Surveillance Protocol for Trisomy 18

Time Period

Surveillance Recommendations

Prenatal

Ultrasonography at 19 weeks gestation

Fetal echocardiography considered if known trisomy 18 diagnosis or abnormal ultrasound

Postnatal

Physical examination for external anomalies

Complete blood count with differential

Echocardiography

Total abdominal ultrasonography, including urinary system (48–72 hours after birth)*,†

Cranial ultrasonography and/or MRI

Early screening by pediatric ophthalmologist

Airway assessment, possibly including sleep study

Baseline serum AFP level

0–12 months of age

Total abdominal ultrasonography at 3, 6, 9, and 12 months of age

Serum AFP levels at 3, 6, 9, and 12 months of age

Frequent feeding assessments

Audiology examination at 6–8 months of age

Dental screening

1–4 years of age

Annual ophthalmologic evaluation

After 2 years of age, annual orthopedic examination and spinal x-rays

Serum AFP levels every 3–4 months

Abdominal ultrasonography every 3 months until 4 years of age

Dental evaluation every 6 months

4–7 years of age

Annual ophthalmologic evaluation

Annual orthopedic examination and spinal x-rays

Abdominal ultrasonography every 6 months

Renal ultrasonography every 3 months until 7 years of age

Dental evaluation every 6 months

7–12 years of age

Annual ophthalmologic evaluation

Annual orthopedic examination

Abdominal ultrasonography every 6 months until 12 years of age

Puberty

Clinical evaluation for seizures, behavioral changes, and normal sexual development, including menses in females‡

≥ 12 years of age

Annual ophthalmologic evaluation

Annual orthopedic examination

* If prenatal ultrasound showed or suggested hydronephrosis but postnatal ultrasound was normal, renal ultrasonography is done at 4 to 6 weeks of age.

† If urinary system anomalies are present on initial or subsequent ultrasonography, voiding cystourethrography is typically done.

‡ Risk of primary or secondary amenorrhea.

AFP = alpha-fetoprotein.

Adapted from Kepple JW, Fishler KP, Peeples ES: Surveillance guidelines for children with trisomy 18. Am J Med Genet A 185(4):1294–1303, 2021. doi: 10.1002/ajmg.a.62097

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