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Acta Biomed 2023; Vol. 94, N. 5: e2023238 DOI: 10.23750/abm.v94i5.15085 © Mattioli 1885
Case report
A remarkable case report of an interrupted inferior vena
cava with hemiazygos and transhepatic continuation
Federica Masino1, Gianmichele Muscatella1, Manuela Montatore1, Rossella Gifuni1,
Giuseppe Guglielmi1,2,3
1Department of Clinical and Experimental Medicine, Foggia University School of Medicine, Foggia, Italy; 2Radiology
Unit, “Dimiccoli” Hospital, Barletta, Italy; 3Radiology Unit, Hospital IRCCS Casa Sollievo della Sofferenza, San Giovanni
Rotondo, Italy
Abstract. Inferior vena cava (IVC) interruption with azygos/hemiazygos continuation is an extremely
uncommon congenital vascular anomaly, which may present with multiple variants. As a result, it is chal-
lenging to find in the literature the same anatomical variant. We report a unique case of an interrupted IVC
with hemiazygos and transhepatic continuation in an 83-year-old female patient. e case was evaluated by
performing Computed Tomography (CT) as imaging modality, with a multiphase protocol, able to detect ac-
curately this complex vascular anomaly. e purpose of this case report is not only to present this remarkable
case but also to briefly show the types of interrupted IVC, starting from the anatomy and the embryology
of the IVC and the azygos system, and to discuss the value of imaging in detecting the vascular anomaly.
(www.actabiomedica.it)
Key words: hemiazygos continuation, inferior vena cava, interrupted IVC, transhepatic continuation
Introduction
e Inferior Vena Cava (IVC) is a wide retrop-
eritoneal vein that drains deoxygenated blood from
the lower limbs, pelvic, and abdominal viscera to the
heart's right atrium (1).
e azygos venous system is a paired paraverte-
bral venous pathway in the posterior thorax that pro-
vides collateral circulation between the Superior Vena
Cava (SVC) and the IVC. e azygos, hemiazygos, ac-
cessory hemiazygos, and left superior intercostal veins
form an H-shaped arrangement which is typical of the
azygos venous system (2).
Interruption of IVC is a rare congenital anomaly
in which venous return from the lower body occurs
via azygos or hemiazygos venous system (3). e term
“ interrupted” is used to indicate a complete agenesis as
well as an anomalous course.
e anomaly primarily results from abnormal re-
gression or persistence of embryological veins (antero-
cardinal, post-cardinal, sub-cardinal, supra-cardinal,
and vitelline veins) that formed the five embryologic
segments of the final structure of the IVC (iliac, sub-
renal, renal, suprarenal, hepatic including suprahepatic
and retrohepatic) (1,3).
In most cases, the interruption of the IVC oc-
curs because of a failed anastomose between the right
subcardinal vein and the vitelline vein, resulting in
the agenesis of the infrarenal IVC and the interrup-
tion at the suprarenal segment. In this circumstance,
Acta Biomed 2023; Vol. 94, N. 5: e2023238
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the suprarenal IVC reroutes to drain via the azygos
vein, while the hepatic IVC only receives the hepatic
veins (4).
In other cases, the suprahepatic IVC may be ab-
sent or hypoplastic, resulting in direct drainage into
the right atrium. In this circumstance as well the azy-
gos system would be enlarged.
Subrenal interruption or absent IVC also has
been reported but is less common (2).
ese anatomical variants represent an asymp-
tomatic condition if associated with well-developed
azygos/hemiazygos continuation, but they may pre-
sent with recurrent deep vein thrombosis (DVT)
of the lower limbs, leg swelling, leg pain, varices
of lower extremities, abdominal pain, and rarely
hematochezia.
e interruption of the IVC may be isolated or
associated with other anomalies, such as congenital
cardiac disease, polysplenia (left isomerism), abnormal
abdominal situs, and azygos lobe.
In an asymptomatic condition it is typically de-
tected incidentally in the early to middle ages of
life (5,6).
To study the vascular anomaly, imaging modalities
include echocardiographic techniques, Color-Doppler
imaging, CT-angiography, and ICV-angiography, that
help to detect interrupted ICV, to identify the anomalous
course of the main vessels and to evaluate the dilatation
of the azygos system caused by increased flow. Espe-
cially, angiography is important to recognize the exact
anatomy of the drainage for surgical purposes. ere-
fore, detection of these venous anomalies is significant
because it would hamper right heart catheterization via
the femoral vein approach as well as cardiopulmonary
bypass surgery and pacemaker placement (7).
Case presentation
An 83-year-old Caucasian woman came for the
first time to our department to undergo a Total-Body
CT with medium contrast administration for a lung
tumor follow-up. Other CTs were already performed
in other clinics, but reports were not brought to view
at the time of the investigation.
She referred to not having a prior history of
coronary artery disease, congestive heart failure,
hypertension, diabetes, or a history of deep venous
thrombosis.
e study protocol followed the investigation
motivation as per medical request and consequently, it
was not the most appropriate for the study of vascular
anomalies. erefore, it was performed a multiphase
examination including a first unenhanced scan, fol-
lowed by post-contrast scans including an arterial and
portal venous phase, with a 64-detector scanner. In
order to better evaluate the anomaly, post- processing
reconstruction on all planes (axial, coronal, sagit-
tal), also with MIP application, and 3D images were
obtained.
At first look, the most evident imaging find-
ing about the vascular anomaly concerned the non-
visualized IVC in the usual right side of the aortae.
In this case, the paired common iliac vein joined
a distended hemiazygos vein that received the left renal
vein to end continuing in the accessory hemiazygos
vein.
e enlarged accessory hemiazygos made a visualiz-
ing arch that followed externally the one of the aortae,
to join in the end the SVC, which appeared enlarged
as well (Figure 1).
e suprahepatic veins flew out directly into the
right atrium, but one of them passed entirely through
the liver and continued outside originating a transhe-
patic continuation, that joined the confluence between
the azygos vein and the right renal vein. From the
right common iliac vein, a wide atypical vein departed
joining the confluence. In this way, the connection be-
tween the azygos and hemiazygos veins was obtained
(Figure 2).
e azygos vein followed its typical connection
with the SVC through its arch, but its origin was
anomalous, considering it started after it overpassed
at L1-L2 level the diaphragmatic pillar from the con-
fluence between the right renal vein, the transhepatic
vein, and an anomalous vein. (Figure 3)
Acta Biomed 2023; Vol. 94, N. 5: e2023238 3
Figure 1. Portal phase of a Whole Body-CT scan with MIP application. a) sagittal plane showed the accessory hemiazygos arch
from the Superior Vena Cava (SVC) and the continuation of the hemiazygos vein. b) coronal plane showed the accessory hemiazy-
gos arch, the entire course of the hemiazygos vein flowing at the left side of the vertebral column, its origin from the common iliac
veins. At the L1-L2 level, the hemiazygos overpassed the diaphragmatic pillar (*) c) axial plane images showed the entire arch on
the left side of the aortae and the accessory hemiazygos arch joining the Superior Vena Cava. Blue: Superior Vena Cava; Light blue:
accessory hemiazygos arch.
Discussion
e interruption of the ICV with azygos system
compensation is a complex and rare vascular anomaly
that presents multiple variants.
In the case presented the patient had got: an in-
trahepatic interrupted ICV with the suprahepatic veins
flowing out directly in the right atrium; a transhepatic
continuation of one suprahepatic vein connected to the
azygos vein; an enlarged hemiazygos system as main
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Figure 2. Portal phase of Whole-Body CT scan. a) curved reformatted image of the transhepatic continuation of one of the
suprahepatic veins. ere was no shunt with the portal system, as there was no communication with the splenic-portal axes (colored
in orange) b) showed the anomalous vein originating from the right common iliac vein, the confluence of the right renal vein, and the
azygos vein, the transhepatic continuation. c) and d) showed respectively the origin from the right common vein and the continuation
in the liver. Green arrow: origin; Yellow arrow: confluence; Blue arrow: transhepatic continuation; Red asterisk: azygos vein.
Figure 3. Portal phase of a Whole-Body CT scan with MIP application. a) axial plane showed the typical azygos arch. b) axial plane
showed from right to left the azygos vein, the aortae, and the enlarged hemiazygos. c) coronal plane showed the azygos overpassing
the diaphragmatic pillar at the L1-L2 level and its confluence with the right renal vein and the transhepatic continuation. Yellow:
azygos; Red: aortae; Green: hemiazygos.
Acta Biomed 2023; Vol. 94, N. 5: e2023238 5
drainage system. All conditions are rare and unusually
to find simultaneously (7).
e role of imaging in the detection of this type of
vascular anomaly is essential: CT in the case presented
allowead a good differentiation of all vessels and the
detection of the type of variant as well as the enlarge-
ment of all the azygos system.
What makes this anatomical variant truly unusual
can be summarized as follows:
- the interruption of the ICV was intrahepatic
and not at a suprarenal level, which is the most
common variant.
- the compensating main vessel corresponded to
the accessory hemiazygos and the hemiazygos
vein, with the latter that totally substitutes the
absent ICV. erefore, it originated from the
two paired common iliac veins.
- the arch formed by the accessory hemiazygos
vein embracing that of the aorta.
- the continuation of the accessory hemiazygos
vein directly with the hemiazygos vein.
- the transhepatic continuation of one of the su-
prahepatic veins, originating an intrahepatic
shunt.
- the confluence among the azygos vein, the tran-
shepatic continuation, and the right renal vein.
- the connection through a collateral vein be-
tween the confluence above-mentioned and the
right common iliac vein, originating a shunt
between the azygos and the hemiazygos system
(Figure 4).
Hemiazygos' continuation of an interrupted IVC
has several variations, including three possible paths
for blood in the hemiazygos vein to reach the right
atrium. In the first paths, the hemiazygos vein joins
the azygos vein at T8–T9. In this route, the findings
at more cranial levels are like azygos continuation with
enlargement of the distal azygos vein, as well as the
enlargement of the hemiazygos vein itself. e sec-
ond path involves a persistent left SVC, and blood
flows from the hemiazygos vein into the accessory
Figure 4. 3D reconstruction of the main vessels involved in
this vascular anomaly from a posterior and anterior view (a)
compared to a schematic drawing of normal anatomy and the
aberrant abdominal venous pathways of this reported case (b).
a) showed the arch, the hemiazygos continuation until the di-
vision in the common iliac veins and the wide vein from the
right common iliac vein connecting the transhepatic continu-
ation, the right renal vein, and the azygos vein. In b) veins are
numbered as follows: 1 inferior vena cava IVC; 2 renal vein;
3 common iliac vein; 4 accessory hemiazygos arch; 5 hemiazygos
vein; 6 suprahepatic veins; 7 transhepatic continuation; 8 azygos
vein; 9 wide vein connecting the right common iliac vein with
the confluence of 2, 7 and 8.
hemiazygos vein and left SVC and then into the cor-
onary sinus, all of which are dilated. e third path,
which is the one reported in this case, the hemiazygos
vein drains to the accessory hemiazygos vein to join
into an usual right SVC (2,8).
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Correspondence:
Received: 7 August 2023
Accepted: 7 September 2023
Giuseppe Guglielmi, Prof, MD
Department of Clinical and Experimental Medicine, Foggia
University School of Medicine
Viale L. Pinto 1, 71121, Foggia (FG), Italy
Radiology Unit, “Dimiccoli” Hospital, Viale Ippocrate, 15,
70051 Barletta (BT), Italy
Radiology Unit, IRCCS “Casa Sollievo della Sofferenza”
Hospital
Viale Cappuccini 2, 71013 San Giovanni Rotondo (FG), Italy
E-mail: giuseppe.guglielmi@unifg.it
ICV interruption with hemiazygos continuation
is a benign condition and, in this case, as vasculariza-
tion was well compensated, no treatment was needed.
Otherwise, the knowledge of the condition was crucial
for the patient in case of necessary surgical interven-
tion (9).
In addition, a misdiagnosis could have been done
considering that this anomaly at chest x-ray in the pos-
terior anterior film could present as an enlargement of
the mediastinal shadow (that might be confused with
adenopathy of aortic pathology) while, in the lateral
film, ICV shadow should be absent; or at Transesoph-
ageal Echocardiography (TEE) the dilated azygos or
hemiazygos vein lies adjacent to the descending aorta
might mimic an aortic pathology (5,10).
Considering that interrupted ICV is commonly
associated with other congenital anomalies, especially
in the cardiac field, a prompt search for additional
pathologies was evaluated. Moreover, excluding por-
tosystemic shunting was important for determining
management as persistent congenital portosystemic
shunts could be associated with significant morbid-
ity. In the case reported, there was no correlation with
other congenital anomalies and there was no evidence
of an association with the tumor affecting the patient.
e two conditions can be considered independent.
In conclusion, we reported a case of a rare venous
anomaly characterized by an interrupted ICV with a
developed hemiazygos and transhepatic continuation.
Both conditions are extremely rare, and their combina-
tion is poorly described in the literature.
e presented case gave the occasion to empha-
size the importance of imaging in the detection of
complex vascular anomalies, such as the one described.
Physicians should be aware of this unusual vascular
anomaly both to avoid misdiagnosis and to aid surgical
intervention.
Inform Consent: Consent to participate and for publication. Writ-
ten informed consent for publication was obtained from the patient.
Conflict of Interest: Each author declares that he or she has no
commercial associations (e.g. consultancies, stock ownership, equity
interest, patent/licensing arrangement etc.) that might pose a con-
flict of interest in connection with the submitted article.
