at t he left renal vein, w hich t hen joined t he right IVC via a pre aort ic t runk as above. Bot h common i l iac vei n s w ere con n ect ed b y a v eno u s anast omosis (Figure 2).
Figure 2: Coronal view s of a CT scan show ing double infer ior vena cava in an asym pt om at ic pat ient . The var iat ion is very sim i lar t o figure 1, w it h t he duplicat ed l e f t I VC o r i gi n at i n g f r o m t h e l ef t co m m o n i l i ac, t er m inat ing at t he left renal vein w hich joins t he right IVC by crossing ant erior t o t he abdom inal aor ta.
DISCUSSION
Th e co m p l ex em br yo lo gi cal b asi s f o r t h e development of t he IVC account s for t he many variat ions reported and, indeed, many systems of classificat ions of IVC variat ions are based on t he embryological precursors t o t his vessel [2,3]. Th e m o st ack n o w l ed ged t heo r y o f t h e development of t he infra-renal segment of t he vena cava, t he Nomina Embryologica, describes t he successive appearance, anast om osis and regression of t hree paired em br yonic veins (po st er i o r card i n al , su b car d i nal an d supracardinal veins) bet w een t he 6t h and 10t h
w eek of embryonic life [8]. First t o appear are t he posterior cardinal veins: all but t heir most d ist al po r t i o n r egr ess and fo r m s t h e i l iac bifurcat ion. Next , t he subcardinal veins form anteromedial to t he posterior cardinal veins: t he right subcardinal forms t he suprarenal IVC w hile it s l ef t co unt er p ar t regresses. Last ly, t he su pracar din al veins devel op dor sal t o t he subcardinal veins, wit h the right vein forming the infrarenal IVC w hile t he left vein regresses [2,3]. Failure t o regress of any of t he t hree left venous counterpart s are t hought t o be responsible for congenital abnormalit ies of t he vena cava [9]. In t h e case o f d up licat i on of t h e IVC, t he persist ence of t he left supracardinal vein is t hought t o be t he cause [2,5]. The left IVC t hus formed is a mirror image of t he right receiving corresponding vessels: t hus t he ovarian vessels each joining t he IVC on it s ow n side. In our first case, as in most report s of duplicated IVC, t he left IVC usually crosses over t o join w it h it s right counterpart at t he level of t he renal vein [10], alt hough t h ere have been incidences of it crossing at a low er level [11].
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There have also been reported cases of t he left IVC draining int o t he right IVC via a pre aort ic t runk w hile t he left renal veins empt ies int o t he left IVC at a low er level [12].
Our dissect ion also show ed t hat apart from t he left renal vein connect ing t he left vena cava t o t he r ight , anot her venous connect ion exist bet w een t he t w o IVCs but t his t ime crossing behind t he aorta and these have been previously t hought t o represent t he anast omoses betw een t he supracardinal veins [13]. The caliber of t he t w o IVCs have also been t he subject of many st udies on t his variat ion and t here have been suggest ions of classifying IVC duplicat ion as per t he diamet er of each IVC and in our case, no significant difference in t he diam et ers w ere recorded [12].
The importance of describing t hese congenital abnorm alit ies lie in t he clinical im plicat ions, especially w hen most of t hese variat ions are found at rout ine clinical visit s [14]. It may create d i agn o st i c p r o bl em s w h ere i t m ay b e misinterpreted radiologically as a saccular aort ic aneurysm, aort o-lumbar lymphadenopat hy, left pyeloureteric dilatat ion, ret roperit oneal cysts or l oo p s o f sm al l b o w el [ 14,15] , l ead i n g t o unnecessary intervent ions and morbidit y. For inst ance, t here are report ed cases of surgical explorat ion for presumed metastat ic test icular car ci no m a b ased o n t h e CT f i n di n gs o f lymphadenopathy[16,17]. These can be avoided by t he use of low er limb int ravenous cont rast inject ion and CT interpret at ion during venous phase, w hich allow better opacificat ion of t he IVC [18]. The use of magnet ic resonance and digit al subt ract ion angiography m ay also be considered [4].
In addition, t he presence of a duplicated IVC may complicate ret roperit oneal surgery as it can be misident ified as a lumbar vein or a variant of t he internal spermat ic vein[6]. Therefore, it is crucial t o i d ent i f y su ch con geni t al var i at io n s preoperat ively t o avoid iat rogenic inj ur y or inadvertent ligat ion.
Ther e h av e b een r ep o r t ed cases o f t h ro m b oem b ol i c ev ent s in p at i ent s w i t h du pli cat ed IVC [ 19] . It is unclear w h et h er co ngen it al IVC var iat i o ns p red i sp o se t o t hromboembolism. The exact mechanism is
un-unknow n, alt hough it has been suggested t hat venous stasis plays a role[20]. In pat ient s w it h d eep v ei n t hr o m b osi s n ecessit at i ng caval interrupt ion, it is paramount t o ident ify such variat ions as an IVC filter needs t o be inserted int o bot h IVC t o prevent recurrent pulmonary embolism [19].
CONCLUSION
Double inferior vena cava is an uncommon but clinically im port ant congenit al variat ion. The ast ut e clinician needs t o be aw are of such malformat ion as it carries important diagnost ic and t herapeut ic pit falls.
Acknow ledgement s: Th e au t ho rs w oul d l i ke t o t hank Professor Chris Briggs and Dr Gerard Ahern for t heir valuable input in giving t he final shape of t his m anuscript .
Conflicts of Interests: None
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Int J Anat Res 2013, 03:174-77. ISSN 2321-4287
Z Y Loo et al., Double Infer ior Vena Cava: a rare but im por t ant anat omical variat ion.
How to cite this article
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Z Y Loo, Jhummon-M ahadnac N. DOUBLE INFERIOR VENA CAVA: A RARE BUT IM PORTANT ANATOM ICAL VARIATION. Int J Anat Res 2013;03:174-177.
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