Abdominal sonography in the evaluation of heterotaxy in children.

Heterotaxy is a rare congenital disorder characterised by abnormal viscero-vascular situs with either left or right isomerism that usually coincides with complex cardiac malformation. A precise diagnosis must be made for the selection of the most appropriate treatment. The diagnosis and evaluation of these conditions have been dependent on invasive studies such as angiocardiography, although more recently magnetic resonance imaging (MRI) has been advocated. In paediatric patients MRI is far from ideal because of the need for sedation and monitoring during the examination. The authors reviewed the modalities used in the evaluation of heterotaxy with emphasis on the use of ultrasonography, including pulse and colour flow Doppler imaging. A series of 14 children with heterotaxy is presented; ten with left abdominal isomerism (polysplenia) and four with right isomerism (asplenia). Results of abdominal sonography were compared with those of echo- and angiocardiography, surgery and autopsy. Of the ten children with left abdominal isomerism, two had no cardiac abnormalities. All those with right isomerism had a complex vitium. One patient with left abdominal isomerism proved to have right atrial isomerism. Some new reproducible patterns in viscero-vascular derangement are reported. The predictable patterns of left and right isomerism are outlined and atypical features discussed.