Abstract
BackgroundThe azygos venous system consists of the azygos vein on the right side and the hemiazygos and accessory hemiazygos on the left side. The azygos vein runs through the abdominal cavity along the right side of the vertebral bodies, in a cranial direction, passes through the diaphragm and reaches the mediastinum, where it forms the arch of the azygos which flows into the superior vena cava. Along its course, the azygos vein communicates with the intercostal veins on the right, the hemiazygos vein that collects blood from the left lower intercostal veins, and accessory hemiazygos vein that drains into the left upper intercostal veins. The last two, at the level of the seventh thoracic vertebra, unite and end in the azygos vein. The accessory hemiazygos vein is normally included in the length between T4 and T8. The embryological origin of the accessory hemiazygos vein is the result of an expansion in the direction of the cranial hemiazygos vein, which comes from the left upper sovracardinale vein (Dudiak et al. in Semin Roentgenol 24(1):47–55, 1989; Radiographics 11(2):233–246, 1991; Webb et al. in Am J Roentgenol 139(1):157–161, 1982).FindingsThis case report describes a rare variant of azygos vein system identified in prenatal diagnosis and confirmed by postnatal ultrasonography.ConclusionsThe observation of the patient has excluded hemodynamic alterations associated with vascular anomaly.
Highlights
The azygos venous system consists of the azygos vein on the right side and the hemiazygos and accessory hemiazygos on the left side
Our study has focused on a 27-year-old woman, in first pregnancy at a gestational age of 38 weeks, who has been submitted to fetal echocardiography
The prenatal ultrasonography with color Doppler has showed a hemiazygos accessory vein that, from the diaphragmatic dome, joining with the superior intercostal vein, seemed to drain into the venous trunk brachial-cephalic left (Fig. 3). We have assumed it was a rare variant of the azygos vein system: the hemiazygos and accessory hemiazygos veins form common channels which drain into the brachiocephalic vein (Fig. 1)
Summary
The azygos venous system consists of the azygos vein on the right side and the hemiazygos and accessory hemiazygos on the left side. Conclusions: The observation of the patient has excluded hemodynamic alterations associated with vascular anomaly. The prenatal ultrasonography with color Doppler has showed a hemiazygos accessory vein that, from the diaphragmatic dome, joining with the superior intercostal vein, seemed to drain into the venous trunk brachial-cephalic left (Fig. 3). We have assumed it was a rare variant of the azygos vein system: the hemiazygos and accessory hemiazygos veins form common channels which drain into the brachiocephalic vein (Fig. 1)
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