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Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
1
HEMOLYTIC DISEASE OF THE NEWBORN: A REVIEW
Obeagu Emmanuel Ifeanyi
Diagnostic Laboratory Unit, University Health Services, Michael Okpara University of Agriculture,
Umudike, Abia State, Nigeria.
INTRODUCTION
Although the Rh antibody was and still is the
most common cause of severe hemolytic disease of the
newborn, other alloimmune antibodies belonging to Kell
(K and k), Duffy (Fya), Kidd (Jka and Jkb), and MNSs
(M, N, S, and s) systems do cause severe hemolytic
disease of the newborn [1].
Frequency of Rh negativity is higher in whites
(15%) than in blacks (5%) and Hispanics (8%) and is rare
in Eskimos, Native Americans, Japanese and Asians,
especially in Chinese individuals. The paternal
heterozygosity determines the likelihood of an Rh-
positive child being born to an Rh-negative mother.
Pathophysiology The exposure of the Rh-
negative mother to Rh-positive red cells occurs as a result
of asymptomatic fetomaternal hemorrhage during
pregnancy. The Kleihauer-Betke acid elution technique
that determines the proportion of fetal RBCs in maternal
circulation has shown the incidence of fetomaternal
hemorrhage to be 75% of all pregnancies. Incidence and
degree of such hemorrhage appears to increase with
gestation. Fetomaternal hemorrhage has been documented
in 7%, 16%, and 29% of mothers during their first, second
and third trimesters, respectively. Risk is also increased in
pregnancies complicated by placental abruption,
spontaneous or therapeutic abortion, and toxemia, as well
as after cesarean delivery and ectopic pregnancy.
Procedures such as amniocentesis, chorionic
villus sampling, and cordocentesis also increase the risk
of alloimmunization. Because the transplacental
hemorrhage is less than 0.1 mL in most pregnancies, most
women are sensitized as a result of small, undetectable
fetomaternal hemorrhage.
Corresponding Author:- Obeagu Emmanuel Ifeanyi E mail: emmanuelobeagu@yahoo.com
International Journal of Pharmacotherapy
www.ijopjournal.com ISSN 2249 - 7765
Print ISSN 2249 - 7773
ABSTRACT
Haemolytic disease of the newborn (HDN) is a condition in which the lifespan of the fetal/neonatal red cells is
shortened due to maternal alloantibodies against red cell antigens inherited from the father. Maternal IgG can cross the
placenta, thus IgG red cell alloantibodies can gain access to the fetus. If the fetal red cells contain the corresponding
antigen then binding of antibody to red cells will occur. When the antibody is of clinical significance (e.g. anti-D, -c, -E, -
K, -Jka), and of sufficient potency, the coated cells will be prematurely removed by the fetal mononuclear phagocytic
system. The effects on the fetus/newborn infant may vary according to the characteristics of the maternal alloantibody.
The antibodies giving rise to HDN most commonly belong to the Rh or ABO blood group systems. The morbidity of Rh
HDN is explained by the great immunogenicity of the D antigen; HDN due to anti-c is also important and its incidence
comes second amongst the cases of severe HDN closely followed by the non-Rh antibody, anti-K. (The anaemia caused
by anti-K is more properly called alloimmune anaemia of the fetus and newborn as it is due to direct inhibition of
erythropoiesis by the antibody and haemolysis is not a feature.) Antibodies against antigens in almost all the blood group
systems (e.g. Duffy, Kidd, etc.) and against the so-called ‘public’ and ‘private’ antigens, have also been responsible for
HDN. However, IgM cannot cross the placenta and Lewis and P1 antibodies, which occur frequently during pregnancy,
are usually IgM and do not lead to HDN. Furthermore, the Lewis antigens are not fully developed at birth
.
Key words: Haemolytic disease of the newborn, Epidemiology, History.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
2
After the initial exposure to a foreign antigen, B-
lymphocyte clones that recognize the RBC antigen are
established. The maternal immune system initially
produces antibodies of the immunoglobulin M (IgM)
isotype that do not cross the placenta and later produces
antibodies of the IgG isotype that traverse the placental
barrier. Predominant antibody subclass appears to be
IgG1 in one third of individuals whereas a combination of
IgG1 and IgG3 subclasses are found in the remaining
individuals.
IgG3 is more efficient in binding to
reticuloendothelial cells and causing hemolysis because of
its longer hinge region. This is termed the primary
response and is dose dependent (documented in 15% of
pregnancies with 1 mL of Rh-positive cells in an Rh-
negative individual compared with 70% of pregnancies
after 250 mL). A repeat exposure to the same antigen
rapidly induces the production of IgG. This secondary
immune response can be induced with as little as 0.03 mL
of Rh-positive RBCs.
The risk of Rh immunization after the delivery of
the first child to a nulliparous Rh-negative mother is 16%
if the Rh-positive fetus is ABO compatible with its
mother, 2% if the fetus is ABO incompatible, and 2-5%
after an abortion. The ABO-incompatible RBCs are
rapidly destroyed in the maternal circulation, reducing the
likelihood of exposure to the immune system. The degree
of Rh sensitization of the mother is directly related to the
amount of fetomaternal hemorrhage (ie, 3% with < 0.1
mL compared with 22% with >0.1 mL).
After sensitization, maternal anti-D antibodies
cross the placenta into fetal circulation and attach to Rh
antigen on fetal RBCs, which form rosettes on
macrophages in the reticuloendothelial system, especially
in the spleen. These antibody-coated RBCs are lysed by
lysosomal enzymes released by macrophages and natural
killer lymphocytes and are independent of the activation
of the complement system.
Reticulocytosis is noted when fetal Hb deficit
exceeds 2 gm/dl compared with gestational age norms.
Tissue hypoxia develops as fetal anemia becomes severe.
When the hemoglobin (Hb) level drops below 8 g/dL, a
rise in umbilical arterial lactate occurs. When the Hb level
drops below 4g/dL, increased venous lactate is noted.
Hydrops fetalis occurs when fetal Hb deficit exceeds 7
g/dL and starts as fetal ascites and evolves into pleural
effusions and generalized edema. The various
mechanisms responsible for hydrops are
hypoalbuminemia secondary to depressed liver function,
increased capillary permeability, iron overload secondary
to hemolysis, and increased venous pressures due to poor
cardiac function [2].
Prolonged hemolysis leads to severe anemia,
which stimulates fetal erythropoiesis in the liver, spleen,
bone marrow, and extramedullary sites, such as the skin
and placenta. In severe cases, this can lead to
displacement and destruction of hepatic parenchyma by
erythroid cells, resulting in dysfunction and
hypoproteinemia. Destruction of RBCs releases heme that
is converted to unconjugated bilirubin.
Hyperbilirubinemia becomes apparent only in the
delivered newborn because the placenta effectively
metabolizes bilirubin. Hemolytic disease of the newborn
due to Kell sensitization results in hemolysis and
suppression of erythropoiesis because the Kell antigen is
expressed on the surface of erythroid progenitors. This
leads to severe fetal disease at a lower maternal antibody
titer than in Rhesus disease.
Hemolysis associated with ABO incompatibility
exclusively occurs in type-O mothers with fetuses who
have type A or type B blood, although it has rarely been
documented in type-A mothers with type-B infants with a
high titer of anti-B IgG. In mothers with type A or type B,
naturally occurring antibodies are of the IgM class and do
not cross the placenta, whereas 1% of type-O mothers
have a high titer of the antibodies of IgG class against
both A and B. They cross the placenta and cause
hemolysis in fetus.
Hemolysis due to anti-A is more common than
hemolysis due to anti-B, and affected neonates usually
have positive direct Coombs test results. However,
hemolysis due to anti-B IgG can be severe and can lead to
exchange transfusion. Because A and B antigens are
widely expressed in various tissues besides RBCs, only a
small portion of antibodies crossing the placenta are
available to bind to fetal RBCs. Recent analysis of IgG
subclass in ABO incompatible direct coombs positive
neonates showed IgG2 was predominent antibody which
is poorly transferred across placenta and less efficient in
causing hemolysis while IgG1 was noted in 22% of
neonates and as a group had similar rate of hemolysis and
severity of hyperbilirubinemia [3].
In addition, fetal RBCs appear to have less
surface expression of A or B antigen, resulting in few
reactive sites; hence the low incidence of significant
hemolysis in affected neonates. This results in
hyperbilirubinemia as a predominant manifestation of
incompatibility (rather than anemia), and peripheral blood
film frequently reveals a large number of spherocytes and
few erythroblasts, unlike what is seen in Rh
incompatibility (erythroblastosis fetalis), in which blood
film reveals a large number of nucleated RBCs and few
spherocytes [4].
Epidemiology
Frequency: United States
Before the establishment of modern therapy, 1%
of all pregnant women developed Rh alloimmunization.
Since the advent of routine prophylaxis of at-risk women,
incidence of Rh sensitization has declined from 45 cases
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
3
per 10,000 births to 10.2 cases per 10,000 total births,
with less than 10% requiring intrauterine transfusion.
Alloimmunization due to Kell antigen accounts for 10%
of severely affected fetuses. The most recent data from
review of 2001 birth certificates in the United States by
the Centers for Disease Control and Prevention (CDC)
indicates that Rh sensitization affects 6.7 newborns per
1000 live births [5].
Currently, anti-D is still one of the most common
antibodies found in pregnant women, followed by anti-K,
anti-c, and anti-E. Of those fetuses who require
intrauterine transfusions, 85%, 10%, and 3.5% were due
to anti-D, anti-K, and anti-c, respectively [6]. ABO
incompatibility frequently occurs during the first
pregnancy and is present in approximately 12% of
pregnancies, with evidence of fetal sensitization in 3% of
live births. Less than 1% of births are associated with
significant hemolysis.
Mortality/Morbidity
Almost 50 different red cell surface antigens
have been found to be responsible for hemolytic disease
of fetus and newborn. Only 3 antibodies are associated
with severe fetal disease: anti-RhD, anti-Rhc, and anti-
Kell (K1). Nearly 50% of the affected newborns do not
require treatment, have mild anemia and
hyperbilirubinemia at birth, and survive and develop
normally. Approximately 25% are born near term but
become extremely jaundiced without treatment and either
die (90%) or become severely affected by kernicterus
(10%). The remaining 25% of affected newborns are
severely affected in utero and become hydropic; about
half of newborns are affected before 34 weeks' gestation,
and the other half are affected between 34 weeks'
gestation and term [7].
Exchange Transfusion
A study by Smits-Wintjens et al indicated that
exchange transfusion in neonates increases the risk of
sepsis, severe thrombocytopenia, leukocytopenia,
hypernatremia, and hypocalcemia in neonates with
hemolytic disease of the newborn (HDN) [8].
Race Incompatibility involving Rh antigens (anti-D or
anti-c) occurs in about 10% of all pregnancies among
whites and blacks; in contrast, it is very rare in Asian
women.
Sex Fetal sex plays a significant role in the degree of
response to maternal antibodies. An apparent 13-fold
increase is observed in fetal hydrops in RhD-positive
male fetuses compared with female fetuses in similarly
sensitized pregnancies [9].
History Two usual patterns of Rh isoimmunization
severity are noted. The disease may remain at the same
degree of severity or may become progressively worst
with each pregnancy. A history of hydropic birth
increases the risk of fetal hydrops in the next pregnancy to
90%; the fetal hydrops occurs at about the same time or
earlier in gestation in the subsequent pregnancy. Women
at risk for alloimmunization should undergo an indirect
Coombs test and antibody titers at their first prenatal visit.
If results are positive, obtain a paternal blood type and
genotype with serologic testing for other Rh antigens (C,
c, E, e). Obtaining serial maternal titers is suggested if
the father is homozygous. If the father is heterozygous,
determine fetal Rh genotype using PCR for the RHD gene
on fetal cells obtained at amniocentesis [10] or on cell-
free DNA in maternal circulation [11]. The sensitivity and
specificity of PCR typing on amniotic fluid is 98.7% and
100%, respectively. However, obtaining maternal blood
to rule out a maternal RHD pseudogene (in a Rh-positive
fetus) and obtaining paternal blood to rule out RHD gene
locus rearrangement (in a Rh-negative fetus) is important
to improve the accuracy. Determining fetal Rh genotype is
also possible by performing cordocentesis, which is also
called fetal blood sampling (FBS). FBS is associated with
a more than 4-fold increase in perinatal loss compared
with amniocentesis.
Indicators for severe hemolytic disease of the
newborn (HDN) include mothers who have had previous
children with hemolytic disease, rising maternal antibody
titers, rising amniotic fluid bilirubin concentration, and
ultrasonographic evidence of fetal hydrops (eg, ascites,
edema, pleural and pericardial effusions, decreasing
hemoglobin [Hb] levels).
Physical
An infant born to an alloimmunized mother
shows clinical signs based on the severity of the disease.
The typical diagnostic findings are jaundice, pallor,
hepatosplenomegaly, and fetal hydrops in severe cases.
The jaundice typically manifests at birth or in the first 24
hours after birth with rapidly rising unconjugated
bilirubin level. Occasionally, conjugated
hyperbilirubinemia is present because of placental or
hepatic dysfunction in those infants with severe hemolytic
disease. Anemia is most often due to destruction of
antibody-coated RBCs by the reticuloendothelial system,
and, in some infants, anemia is due to intravascular
destruction. The suppression of erythropoiesis by
intravascular transfusion (IVT) of adult Hb to an anemic
fetus can also cause anemia. Extramedullary
hematopoiesis can lead to hepatosplenomegaly, portal
hypertension, and ascites.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
4
Anemia is not the only cause of hydrops.
Excessive hepatic extramedullary hematopoiesis causes
portal and umbilical venous obstruction and diminished
placental perfusion because of edema. Increased placental
weight and edema of chorionic villi interfere with
placental transport. Fetal hydrops results from fetal
hypoxia, anemia, congestive cardiac failure, and
hypoproteinemia secondary to hepatic dysfunction.
Commonly, hydrops is not observed until the Hb level
drops below approximately 4 g/dL (Hct < 15%) .
Clinically significant jaundice occurs in as many as 20%
of ABO-incompatible infants.
Causes In the absence of a positive direct Coombs test
result, other causes of pathologic jaundice svhould be
considered, including intrauterine congenital infections;
erythrocyte membrane defects (eg, hereditary
spherocytosis, hereditary elliptocytosis, hereditary
pyropoikilocytosis); RBC enzyme deficiencies (eg,
glucose-6-phosphate dehydrogenase [G6PD] deficiency,
pyruvate kinase deficiency, triosephosphate isomerase
deficiency); and nonhemolytic causes (eg, enclosed
hemorrhages, hypothyroidism, GI obstruction, and
metabolic diseases).
Similarly, hydrops can occur from nonimmune
hematologic disorders that cause anemia, such as
hemoglobinopathies (eg, α-thalassemia major), cardiac
failure due to dysrhythmia, congenital heart defects, and
infections (eg, syphilis, cytomegalovirus [CMV],
parvovirus).
Common causes of hemolytic disease of the newborn
o Rh system antibodies
o ABO system antibodies
Uncommon causes - Kell system antibodies
Rare causes
o Duffy system antibodies
o MNS and s system antibodies
No occurrence in hemolytic disease of the newborn
o Lewis system antibodies
o P system antibodies
Differential Diagnoses
Anemia, Acute
Atrial Flutter
Cardiac Tumors
Cytomegalovirus Infection
Galactose-1-Phosphate Uridyltransferase Deficiency
(Galactosemia)
Hydrops Fetalis
Hypothyroidism
Parvovirus B19 Infection
Syphilis
Toxoplasmosis
Tyrosinemia
Laboratory Studies
The following findings may be noted in hemolytic
disease of the newborn (HDN):
Hemolytic disease of the newborn is characterized by
one or more of the following clinical presentations:
Rapidly progressive severe hyperbilirubinemia or
prolonged hyperbilirubinemia
Positive maternal antenatal antibody findings and/or
diagnosis of anemia or fetal hydrops
Positive neonatal direct Coombs test (direct
antiglobulin test)
Hemolysis on blood film findings
The severity of hematologic abnormalities is directly
proportional to the severity of hemolysis and the extent of
hematopoiesis. The following abnormalities are observed
on CBC count findings:
Anemia: Measurements are more accurate using
central venous or arterial samples rather than capillary
blood.
Increased nucleated RBCs, reticulocytosis,
polychromasia, anisocytosis, spherocytes, and cell
fragmentation
o The reticulocyte count can be as high as 40% in
patients without intrauterine intervention.
o The nucleated RBC count is elevated and falsely
elevates the leukocyte count, reflecting a state of
erythropoiesis.
o Spherocytes (< 40%) are more commonly observed
in cases of ABO incompatibility. Glucose does not correct
the autohemolysis in ABO incompatibility unlike
hereditary spherocytosis.
o In severe hemolytic disease, schistocytes and burr
cells may be observed, reflecting ongoing disseminated
intravascular coagulation.
o A low reticulocyte count is observed in fetuses
provided with intravascular transfusion in utero and with
Kell alloimmunization.
o Abnormally elevated mean cell hemoglobin
concentration (MCHC) and red cell distribution width
(RDW) values should prompt a diagnosis of hereditary
spherocytosis.
Neutropenia: This condition seems to be secondary to
stimulation of erythropoiesis in favor of myelopoiesis.
However, neutrophilia can be observed after intrauterine
transfusion because of an increase in circulating cytokines
(granulocyte-macrophage colony-stimulating factor).
Thrombocytopenia: This condition is common,
especially after intrauterine or exchange transfusions
because of platelet-poor blood product and suppression of
platelet production in favor of erythropoiesis.
Hypoglycemia is common and is due to islet cell
hyperplasia and hyperinsulinism. The abnormality is
thought to be secondary to release of metabolic
byproducts such as glutathione from lysed RBCs.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
5
Hypokalemia, hyperkalemia, and hypocalcemia are
commonly observed during and after exchange
transfusion.
Serologic test findings include the following:
Indirect Coombs test and direct antibody test results
are positive in the mother and affected newborn. Unlike
Rh alloimmunization, direct antibody test results are
positive in only 20-40% of infants with ABO
incompatibility. In a recent study, positive direct antibody
test findings have a positive predictive value of only 23%
and a sensitivity of only 86% in predicting significant
hemolysis and need for phototherapy, unless the findings
are strongly positive (4+). This is because fetal RBCs
have less surface expression of type-specific antigen
compared with adult cells. A prospective study has shown
that the titers of maternal immunoglobulin G (IgG) anti-A
or anti-B may be more helpful in predicting severe
hemolysis and hyperbilirubinemia. The sensitivity and
specificity of IgG titers of 512 or higher in predicting
need for invasive intervention was 90% and 73%,
respectively.
Although the indirect Coombs test result (neonate's
serum with adult A or B RBCs) is more commonly
positive in neonates with ABO incompatibility, it also has
poor predictive value for hemolysis. This is because of the
differences in binding of IgG subtypes to the Fc receptor
of phagocytic cells and, in turn, in their ability to cause
hemolysis.
IgG2 is more commonly found in maternal serum but
has weak lytic activity, which leads to the observation of
little or no hemolysis with a positive direct antibody test
result. On the other hand, significant hemolysis is
associated with a negative direct antibody test result when
IgG1 and IgG3 are predominant antibodies, which are in
low concentration but have strong lytic activity, crossing
to neonatal circulation.
In newborns with hemolytic disease due to anti-c or
anti-C antibodies, direct antibody test results may be
negative, and the diagnosis is established after indirect
Coombs testing.
Imaging Studies
High-resolution ultrasonography has been a
major advance in detection of early hydrops and has also
reduced the fetal trauma and morbidity rate to less than
2% during percutaneous umbilical blood sampling
(PUBS) and placental trauma during amniocentesis. High-
resolution ultrasonography has been extremely helpful in
directing the needle with intraperitoneal transfusion (IPT)
and intravascular transfusion (IVT) in fetal location.
Medical Care
Management of Maternal Alloimmunization
As a rule, serial maternal antibody titers are
monitored until a critical titer of 1:32, which indicates that
a high risk of fetal hydrops has been reached. At this
point, the fetus requires very intense monitoring for signs
of anemia and fetal hydrops. In Kell alloimmunization,
hydrops can occur at low maternal titers because of
suppressed erythropoiesis, and, thus, a titer of 1:8 has
been suggested as critical. Maternal titers are not useful in
predicting the onset of fetal anemia after the first affected
gestation. Large differences in titer can be seen in the
same patient between different laboratories, and a newer
gel technique produces higher titer results than the older
tube method. Therefore, standard tube methodology
should be used to determine critical titer, and a change of
more than 1 dilution represents a true increase in maternal
antibody titer. For all the antibodies responsible for
hemolytic disease of the newborn (HDN), a 4-fold
increase in any antibody titer is typically considered a
significant change that requires fetal evaluation.
When indicated, amniocentesis can be performed
as early as 15 weeks' gestation (rarely needed in first
affected pregnancy before 24 weeks' gestation) to
determine fetal genotype and to assess the severity.
Maternal and paternal blood samples should be sent to the
reference laboratory with amniotic fluid sample to
eliminate false-positive results (from maternal
pseudogene or Ccde gene) and false-negative results
(from a rearrangement at the RHD gene locus in the
father). Fetal Rh-genotype determination in maternal
plasma has become routine in many European countries
and is being offered in the United States. Fetal cell-free
DNA accounts for 3% of total circulating maternal plasma
DNA, is found as early as 38 days of gestation, and is
derived from apoptosis of the placental cytotrophoblast
layer. It is subjected to real-time PCR for the presence of
RHD gene–specific sequences and has been found to be
accurate in 99.5% of cases. The SRY gene (in the male
fetus) and DNA polymorphisms in the general population
(in the female fetus) are used as internal controls to
confirm the fetal origin of the cell-free DNA.A panel of
92 SNPs is compared between maternal sample from
buffy coat and plasma. A difference of more than 6 single
nucleotide polymorphisms confirms presence of fetal
DNA and the validity of the test in a female fetus.
Unfortunately, cell-free fetal DNA testing for
determining the genotype for other red blood cell antigens
such as E and Kell is not yet available in United States.
Serial amniocentesis is begun at 10-14 day
intervals to monitor the severity of the disease in the
fetus. All attempts should be made to avoid transplacental
passage of needle which can lead to fetomaternal
hemorrhage (FMH) and a further rise in antibody titer.
Early ultrasonography is performed to establish correct
gestational age. Frequent ultrasonographic monitoring is
also performed to assess fetal well-being and to detect
moderate anemia and early signs of hydrops.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
6
During the period when intrauterine peritoneal
transfusion was the only means of treatment, newborns
were routinely delivered at 32 weeks' gestation. This
approach resulted in a high incidence of hyaline
membrane disease and exchange transfusions. With the
advent of intravascular transfusion (IVT) in utero, the
general approach to the severely affected fetus is to
perform IVT as required until 35 weeks' gestation, with
delivery planned at term. Establishment of lung maturity
is difficult in these fetuses because of contamination of
amniotic fluid with residual blood during transfusion;
however, if delivery is planned prior to 34 weeks'
gestation, maternal steroid administration to enhance fetal
lung maturity is indicated.
Recently washed maternal RBCs have been
successfully used as a source of antigen-negative RBCs in
the event of rare incompatibility but also have been
routinely used because of benefits such as decreased risk
for sensitization to new red cell antigens, a longer
circulating half-life being fresh and decreased risk of
transmission of viral agents. Mother can donate a unit of
red cells after the first trimester.
Extensive plasmapheresis with partial replacement using
5% albumin and intravenous immunoglobulin (IVIG) or
the administration of IVIG at 1 g/kg body weight weekly
has been shown to be moderately effective. The
mechanism of action appears to be blockage of Fc
receptors in the placenta, reducing antibody transport
across to the fetus, Fc receptors on the phagocytes in the
fetal reticuloendothelial system, and feedback inhibition
of maternal antibody synthesis.
Similar regimens of tests and treatment are used
in the management of pregnancies affected by nonRhD
alloimmunization, such as anti-Rhc, anti-K (K1), and anti-
M. Once the mother is diagnosed with an antibody
associated with hemolytic disease, an indirect Coombs
titer is performed, along with paternal testing for involved
antigen and zygosity. Maternal titers are repeated
(monthly until 28 weeks' gestation and then every 2 wk)
until a threshold for fetal anemia is reached (1:8 for Kell
and 1:32 for rest).
Management of the sensitized neonate
Mild hemolytic disease accounts for 50% of
newborns with positive direct antibody test results. Most
of these newborns are not anemic (cord hemoglobin [Hb]
>14 g/dL) and have minimal hemolysis (cord bilirubin < 4
mg/dL). Apart from early phototherapy, they require no
transfusions. However, these newborns are at risk of
developing severe late anemia by 3-6 weeks of life.
Therefore, monitoring their Hb levels after hospital
discharge is important.
Moderate hemolytic disease accounts for
approximately 25% of affected neonates. Moderate
hemolytic disease of newborn is characterized by
moderate anemia and increased cord bilirubin levels.
These infants are not clinically jaundiced at birth but
rapidly develop unconjugated hyperbilirubinemia in the
first 24 hours of life. Peripheral smear shows numerous
nucleated RBCs, decreased platelets, and, occasionally, a
large number of immature granulocytes. These newborns
often have hepatosplenomegaly and are at risk of
developing bilirubin encephalopathy without adequate
treatment. Early exchange transfusion with type-O Rh-
negative fresh RBCs with intensive phototherapy is
usually required. Use of IVIG in doses of 0.5-1 g/kg in a
single or multiple dose regimen have been able to
effectively reduce need for exchange transfusion [12].
Severe hemolytic disease accounts for the
remaining 25% of the alloimmunized newborns who are
either stillborn or hydropic at birth. The fetal hydrops is
predominantly caused by a capillary leak syndrome due to
tissue hypoxia, hypoalbuminemia secondary to hepatic
dysfunction, and high-output cardiac failure from anemia.
About half of these fetuses become hydropic before 34
weeks' gestation and need intensive monitoring and
management of alloimmunized gestation as described
earlier. Mild hydrops involving ascites reverses with IVTs
in only 88% of cases with improved survival but severe
hydrops causing scalp edema and severe ascites and
pleural effusions reverse in 39% of cases and are
associated with poor survival.
Management of ABO Incompatibility
Management of hyperbilirubinemia is a major
concern in newborns with ABO incompatibility. The
criteria for exchange transfusion and phototherapy are
similar to those used in Rh alloimmunization. IVIG has
also been very effective when administered early in the
course. Tin (Sn) porphyrin a potent inhibitor of heme
oxygenase, the enzyme that catalyzes the rate-limiting
step in the production of bilirubin from heme, has been
shown to reduce the production of bilirubin and reduce
the need for exchange transfusion and the duration of
phototherapy in neonates with ABO incompatibility.
Tin or zinc protoporphyrin or mesoporphyrins
have been studied in newborns. They must be
administered intramuscularly in a dose based on body
weight, and their effectiveness appears to be dose related
in all gestations.Their possible toxic effects include skin
photosensitization, iron deficiency, and possible
inhibition of carbon monoxide production. Their use in
Rh hemolytic disease of newborn has not been reported.
Their routine use cannot be recommended yet because of
lack of long-term safety data.
Further Inpatient Care
The following may be indicated in patients with
hemolytic disease of newborn (HDN):
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
7
The stabilization of a hydropic newborn requires a
high level of intensive coordinated management by a
neonatal team well prepared for the possibly affected
infant.
In general, immediate intubation followed by
draining of pleural effusions and ascites results in
immediate improvement in respiratory gas exchange.
A cautious correction of anemia with packed RBCs
or by exchange transfusion is necessary to prevent
circulatory overload.
These neonates have normal blood volume but
elevated central venous pressure.
A close monitoring of metabolic status (eg, watching
for hypoglycemia, hypocalcemia, hyperkalemia, acidosis,
hyponatremia, renal failure) is absolutely essential to
achieve a successful outcome.
Despite of the first use of phototherapy by Cremer
and associates more than 40 years ago, no standard
method for delivering phototherapy is yet available.
Exchange transfusion removes circulating bilirubin
and antibody-coated RBCs, replacing them with RBCs
compatible with maternal serum and providing albumin
with new bilirubin binding sites. The process is time
consuming and labor intensive but remains the ultimate
treatment to prevent kernicterus. The process involves the
placement of a catheter via the umbilical vein into the
inferior vena cava and removal and replacement of 5- to
10-mL aliquots of blood sequentially, until about twice
the volume of the neonate's circulating blood volume is
reached (ie, double-volume exchange).
This process removes approximately 70-90% of fetal
RBCs. The amount of bilirubin removed directly varies
with the pretransfusion bilirubin level and amount of
blood exchanged. Because most of the bilirubin is in the
extravascular space, only about 25% of the total bilirubin
is removed by an exchange transfusion. A rapid rebound
of serum bilirubin level is common after equilibration and
frequently requires additional exchange transfusions.
The indications for exchange transfusion are
controversial, except for the fact that severe anemia and
the presence of a rapidly worsening jaundice despite
optimal phototherapy in the first 12 hours of life indicate
the need for exchange transfusion. In addition, the
presence of conditions that increase the risk of bilirubin
encephalopathy lowers the threshold of safe bilirubin
levels.
Exchange transfusion should be considered in newborns
born at more than 38 weeks' gestation with a bilirubin-to-
albumin ratio of 7.2 and in newborns born at 35-37 weeks'
gestation with a bilirubin-to-albumin ratio of 6.8.
Exchange transfusion is not free of risk, with the
estimated morbidity rate at 5% and the mortality rate as
high as 0.5%. Apnea, bradycardia, cyanosis, vasospasm,
and hypothermia with metabolic abnormalities (eg,
hypoglycemia, hypocalcemia) are the most common
adverse effects.
IVIG has been shown to reduce the need for
exchange transfusion in hemolytic disease of the newborn
due to Rh or ABO incompatibility. The number needed to
treat to prevent one exchange transfusion was noted to be
2.7 and was estimated to be 10, if all the infants with
strongly positive direct Coombs test were to receive the
medication [13,14]. In addition, it also reduced the
duration of hospital stay and phototherapy. Although it
was very effective as a single dose, multiple doses were
more effective in stopping the ongoing hemolysis and
reducing the incidence of late anemia.
Tin-mesoporphyrin in a dose of 4.5 mg/kg (6
µmole/kg) was used in an infant with persistent hemolysis
due to Rh alloimmunization to prevent need for further
phototherapy, without any adverse effects.
Prevention
Consider the following in patients with hemolytic
disease of the newborn:
Rh immune globin (RhIG) was licensed in 1968 in
North America after several studies demonstrated its
effectiveness in preventing Rh alloimmunization when
administered to the mother within 72 hours of delivery.
The current standard is to administer RhIG to all
unsensitized Rh-negative women at 28 weeks' gestation
with an additional dose administered soon after birth if
the infant is Rh-positive, irrespective of the ABO status of
the baby. RhIG is not indicated for mothers with weak or
partial D status because most are not at risk for
alloimmunization.
The standard dose of RhIG is 300 mcg and is
increased (300 mcg for every 25 mL of fetal blood in
maternal circulation) based on the amount of fetomaternal
hemorrhage, which can be quantified using the Kleihauer-
Betke technique. Because only 50% of pregnancies with
excess fetomaternal hemorrhage can be identified by
clinical risk factors, routine screen for excess fetomaternal
hemorrhage (FMH) is undertaken in all Rh negative
women. However, if the incidence of excess FMH is
0.6%, the maximum risk of sensitization is 0.1%,
suggesting routine assessment for excess FMH may not
be justified.
Also administer RhIG to unsensitized Rh-negative
women after any event known to be associated with
transplacental hemorrhage such as spontaneous or elective
abortion, ectopic pregnancy, amniocentesis, chorionic
villous sampling, fetal blood sampling (FBS), hydatiform
mole, fetal death in late gestation, blunt abdominal
trauma, and external cephalic version. The indications for
first trimester threatened abortion and ectopic pregnancy
with no cardiac activity are not cost effective and are left
to the clinician.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
8
No more than 5 units of RhIG should be given by
intramuscular route in 24-hour period. An intravenous
preparation is now available for administration of large
doses. If RhIG was inadvertently omitted after delivery,
the protection can still be offered if given within first 4
weeks. A repeat dose is not needed if delivery occurs
within 3 weeks after administration of RhIG during
antenatal period. The current incidence of Rh
immunization stands at 0.1% with the above
recommendations.
Most RhIG is derived from human plasma obtained
from sensitized women or male donors sensitized with
RhD positive cells. Because it is a blood product, it has
risks of transmission of viral infections such as hepatitis C
and may not be acceptable in some religious
denomination. Hence 2 monoclonal anti-D antibodies
derived from recombinant technology, BRAD-1 and
BRAD-3, are being tested in clinical trials. A new novel
polyclonal recombinant antibody, rozrolimupab has also
been tested in phase I and II clinical trials with no adverse
effects.
Complications
The 2 major complications of hemolytic disease
of the newborn are bilirubin encephalopathy (kernicterus)
and late anaemia of infancy.
Bilirubin encephalopathy
o Before the advent of exchange transfusion,
kernicterus affected 15% of infants born with
erythroblastosis. Approximately 75% of these neonates
died within 1 week of life, and a small remainder died
during the first year of life. Survivors had permanent
neurologic sequelae and were thought to have accounted
for 10% of all patients with cerebral palsy (CP).
o The mechanism by which unconjugated bilirubin
enters the brain and damages it is unclear. Bilirubin enters
the brain as lipophilic free bilirubin unbound to albumin,
as supersaturated bilirubin acid that precipitates on lipid
membrane in low pH, or as a bilirubin-albumin complex
that transfers bilirubin to tissue by direct contact with
cellular surface. The blood-brain barrier is comprised of
ATP-dependent transport proteins and pumps free
bilirubin from the brain back into plasma and maintains
the concentration gradient of unconjugated bilirubin. A
damaged blood-brain barrier enhances the entry and fails
to remove all forms of bilirubin into the brain, which is
especially important in preterm neonates with respiratory
acidosis and vascular injury.
o Bilirubin has been postulated to cause neurotoxicity
via 4 distinct mechanisms [15]. (1) interruption of normal
neurotransmission (inhibits phosphorylation of enzymes
critical in release of neurotransmitters), (2) mitochondrial
dysfunction, (3) cellular and intracellular membrane
impairment (bilirubin acid affects membrane ion channels
and precipitates on phospholipid membranes of
mitochondria), and (4) interference with enzyme activity
(binds to specific bilirubin receptor sites on enzymes).
o The pathologic findings include characteristic
staining and neuronal necrosis in basal ganglia ,
hippocampal cortex , brainstem nuclei , and cerebellum .
The cerebral cortex is generally spared. About half of
these neonates also have extraneuronal lesions, such as
necrosis of renal tubular, intestinal mucosal, and
pancreatic cells.
o Clinical signs of bilirubin encephalopathy typically
evolve in 3 phases. Phase 1 is marked by poor suck,
hypotonia, and depressed sensorium. Fever and
hypertonia are observed in phase 2, and, at times, the
condition progresses to opisthotonus. Phase 3 is
characterized by high-pitched cry, hearing and visual
abnormalities, poor feeding, and athetosis.
o Long-term sequelae include choreoathetoid CP,
upward gaze palsy, sensorineural hearing loss, dental
enamel hypoplasia of the deciduous teeth, and, less often,
mental retardation. The abnormal or reduced auditory
brainstem response of wave I (auditory nerve) and wave
II and V (auditory brainstem nuclei), depicted as
decreased amplitudes, and increased interval I-III and I-V
characterize phase I of early, but reversible,
encephalopathy. Subtle bilirubin encephalopathy that
consists of either cognitive dysfunction, isolated hearing
loss, or movement disorder has been described in absence
of kernicterus and better correlates with free bilirubin
levels.
o Currently, the mortality rate stands at 50% in term
newborns, but mortality is nearly universal in the preterm
population who may simply appear ill without signs
specific for kernicterus. Research has indicated that
bilirubin production rates may be the critical piece of
information identifying jaundiced infants at risk of
neurotoxicity. A high bilirubin production rate is thought
to result in rapid transfer of bilirubin to tissue, causing
high tissue load, in which case any small further increase
has great potential to enter the brain. Because the total
serum bilirubin represents not only bilirubin production
but also distribution and elimination, it is not an absolute
indicator of risk of kernicterus. Techniques have been
developed to measure the bilirubin production
ratesaccurately and noninvasively using end-tidal carbon
monoxide measurement and percutaneous measurement
of carboxyhemoglobin.
Late anemia of infancy
o Infants with significant hemolytic disease often
develop anemia in the first month of life and frequently
(50%) require packed RBC transfusion. The anemia
appears to be due to several factors including suppression
of fetal erythropoiesis from transfusion of adult Hb during
intrauterine or exchange transfusion, resulting in low
erythropoietin levels and reticulocyte count.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
9
o Continued destruction of neonatal RBCs by high
titers of circulating maternal antibodies also contributes
the development of anemia. Weekly Hcts and reticulocyte
count need to be monitored after discharge until renewed
erythropoiesis is noted. Administration of recombinant.
Human erythropoietin (rh-EPO) has been shown to
minimize the need for transfusion in these newborns.
Potential complications of exchange transfusion
include the following
Cardiac - Arrhythmia, volume overload, congestive
failure, and arrest
Hematologic – Over heparinization, neutropenia,
thrombocytopenia, and graft versus host disease
Infectious - Bacterial, viral (cytomegalovirus [CMV],
human immunodeficiency virus [HIV], hepatitis), and
malarial
Metabolic - Acidosis, hypocalcemia, hypoglycemia,
hyperkalemia, and hypernatremia
Vascular - Embolization, thrombosis, necrotizing
enterocolitis, and perforation of umbilical vessel
Systemic – Hypothermia
CONCLUSION
Haemolytic Disease of the New Born(HDN) is
caused by alloimmune antibodies from the mother to the
foetus if there is incompatibility in the blood group of the
foetus inherited from the father and that of the
mother.This can be prevented by early premarital
counselling and proper antenatal care and
management.The titre of the antibodies should be
monitored.
REFERENCES
1. Van Der Schoot CE, Tax GH, Rijnders RJ, de Haas M, Christiaens GC. Prenatal typing of Rh and Kell blood group
system antigens, the edge of a watershed. Transfus Med Rev, 17(1), 2004, 31-44.
2. Moise KJ. Management of Rhesus Alloimmunization in Pregnancy. Obstet Gynecol, 112(1), 2008, 164-76.
3. Kaplan M, Na'amad M, Kenan A et al. Failure to predict hemolysis and hyperbilirubinemia by IgG subclass in blood
group A or B infants born to group O mothers. Pediatrics, 123(1), 2009, e132-7.
4. Luchtman-Jones L, Schwartz AL and Wilson DB..The Blood and Hematopoietic System. In, Fanaroff AA, Martin RJ,
eds. Neonatal-Perinatal Medicine-Diseases of the Fetus and Infant. Vol 2. 8th ed. St. Louis, Mo, Mosby, 2006, 1287-
1356.
5. Martin JA, Hamilton BE, Sutton PD et al. Births, final data for 2002. Natl Vital Stat Rep, 52, 2002, 1-116.
6. Eder AF. Update on HDFN, New Information on Long-Standing Controversies. Immunohematol, 22(4), 2006, 188-95.
7. Bowman JM. Hemolytic Disease (Erythroblastosis Fetalis). In, Creasy RK, Resnik R. Maternal-fetal medicine. 4th
edition. Philadelphia, WB Saunders, 1999, 736-767.
8. Van Der Schoot CE, Tax GH, Rijnders RJ, de Haas M, Christiaens GC. Prenatal typing of Rh and Kell blood group
system antigens, the edge of a watershed. Transfus Med Rev, 17(1), 2004, 31-44.
9. Moise KJ. Management of Rhesus Alloimmunization in Pregnancy. Obstet Gynecol, 112(1), 2008, 164-76.
10. Kaplan M, Na'amad M, Kenan A et al. Failure to predict hemolysis and hyperbilirubinemia by IgG subclass in blood
group A or B infants born to group O mothers. Pediatrics, 123(1), 2009, e132-7.
11. Luchtman-Jones L, Schwartz AL and Wilson DB..The Blood and Hematopoietic System. In, Fanaroff AA, Martin RJ,
eds. Neonatal-Perinatal Medicine-Diseases of the Fetus and Infant. Vol 2. 8th ed. St. Louis, Mo, Mosby, 2006, 1287-
1356.
12. Martin JA, Hamilton BE, Sutton PD et al. Births, final data for 2002. Natl Vital Stat Rep, 52, 2002, 1-116.
13. Eder AF. Update on HDFN, New Information on Long-Standing Controversies. Immunohematol, 22(4), 2006, 188-95.
14. Bowman JM. Hemolytic Disease (Erythroblastosis Fetalis). In, Creasy RK, Resnik R. Maternal-fetal medicine. 4th
edition. Philadelphia, WB Saunders, 1999, 736-767.
15. Smits-Wintjens VE, Walther FJ, Rath ME et al. Intravenous Immunoglobulin In Neonates With Rhesus Hemolytic
Disease, A Randomized Controlled Trial. Pediatrics, 127(4), 2011, 680-6.
16. Moise KJ. Hemolytic Disease of the Fetus and Newborn. In, Creasy R.K, Resnik, R. Maternal-fetal Medicine, Principles
and Practice. 6th edition. Philadelphia, WB Saunders, 2008, 477-503.
17. Bianchi DW, Avent ND, Costa JM and van der Schoot CE. Noninvasive Prenatal Diagnosis Of Fetal Rhesus D, Ready
For Prime(R) Time. Obstet Gynecol, 106(4), 2005, 841-4.
18. Rouillac-Le SC, Puillandre P, Gillot R et al. Large-Scale Pre-Diagnosis Study Of Fetal Rhd Genotyping By Pcr On
Plasma Dna From Rhd-Negative Pregnant Women. Mol Diagn, 8(1), 2004, 23-31.
19. Gottstein, R.and Cooke, R.W. Systematic review of intravenous immunoglobulin in haemolytic disease of the newborn.
Arch Dis Child Fetal Neonatal Ed, 88(1), 2003, F6-10.
20. Hammerman C, Vreman HJ, Kaplan M and Stevenson DK. Intravenous Immune Globulin In Neonatal Immune
Hemolytic Disease, Does It Reduce Hemolysis?. Acta Paediatr, 85(11), 1996, 1351-3.
Inter. J. of Pharmacotherapy / 5(1), 2015, XX-XX.
10
21. Elalfy MS, Elbarbary NS and Abaza HW. Early Intravenous Immunoglobin (Two-Dose Regimen) In The Management
Of Severe Rh Hemolytic Disease Of Newborn--A Prospective Randomized Controlled Trial. Eur J Pediatr, 170(4),
2011, 461-7.
22. Madan A, MacMahon JR and Stevenson DK. Neonatal Hyperbilirubinemia. In, Taeusch HW, Ballard RA, eds. Avery's
Diseases of the Newborn. 8th ed. Philadelphia, Pa, Elsevier Saunders, 2005, 1226-1256.
