Major anomalies in chromosomal disorders (aneuploidy)

Major structural anomalies listed above are found in around a quarter (25%) of all babies affected by a chromosomal disorder. This; cannot therefore be relied upon as a method of detecting affected babies. On the other hand, at least 50% of babies with conditions such as Down’s syndrome will have one or more soft marker. For more severe chromosomal disorders such as Trisomy 13 (Patau’s syndrome), at least 90% of babies will have one or more soft marker identifiable by using ultrasound.

Soft markers in chromosomal disorders

We have seen the major anomalies above. Let’s now look at these so-called soft markers. What are they? Here are some of them:

· Choroid plexus cysts (cysts in a part of the brain)

· Nuchal fold thickening (skin fold at the back of the neck)

· Echogenic bowel

· Single umbilical artery (there are normally two arteries)

· Rhizomelic limbs or abnormally short long bones ( humerus and/or femur)

· Echogenic intracardiac foci (also called ‘golf balls’)

· Renal pelvis dilatation (pyelectasis)

It cannot be emphasized enough that, whilst these soft markers are seen more frequently in babies with chromosomal disorders such as Down’s, the majority of babies found to have one of these will be completely normal. Let’s look at them one by one:

Next Page: Choroid Plexus Cysts (CPC)