Trisomy 18

As of January 2016, Trisomy 18 is not on the Recommended Uniform Screen Panel (RUSP). The RUSP is created by the Health Resources and Services Administration, and states use this list to guide what conditions they screen for on newborn screening. However, testing can be done on newborns if there is a concern for trisomy 18. Trisomy 18 can be diagnosed through fluorescence in situ hybridization (FISH) testing, karyotype, or chromosomal microarray. Your healthcare provider may choose one type of test or another based off of your insurance, turnaround time, and how strong his/her suspicion is Trisomy 18.

There are a few types of genetic tests that can diagnose Trisomy 18. Trisomy 18 can be diagnosed through fluorescence in situ hybridization (FISH) testing, karyotype, or chromosomal microarray. Your healthcare provider may choose one type of test or another based off of your insurance, turnaround time, and how strong his/her suspicion is Trisomy 18.

At least 1 abnormality is found in 90% of pregnancies with Trisomy 18, and around half of babies with Trisomy 18 have two ultrasound findings. The finding could vary from inadequate growth (intrauterine growth restriction) to a heart defect. Other findings are increased nuchal translucency, decreased or absent nasal bone, choroid plexus cysts (small cysts in brain), hands held with overlapping fingers, omphalocele (opening in abdominal wall), single umbilical artery, rocker bottom feet and polyhydramnios.