Potentially serious complications — The most serious complications of Down syndrome include heart defects, blood disorders that can include leukemia (cancer of the blood), and immune system problems. Heart defects — Approximately half of all babies with Down syndrome are born with (often repairable) heart defects.

The most common live-born human aneuploidy is trisomy 21, which causes Down syndrome (DS). Dosage imbalance of genes on chromosome 21 (Hsa21) affects complex gene-regulatory interactions and alters development to produce a wide range of phenotypes, including characteristic facial dysmorphology.

Some of the children with Mosaic Down syndrome that we know do not actually look as if they have Down syndrome – the usual physical features are not obvious. This raises some important and difficult social issues and identity issues for both parents and children, which parents have discussed with us.

An ultrasound can detect fluid at the back of a fetus’s neck, which sometimes indicates Down syndrome. The ultrasound test is called measurement of nuchal translucency.

Conclusion. Ultrasound scans aren’t a full-proof way of testing for Down syndrome in babies. They can detect some indications of potential markers that are commonly seen in Down Syndrome babies but can’t give a definitive answer. A Detailed Anomaly Scan done at 20 weeks can only detect 50% of Down Syndrome cases.

Pyelectasis is considered an ultrasound “marker,” which increases the chance that the baby may have Down syndrome. Although Down syndrome can occur in any pregnancy, the chance for Down syndrome increases with the mother’s age.

The most commonly studied soft markers of aneuploidy include a thickened nuchal fold, limb shortening, mild fetal pyelectasis, echogenic bowel, echogenic intracardiac focus (EIF), choroid plexus cyst (CPC) and single umbilical artery.

An echogenic intracardiac focus (or EIF) is a small bright spot seen on a developing baby’s heart during an ultrasound. The cause of EIF is unknown, but the condition is generally harmless. EIF is considered a normal pregnancy variation, but prenatal screening tests may be desirable to test for any abnormalities.

Fetal ultrasound during pregnancy can also show the possibility of trisomy 13 or 18. But ultrasound is not 100% accurate. Problems caused by trisomy 13 or 18 may not be seen with ultrasound. After birth, your baby may be diagnosed with a physical exam.