Anemia of Prematurity - Portal Neonatal

Lab Studies:
WORKUP Section 5 of 10
• Diagnostic studies may be considered best by temporal grouping (ie, fetal, maternal, placental,
neonatal, postmortem). Assessments generally proceed from low-risk noninvasive tests to
higher-risk invasive techniques as required for precise and complete diagnosis to properly
manage the individual pregnancy.
• Obtain several maternal laboratory studies concurrent with the initial fetal imaging
assessment.
o Assessment of maternal blood type (red cells) and antibody screen (identification, and
quantitation when indicated, of maternal plasma antibodies) are standard screening tests
recommended in most guidelines for prenatal care. Over the past few years, the
introduction of new molecular genetic techniques (PCR) has demonstrated considerable
promise; however, definitive comparisons with standard methods are not yet available.
More than 85% of Rh-sensitized women whose anti-D titers were 1:512 or higher were
found to be HLA type DQBI allele*0201. Although this single study suggests that HLA
typing may be of value in the prospective management of isoimmunization, this
observation requires confirmation and further study.
o Qualitative and quantitative estimates of the proportion of red cells containing fetal
hemoglobin in the maternal circulation are of particular value.
� The Betke-Kleihauer technique depends on the different vulnerability of cells
containing fetal hemoglobin from those with adult hemoglobin when subjected to acidelution.
� A newer method using flow cytometry has also been found to be useful.
� Results using either method must be interpreted with considerable caution, since poor
sensitivity and specificity of these diagnostic tests has been demonstrated in several
studies.
o The search for maternal-fetal infection must be intensive. Syphilis serology was a standard
prenatal screening test for decades. More recently, the test has been used more
selectively, despite the absence of any good evidence for this change. If fetal hydrops is
suspected, syphilis serology is mandatory with repeat serial testing and, very importantly,
with dilution of maternal serum. The prozone effect has been demonstrated repeatedly
with fetal hydrops due to syphilis, thus dilution of maternal serum to avoid false-negative
results is required.
o Antibody screens for common fetal infections (toxoplasmosis, other infections, rubella,
CMV infection, and herpes simplex [TORCH]) and more sensitive and specific enzymelinked
immunosorbent assay (ELISA) studies for individual infectious agents have been
used for many years. More recently, the PCR technique generally is accepted as the
criterion standard and should be employed whenever possible.
o Hemoglobin electrophoresis for alpha-thalassemia heterozygosity has been useful in
ethnically at-risk populations. In regions where ethnic diversity is high, routine screening
may be preferable to selection based on ethnicity. More recently, PCR screens and
colorimetric monoclonal antizeta antibody tests for heterozygote alpha-thalassemia have
been demonstrated as economically feasible screening procedures.
o Maternal serum screening tests (multiple-marker, triple-screen, triple-marker), commonly
used if fetal anomaly is suspected, are of uncertain value with fetal hydrops.
� In one study, positive screening tests (any of the 3 used) with a sensitivity of only 60%
in 19 cases of Turner syndrome distinguished some fetuses with cystic hygroma
and/or hydrops from those without. Individual components of these tests were
examined separately in several other studies.
� Elevated AFP levels have been reported in hydrops associated with fetomaternal
hemorrhage, umbilical cord hemangioma, polycystic kidneys, CMV, and Parvovirus;