Case 2 : Down’s Syndrome with AVSD and ARSA at 24 weeks

The case was referred to us for fetal echocardiography at 24 weeks, the patient already had a Level II at 18 weeks. On fetal echo we found a complete balanced Atrio-Ventricular Septal Defect (AVSD). It comprises of a atrial septum primum defect and a ventricular septal defect with a single common atrio-ventricular valve. It is best diagnosed in apical four chamber view when during diastole one can appreciate the absence of crux of the heart and during systole there is loss of offset of the tricuspid valve insertion on the septum. Antenatal diagnosis of AVSD when isolated is associated with trisomy 21 in 58% of cases.

Dr. Anupam Nanda and Dr. Rajinder Nanda 

The case was referred to us for fetal echocardiography at 24 weeks, the patient already had a Level II at 18 weeks.

On fetal echo we found a complete balanced Atrio-Ventricular Septal Defect (AVSD). It comprises of a atrial septum primum defect and a ventricular septal defect with a single common atrio-ventricular valve. It is best diagnosed in apical four chamber view when during diastole one can appreciate the absence of crux of the heart and during systole there is loss of offset of the tricuspid valve insertion on the septum. Antenatal diagnosis of AVSD when isolated is associated with trisomy 21 in 58% of cases.

Figure 1: Absent nasal bone

Figure 2: AVSD

The fetus also showed an aberrant right sub-clavian artery (ARSA). ARSA is a relatively new marker for trisomy 21. It is seen in 23.6% cases of down’s syndrome and in 1.02% euploid fetus. Ultrasound evaluation of right sub-clavian artery course and origin is feasible in 98% of cases in second trimester and is directly related to sonographic experience and inversely related to maternal body mass index.

Figure 3: ARSA