Tests
1st tests to order
chromosomal karyotype
Test
Indicated when Down syndrome is suspected. Translocation results require testing the parents to determine future recurrence risks.
Standard trisomy 21 (extra chromosome 21) is caused by chromosome nondisjunction and occurs in 95% of cases. In about 4% to 5% trisomy results from a chromosome translocation, and the remaining 1% are mosaic with a combination of normal and trisomic cells.[5]
If there are existing postnatal karyotype results, do not order a duplicate test unless there is uncertainty about the existing result, e.g., the result is inconsistent with the patient’s clinical presentation or the test methodology has changed.[28]
Result
trisomy 21, Robertsonian translocation, or mosaicism
CBC with differential
Test
Should be ordered within 3 days of birth to assess for hematologic abnormalities such as transient abnormal myelopoiesis and polycythemia.[17]
Result
normal or hematologic abnormalities
echocardiogram
hearing test
Test
Hearing screen is required in all newborns in the US. Requirements may vary internationally; please consult local guidance.
Objective tests such as brainstem auditory evoked response or otoacoustic emission may be appropriate.[17]
If the newborn does not pass the screening tests, refer to an otolaryngologist to assess for middle-ear abnormality.[17]
Tympanometry may be required if the tympanic membrane is not visualized.[17]
If it is confirmed that the newborn is deaf or hard of hearing, referral to early intervention should be made within 48 hours.[17]
Result
normal or mild to profound hearing loss
thyroid function tests
Test
Thyroid function test is required in all newborns in the US. Requirements may vary internationally; please consult local guidance.
Both thyroid-stimulating hormone (TSH) and free thyroxine (T4) should be measured, as congenital hypothyroidism can be missed if only T4 is measured at newborn screening.[17]
A significant number of children with Down syndrome may have subclinical hypothyroidism, which presents as normal T4 with mildly elevated TSH.[17]
Discuss management with a pediatric endocrinologist if there are TSH or T4 abnormalities.[17]
Result
normal; normal T4 with mildly elevated TSH; or low T4 with elevated TSH
vision exam
Test
Should be done in the newborn period because 4% of children Down syndrome are born with congenital cataracts.[5] Cataracts can be assessed via a red reflex test.[17]
Nasolacrimal duct may be obstructed as a complication of midface hypoplasia, but it improves with age.
If lacrimal duct obstruction is present, refer for evaluation for surgical repair of the drainage system if not resolved by 9-12 months of age.[17]
Other abnormalities include strabismus (23% to 44%), accommodative esotropia, myopia, hyperopia, and blepharitis.[34]
Result
variable abnormalities or normal
Investigations to avoid
routine celiac screen
Recommendations
Do not routinely screen asymptomatic children with Down syndrome for celiac disease.[17]
Rationale
The American Academy of Pediatrics no longer recommends routine screening for celiac disease in all children with Down Syndrome, with testing only recommended in symptomatic patients (with regular assessment for presence of symptoms).[17] There is no evidence of benefit for routine screening of asymptomatic individuals.
routine cervical spine x-ray
Recommendations
Do not perform routine radiologic evaluation of the cervical spine in asymptomatic children with Down syndrome. [17]
Rationale
The American Academy of Pediatrics no longer recommends routine radiography for screening of potential atlantoaxial instability in all children with Down syndrome because current evidence does not support this in asymptomatic children.[17]
Tests to consider
abdominal x-ray
Test
Infants with Down syndrome (DS) may be born with a gastrointestinal (GI) defect such as duodenal or anal stenosis, or duodenal or anal atresia (5% to 12%).[17][31] Should be obtained in any newborn with DS presenting with vomiting, abdominal distention, or delay in stool passage.
Result
normal or congenital GI anomalies
Use of this content is subject to our disclaimer