Deep venous thrombosis: an unusual aetiology

Clinical History

A 36-year-old caucasian female patient, previously healthy, was admitted due to pain, swelling and redness of left leg. Venous Doppler ultrasound showed extensive deep venous thrombosis (DVT). In order to investigate possible causes of DVT, blood tests and abdominal and pelvic Computed Tomography (CT) were preformed.

Imaging Findings

Ultrasonography B mode and colour Doppler of left leg venous system showed popliteal, superficial and common femoral veins, as well as saphenous femoral junction and proximal saphenous vein dilated, non-compressible, filled by thrombotic material, with complete absence of flow (images 1 to 4).

Abdominal and Pelvic CT were preformed after intravenous contrast administration on arterial and portal phases.
Showed absence of the infrarenal segment of the IVC, the IVC being formed by the convergence of the renal veins and maintaining its normal aspect until the entry on the right atrium. The common iliac veins were also absent and the venous circulation until renal veins was performed by enlarged ascending lumbar and multiple collateral paravertebral veins, draining on the right to a marked dilated azygos vein and on the left to the hemiazygos (images 5 to 10).

Discussion

Deep venous thrombosis has a long list of causes which include as one of the less frequently found congenital anomalies of the IVC [1].

These unusual entities cause venous stasis – one of the three factors proposed by Rodolph Virchow as needed to develop thrombosis [1, 2].

An advanced knowledge of the complex development of the inferior vena cava is required to understand the several congenital anomalies that can be found [3].

This vein is the result of the complex development of three pairs of longitudinal venous primitive channels between the 6th and 8th embryonic week: the posterior cardinal, the subcardinal and the supracardinal [2, 4, 5]
In the end we have a right aortic venous channel composed of four segments: intra hepatic, prerenal, renal and infrarenal – this last segment is derived from complex anastomosis between several segments of the posterior and supracardinal veins.

One of the less frequently found is the absence of the infrarenal IVC [2, 4].
In fact is not clear if it really represents a congenital anomaly since several authors refer that it is unlikely to have one embryonic to cause it [2, 4]
The other theory purposes an acquired cause such as a postnatal venous thrombosis with posterior vein absorption [2, 4]

Patients with this diagnosis may suffer venous insufficiency or present like in this case with DVT. DVT usually presents as progressive leg swelling, redness and pain, signs and symptoms whose extension correlates with the location of the occluded veins. A palpable vein cord may be present if there is associated superficial vein involvement.

Doppler ultrasound can be useful if we have a relatively slim and gasless patient. Always followed by Angiographic CT.

Nowadays multi-detector computed CT is a high temporal and spacial resolution which allows obtaining venous vascular studies of extremely high quality.

The infrarenal segment of the IVC is absent and sometimes the common iliac veins too. The blood drainage from the legs is made through ascending lumbar and paravertebral veins draining on the right to azygos and left to hemiazygos veins, dilated.
The IVC is formed by the union of the renal veins and its prerenal and hepatic segments are normal.

The patient was treated medically with anticoagulation with good clinical evolution. Waiting for vascular surgery opinion.

Always suggest a complete investigation of possible causes for a DVT to your clinicians, which should include abdominal and pelvic CT.

Differential Diagnosis List

Final Diagnosis

Absence of infrarenal IVC

URL:	https://eurorad.org/case/9638
DOI:	10.1594/EURORAD/CASE.9638
ISSN:	1563-4086