Anemia of Prematurity - Portal Neonatal

• Blood type: The baby's blood type should be determined and compared with that of the
mother. Mothers with blood type O may have circulating antibodies to other red cell antigens
that can cross the placenta and cause hemolytic disease in a baby with a different blood type,
such as blood type A or B. Similarly, mothers who are Rh negative may have antibody to the
Rh antigen if they have not been treated with RhoGAM. Antibody to the Rh antigen causes the
most fulminant type of hemolytic hyperbilirubinemia, termed erythroblastosis fetalis in its most
severe form. ABO incompatibility can cause significant hemolysis as well. Minor antigens on
the baby's RBC are also susceptible to immune-mediated hemolysis from maternally acquired
antibody but usually to a lesser extent than the major antigens.
• Reticulocyte count: Babies typically have reticulocyte counts higher than older infants and
adults. However, significant elevation in the neonate's reticulocyte count (>7 mg/dL) can
indicate the presence of an ongoing hemolytic process.
• Direct Coombs test: This test assays for antibody on the RBC membrane. A positive result
indicates that antibodies are attached to the RBC, placing it at risk for immune-mediated
destruction. This is a qualitative test, so a positive result does not suggest the amount of
antibody or the degree of hemolysis. (However, pairing these results with the reticulocyte
count can provide some idea of the severity of the process.) This test, although reliable, does
not have 100% sensitivity. Because false-negative results do occur, repeating a test with an
initial negative result is not unreasonable if the clinical course supports an ongoing hemolytic
process.
• Complete blood cell count: A CBC with manual differential should always be included in the
evaluation of a jaundiced newborn. Measurement of the hemoglobin and hematocrit can be
helpful to determine if ongoing hemolysis severe enough to cause anemia is present. The
peripheral smear inspection is particularly valuable because it may reveal large amounts of
nucleated RBCs, suggesting active reticulocytosis; it may show abnormally shaped RBCs in
the case of hereditary membrane defects such as spherocytosis and elliptocytosis or marked
ovalocytosis in the case of hemolytic disease of the newborn. Babies with sepsis can develop
hyperbilirubinemia, and, although not conclusive, normal total white blood cell count and
manual differential can be reassuring in a healthy-appearing baby with hyperbilirubinemia.
• Serum electrolytes: Breastfed babies are known to normally develop higher levels of serum
bilirubin than their formula-fed counterparts. However, with the trend toward earlier discharge,
most breastfed babies are being discharged home before breastfeeding is well established,
and a concomitant increase has occurred in the number of babies admitted in the first week of
life with hypernatremic dehydration. Many of these babies are also significantly
hyperbilirubinemic, and the resurgence of kernicterus from its previous virtual obsolescence is
being attributed partly to this situation. Therefore, assessing serum sodium, potassium,
chloride, bicarbonate, BUN, and creatinine levels is essential; initiate treatment as appropriate
• Lumbar puncture: In the initial evaluation of hyperbilirubinemia, sepsis may be included in the
differential diagnosis. If so, collection of spinal fluid for culture and cell count is essential to
rule out meningitis. If the baby is having neurologic symptoms, cerebral spinal fluid (CSF)
evaluation is imperative; depending on the baby's symptoms, expanding the evaluation
beyond the normal aerobic bacterial culture may be prudent. If, on the other hand, the baby is
vigorous and well-appearing with isolated hyperbilirubinemia as the only symptom, a spinal
tap may not be necessary.
Imaging Studies:
• In the acute phase of bilirubin encephalopathy, neuroimaging has no major diagnostic benefit.
However, it can help rule out other diagnoses, particularly in the absence of profound
hyperbilirubinemia.
• Head ultrasonography (HUS): This modality is particularly well suited to the neonate because
it is painless, portable, and noninvasive; also, the neonatal brain is easily imaged through the
fontanelles. Sonographic imaging is not helpful in diagnosing acute bacterial encephalopathy;
however, other entities, such as intraventricular hemorrhage or parenchymal abnormalities,
can be ruled out.
• CT scanning: Computed tomography scanning has little place in the evaluation of the neonatal
brain. It is difficult to perform because the baby must be transported to the radiology