Azygous continuation of the IVC and hepatic steatosis

Case contributed by Dr Essam G Ghonaim

Presentation

A 45 years old male presented for CT scan of the abdomen for evaluation of hepatic steatosis with suspicious focal lesion depicted during US examination.

Patient Data

Age: 45
Gender: Male

Images showed diffuse fatty infiltration of the liver, with no detectable focal lesions.

The infra-renal IVC is seen on the left side. It drains both renal veins and it ascends to join the hemi-azygous vein, which drains into the azygous vein and this ascends in its usual retro-crural course to the chest.    

Imaged showed the infra-renal IVC is seen on the left side (long white arrows). It drains both renal veins (long red arrows) and it ascends to join the hemi-azygous vein (short red arrows), which drains into the azygous vein and this ascends in its usual retro-crural course to the chest (long green arrows). 

Case Discussion

The reported incidence of this anomaly is estimated to be 0.6-2 % of patients with congenital heart diseases and less than 0.3 % in otherwise normal individuals 1 2 3.

This anomaly results from failure of right sub-cardinal-hepatic anastomosis with atrophy of right sub-cardinal vein and shunting of blood from supra-cardinal-sub-cardinal anastomosis to cranial portion of supra-cardinal vein (retro-crural azygos vein) 2.

Imaging findings include: hepatic veins drain into right atrium. Renal veins drain into azygous (or hemi-azygous). This anomaly usually occurs with a right infra-renal IVC with azygos/hemi-azygos continuation (4), but it may also occur with other two variants:

(1) Left infra-renal IVC with azygos/hemi-azygos continuation 5 (as in this case).  

(2) Double infra-renal IVCs with two possibilities: EITHER both IVCs join at the renal level and continue as azygos vein) 6 OR (the right IVC continues as the azygos vein and the left one continues as the hemi-azygos vein) 7.

The clinical importance of this anomaly is in misinterpretation as right para-tracheal mass or retro-crural adenopathy, in being associated with heterotaxy syndromes and other congenital heart diseases and in pre-operative knowledge of the anatomy prior to planning cardio-pulmonary bypass and to avoid difficulties in catheterizing the heart 8 9.

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Case information

rID: 40416
Case created: 20th Oct 2015
Last edited: 22nd Apr 2016
Inclusion in quiz mode: Included

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