Page 236 - Clinical Hematology Atlas

220 SECTION FIVE MISCELLANEOUS

n the healthy, full-term newborn, peripheral blood collected within the first 12 hours
Iof birth has distinctive morphology. Some morphological changes persist for up to 3 to
5 days after birth. These changes should be recognized as physiological and not pathological.
For a fuller discussion of hematology in the newborn, refer to a hematology textbook such
as Hematology: Clinical Principles and Applications* or a pediatric hematology text such as
Nathan and Oski’s Hematology of Infancy and Childhood. †
Entire books have been written to address abnormal hematology in neonates and espe-
cially in the premature infant. This chapter does not attempt to address those disorders but
rather depicts morphological changes commonly seen in the healthy newborn.
Erythrocyte morphology demonstrates macrocytes, with a mean cell volume of 110 6
15 fL, which declines dramatically after the first 12 hours. Up to 3 to 10 orthochromic
normoblasts (nucleated red blood cells) may be seen per 100 white blood cells and should
disappear by day 5. Polychromasia reflects the erythropoietic activity of the newborn.
Anisocytosis is reflected in the red blood cell distribution width index, which ranges from
15.2% to 18.0%.
Occasional spherocytes are common, varying from one every two fields to one or more
in every field.
Newborn total leukocyte counts are higher than for adults, and newborns have more
segmented and band neutrophils than at any other time in childhood. An occasional meta-
‡
myelocyte may be seen without evidence of infection. Monocyte morphology is similar to
that of the adult.
Lymphocyte morphology is pleomorphic, spanning the range from reactive to mature.
The presence of a nucleolus is not uncommon; however, the chromatin pattern is coarse and
not as fine as seen in blasts. Hematogones (immature B cells) are occasionally seen in bone
marrow and peripheral blood of newborns. Caution must be exercised to correctly differ-
entiate hematogones from blasts that may indicate a pathologic condition.

* Rodak BF, Fritsma GA, Keohane EM, editors: Hematology: clinical principles and applications, ed 4,
St. Louis, 2012, Saunders.
† Orkin SH, Nathan DG, Ginsburg D et al: Nathan and Oski’s hematology of infancy and childhood, ed 7,
St. Louis, 2009, Saunders.
‡ Quinn CT, Buchanan GR: Hematopoiesis and hematologic diseases. In McMillan JA, Feigin RD,
DeAngelis C, Jones MD, editors: Oski’s pediatrics, Philadelphia, 2006, Lippincott Williams & Wilkins.