Book of Medical Disorders in Pregnancy - Tintash

anti Rh-O; the direct antiglobulin test on
the baby appears to be negative, in such
a situation it should be established that
the maternal serum contains only anti
Rh-O and, if this is found to be the case,
one must assume that the child is Rh
positive. The maternal antibody acts as a
physical barrier or block between the
antigen sites and the anti Rh O reagent
used in testing.
Rh typing of an infant who has received
intrauterine transfusion for Rh (0) hemolytic
disease may also be misleading.
The baby may appear to be Rh negative
at birth since transfused Rh negative
blood survives and the production of the
baby's Rh positive cells, is often suppressed.
A positive direct antiglobulin test does
not indicate the severity of the disease
process. Hemoglobin and indirect bilirubin
levels are better reflectors of the extent
of red cell destruction and elimination.
Cord hemoglobin:
Cord hemoglobin value below 14
gm/100 ml, is considered abnormal and
suggestive of a hemolytic process.
Severely affected infants may have cord
hemoglobin levels as low as 3 or 4 gm/lo
ml.
Serum bilirubin level in normal full-term
infants seldom exceeds 13 mg/lo ml, at
48 hours of age but premature babies
with physiological jaundice may have
serum bilirubin as high as 30 mg/l00 ml.
By the third or fourth day the liver of the
full term infant produces sufficient
glucuronyl transferase to convert bilirubin
to its excreta ble form; bilirubin
glucuronide.
Tests for assessment of disease
process:
130
Serial hemoglobin determinations -
There is hardly any great change in
hemoglobin concentration in severe
hemolytic disease in the critical first two
days of life. Actually, the hemoglobin
level may not only fall during the first
two days of life, but also remain high
these infants are in special danger of
developing kernicterus. To wait for falling
hemoglobin as an indication for
exchange transfusion in hemolytic disease
may be dangerous. Comb’s Test It
is only a diagnostic test. Many infants
with a positive Coombs test do not require
exchange transfusion. On the other
hand, some with a negative Comb’s Test
(as, for example, cases of erythroblastosis
due to ABO incompatibility) do
require transfusion to prevent kernicterus.
Therefore this test should never be
the sole criteria for exchange transfusion.
After birth:
An antibody causes destruction of the
red cells and cause. Anaemia which can
in turn cause heart failure. When build
up of bilirubin is controlled ar treated by
either photo therapy or ex-change
transfusion. Kernicterus can oc-cur and
result is severe retar-dation.
Bilirubin has been postulated to cause
neurotoxicity via 4 distinct mechanisms:
Clinical signs of bilirubin
encephalopathy typically evolve in 3
phases. Phase 1 is marked by poor suck,
hypotonic and depressed sensorium.
Fever and Hypertonia are observed in
phase. Phase 3 is characterized by high-
pitched cry hearing and visual abnormalities,
poor feeding.