Many fetuses with Down syndrome are now prenatally diagnosed by karyotyping done because of advanced maternal age or abnormal triple screen test or fetal ultrasonographic findings.
triple screen test or fetal ultrasonographic findings.
If not prenatally diagnosed, most patients with Down syndrome are usually recognized at birth owing to characteristic physical findings.
Diagnosis of cardiac disease in infants with Down syndrome is not always obvious; in fact, clinical examination in the newborn period may be entirely normal. The alerting signs are poor feeding, easy fatigability, dyspnea, diaphoresis, cyanosis, and a cardiac murmur. However, some infants are asymptomatic if they are not experiencing congestive cardiac failure. Therefore, any infant with Down syndrome needs careful evaluation by current techniques such as echocardiography, Doppler flow analysis, etc.
Congenital gastrointestinal disease:
Duodenal obstruction occurs more frequently in infants with Down syndrome. The infant may present with bile stained vomiting, abdominal distension and a visible peristaltic wave. A "double bubble sign" characterizes the abdominal radiograph. The obstruction may be caused by congenital atresia, intrinsic stenosis, or extrinsic stenosis secondary to annular pancreas or malrotation of the bowel with bands. In the neonatal period, these lesions may constitute surgical emergencies.
Other malformations that can occur are:
- Hirschsprung disease
- Esophageal atresia
- Pyloric stenosis
- Diverticulum of the stomach
- Malrotation of the bowel
Hematological disease:
The incidence of leukemia is higher in infants with Down syndrome. Other disorders described in newborns include:
- Polycythemia
- Thrombocytopenia
- Erythroblastosis fetalis
Ophthalmologic problems:
Nystagmus and stabismus occur frequently in the newborn period and require consultation to rule out corneal opacities. Other ocular problems seen are:
- Refractive error
- Blepharoconjunctivitis
- Cataracts
- Keratoconus
- Retinal pathology
- Optic nerve hypoplasia
An abnormality detected on physical examination or poor visual tracking requires further investigation.
Urogenital abnormalities:
These include:
- Micropenis
- Cryptorchidism
- Hypospadius
- Anomalies of the kidneys and ureters
Endocrine abnormalities:
Persistent primary congenital hypothyroidism commonly occurs in newborns with Down syndrome. Thus, thyroid screening which is so important for all infants, is particularly relevant for infants with Down syndrome.
Ear problems:
There is an increased incidence of congenital sensorineural hearing loss in children with Down syndrome, so a hearing screen is recommended before discharge. Middle ear effusions may also be present.
| Cardinal features in neonates |
- Poor Moro reflex (85%)
- Hypotonia (80%)
- Flat facial profile (90%)
- Upslanted palpebral fissures (80%)
- Abnormal ears (60%)
- Excess skin on the back of neck (80%)
- Transverse palmar crease (45%)
- Hyperextensible joints (80%)
- Dysplasia of pelvis (70%)
- Fifth finger clinodactyly (60%)
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Six or more of the above features should be present for making a diagnosis clinically. Sometimes the findings may be subtle and may be missed. Also the findings can be confounded by prematurity or ethnicity.
IMPORTANT STEPS AFTER SUSPECTING DOWN SYNDROME IN A NEONATE:
- Establish diagnosis
- Thorough clinical examination to observe for congenital heart disease or gastrointestinal malformation
- Inform the parents in a supportive way
- Laboratory orders:
- Chromosomal karyotype
- Thyroxine
- TSH
- Complete blood count
- Differential count
- Platelet count
- Nucleated RBC count
- Echocardiography
- Hearing screen
- Funduscopy
- Discuss diagnosis and management plan with parents
- Refer parents to an infant intervention program and to a support group
- Conduct a follow-up meeting with family
