Diagnosing Trisomy 18 (Edwards Syndrome)

Overview:

Trisomy 18, also known as Edwards Syndrome, is a genetic condition caused by an extra chromosome 18. 

Diagnosis can be made prenatally (in utero) or after birth.

Why Early Diagnosis is Important: Allows for proactive medical management. Helps healthcare providers and families plan for care. Allows parents to get emotional support and counseling.

Get Advice: When you suspect a Trisomy 18 diagnosis, talk to a healthcare provider. Early consultation is key, medically and emotionally.

Brooke, a trisomy 18 child, wearing a yellow shirt

Prenatal Diagnosis Methods (In Utero):

 1. Ultrasound Screening:

(within weeks 11-20)

Can pick up on physical signs:

  • Heart defects
  • Growth delays
  • Fisted hands with overlapping fingers
  • Abnormal head shape and facial features
  • Rocker-bottom feet

2. Non-invasive Prenatal Testing (NIPT):

  • As early as 10 weeks gestation
  • Analyzes fetal DNA in the mother’s blood
  • Very accurate test for chromosomal anomalies including Trisomy 18.

3. Chorionic Villus Sampling (CVS):

  •  Performed 10-13 weeks gestation
  • Samples cells from the placenta for chromosomal testing.
  • Definitive diagnosis but small risk of miscarriage 

4. Amniocentesis: 

  • Performed at 15-20 weeks gestation.
  • Samples of amniotic fluid to test fetal chromosomes.
  • Definitive test with high accuracy but a small risk of complications.

Postnatal Diagnosis Methods (After Birth):

1. Physical Examination:

Doctors look for:

  • Low birth weight
  • Small head (microcephaly)
  • Small jaw (micrognathia)
  • Overlapping fingers
  • Severe developmental delays
  • Rocker-bottom feet

2. Karyotype Test:

A blood test to confirm chromosomal makeup. Shows the presence of extra chromosome 18.

3. Fluorescence In Situ Hybridization (FISH):

Rapid test to look at specific chromosomes in cells. Confirms chromosomal abnormality quickly.