This was a 32-year-old primi, who was referred to assess the kidneys.

Her fetal echo showed some interesting findings.

4chamber and LV outflow tract images are given below:

The 3 vessel trachea views are given below:

The aorta is seen to the right of the trachea and the ductus arteriosus is seen to the left of the trachea, forming a ” U “.

Power Doppler shows a turbulent junction of the aortic and ductal arches suggestive of Kommerel’s diverticulum.

The aberrant left subclavian artery arising from the Kommerel’s diverticulum is seen in the next two pictures.

A short review of the aortic arch anomalies would be of great help.
Normally in fetal echocardiography, the transverse aortic arch is located to the left of the trachea.
This does not refer to the side of the midline on which the aorta descends.In a right aortic arch, the transverse aortic arch is to the right of the trachea.

A little bit of embryology with some line diagrams would be of help.

Edwards hypothetical theory of double aortic arch with regression or persistence of parts of the aortic arch would explain the various presentations.

Normal left sided arch and the corresponding 3 vessel view would be as follows.

Three main subgroups of right aortic arch abnormalities are described:

1. right aortic arch with right ductus

2.  right aortic arch with left ductus

 

1. double aortic arch, with an upside-down “N” appearance

Practically these can be divided into

1. those that cause a vascular ring around the trachea and esophagus ( causing compression) of these structures – this creates the retro-tracheal sling.

 

1. no vascular ring and no obstruction, because the ductus arteriosus courses to the right of the trachea – usually this mirror branching is associated with major CHD , especially TOF.

Left sided aortic arch with aberrant right subclavian artery would be another presentation.