The Role of Ultrasound in the Prenatal Diagnosis of CdLS

The Role of Ultrasound in the Prenatal Diagnosis of CdLS

For parents who already have a child with Cornelia de Lange Syndrome (CdLS) and who want to have more children, prenatal ultrasound can provide a helpful evaluation of subsequent pregnancies. Research continues to support the low reoccurence risk for CdLS and ultrasound can be a source of reassurance and comfort to some parents.

Ultrasound is currently our best - and possibly our only - tool for prenatal diagnosis. There are a number of findings in CdLS that can be recognized prenatally. Probably the most reliable indicator is poor growth in a small fetus. Poor growth can be detected at ages greater than 25 weeks of gestation for most babies with CdLS, especially if there has been accurate dating with an earlier ultrasound.

For parents who have had a child with CdLS, an initial ultrasound examination may be recommended for all subsequent pregnancies at 18 weeks. The timing of this scan will allow a thorough study of the anatomy of the fetus, and also provide accurate dating of the pregnancy. In addition to the routine survey, the anatomy that should be examined particularly carefully includes the face, the hands, the heart, the arms, and the ventricles of the head. A second ultrasound study at 30 weeks could provide added reassurance that the fetus has grown normally, if needed.

An initial scan at 8 weeks would provide a very accurate estimate of the fetusí age, and this would allow a close monitoring of the growth. In addition a scan would also have to be performed at 18 weeks because the organs of the fetus are not completely formed and fetal anatomy cannot be seen clearly at eight weeks.

Anatomic abnormalities that have been described on prenatal studies of babies with CdLS include: limb abnormalities (particularly of the upper limbs), abnormal hearts, cleft lip, abnormal facial profile, diaphragmatic hernia, mild enlargement of the ventricles of the head, and gastrointestinal abnormalities.

The most distinctive of these abnormalities are those of the upper limb. Arm bones and fingers should be carefully examined and counted because these may be missing or abnormally short. The femur, feet, and arm bones should be measured to ensure that their lengths are within the normal range. There are tables of normal measurements that the person performing the ultrasound study should have.

In the face of a baby with CdLS, one might find cleft lip or palate, long eyelashes, a small chin, and a small upturned nose. In many of the children, there are abnormalities of the heart (ventricular septal defectsi atrial septal defects, hypoplastic aorta, persistent left superior vena cava, and tetralogy of Fallot).

The head of the baby with CdLS will tend to be short and small (microbrachycephaly) and so should be measured and compared to tables of non-normal measurements. The person performing the ultrasound study should also check to be certain that the baby does not have a diaphragmatic hernia or abdominal calcification (meconium peritonitis).

In many cases, babies with CdLS move much less than normal babies. The person doing the scan could perform a biophysical profile to provide an evaluation of the babies behaviour and responses.

Ultrasound is not a perfect tool to diagnose CdLS, nor is it a perfect tool to exclude the possibility of CdLS. Nonetheless, most children with CdLS have fairly severe abnormalities that can be detected prenatally by careful radiologists or obstetricians. It is anticipated that in almost all cases, scans performed on subsequent pregnancies will be normal. This should help parents find considerable joy and hope with these pregnancies, rather than anxiety and fear.

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