"Rwandan National Neonatal Protocol: Hematology"
by Dr. Aicha Uwamahoro.
Introduction.
I am Dr. Aicha Uwamahoro, a pediatrician
working with Rwanda Pediatric Association.
Today I'll be talking about neonatal hematology.
Overview.
By the end of the chapter, participants
will be able to explain the etiology, investigation,
and treatment for anemia, explain why infants develop
physiologic anemia, identify two risk
factors for exaggerated anemia, recognize
two indications for red blood transfusion
in the setting of exaggerated anemia,
explain the etiology, investigation, and treatment
for bleeding, explain the etiology, investigation,
and treatment for polycythemia.
Etiology, investigation, and treatment: Anemia
We will start the lesson on anemia
with some physiologic background material.
During the first week of life, erythropoietin
and fetal hemoglobin production decrease in response
to the rich oxygen supply, which leads to physiologic anemia.
Some newborns usually reach a physiologic nadir
with hemoglobin of 9 to 11 at 6 to 12 weeks of age.
Premature newborns usually have an earlier and more severe
physiologic nadir with hemoglobin of 8 to 10
at 5 to 10 weeks of age.
At nadir, there is typically insufficient oxygen delivery
to tissues, which leads to a rise in erythropoietin levels
and production of adult hemoglobin.
Therefore, physiologic anemia really
requires medical treatment.
The physiologic nadir can be exaggerated
by a number of factors.
The first is obstetric blood loss,
which can take the form of placental abruption, placenta
previa, or placental laceration during cesarean section.
Others include fetoplacental bleeding, phlebotomy,
and early cord clamping less than 1 minute after delivery.
Hemorrhage can also be a factor, whether it is cephalohematoma,
subgaleal, or intracranial hemorrhage, or in the form
of bleeding into abdominal organs.
The physiologic nadir can also be exaggerated by: hemolysis,
diminished red blood cell production,
and repeated blood draws.
Hemolysis can be due to hereditary blood cell
disorders such as G6PD deficiency,
red blood cell membrane defects, all hemoglobinopathies,
acquired hemolysis from infection,
and immune factors such as ABO, rhesus, or minor blood group
incompatibility.
Diminished red blood cell production
may be caused by iron deficiency, infection,
or medications.
To avoid excess blood draws, it is important
to be mindful of the number of laboratory tests ordered
and avoid routine daily blood testing unless necessary
for management.
When diagnosing anemia, it is important to perform laboratory
testing, such as FBC, reticulocyte count, smears,
and Coombs test, a physical exam,
and to explore the patient's family history.
Before deciding to give a red blood cell transfusion,
clinical condition, hematocrit value, and trend over time,
and etiology of the anemia are all needed.
Indications for a red blood cell transfusion
include significant cardiorespiratory distress,
blood loss faster than the rate at which
the newborn can generate red blood cells, or severe anemia.
Hemoglobin below 7 grams per deciliter
with poor reticulocytosis or poor newborn growth
despite adequate feeding.
The volume of red blood cell transfusion
depends on the current and goal hemoglobin or hematocrit,
ongoing blood loss and expected tolerance of transfusion.
The presence of chronic lung disease of other conditions
in which transient fluid overload
would be poorly tolerated.
Tolerance of transfusion is based
on whether the circulating volume is low due to acute
or chronic blood loss.
A typical transfusion volume is 10 to 15 mL/kg
given over three to four hours.
A second transfusion, preferably from the same donor,
may be needed if the anemia is not adequately corrected.
If post transfusion hematocrit is needed,
wait until at least 1 hour after completion of the transfusion.
Whole blood should be given to correct anemia
for rapid blood loss.
If there is concern for severe anemia
and hemoglobin/hematocrit is not available,
give 10 to 20 mL/kg and continue monitoring the infant.
Preventing anemia is always better than treating it.
Iron deficiency is associated with worse cognitive
development making prevention extremely important.
Newborns at risk for iron deficiency
include those who have experienced substantial blood
loss or are premature should receive
supplemental iron once they are tolerating full enteral feeds.
The dose for prevention is 2 milligrams per kg per day,
and the treatment dose for anemia
is 4 milligrams/kg/day.
Iron in syrup is available in several different salt forms
and concentrations.
Each salt contains a different proportion of elemental iron,
so the medication label should be checked carefully
to confirm the concentration of elemental iron contained
in the syrup.
Parents should be instructed on the exact volume
to administer since accidental overdose of iron
can result in serious illness.
Etiology, investigation, and treatment: Bleeding
Bleeding has many possible causes.
The most common being deficiency of clotting factors,
inherited clotting abnormalities, and low or poor
functioning platelets.
It is important to determine whether
a newborn with a bleeding disorder is otherwise sick
or well.
Sick newborns tend to have disseminated
intravascular coagulapathy, platelet consumption, or liver
dysfunction.
Well newborns tend to have immune mediated
thrombocytopenia, hemorrhagic disease
of the newborn, or hereditary clotting factor deficiencies.
Three lab tests should be conducted when assessing
bleeding in a newborn.
This includes FBC including platelet counts, smear,
and coagulation studies, if possible.
To treat newborn bleeding, give vitamin K if not given at birth
or if the documentation is unclear.
The dose for term infant is 1 milligram intramuscular
and for preterm infant or those weighing less than 1.5 kg,
it is 0.5 milligram.
Give platelet and fresh frozen plasma if available,
as well as red blood cell transfusion as needed.
Etiology, investigation, and treatment: Polycythemia
Polycythemia occurs when hemoglobin levels
are very high.
In the newborn, it is defined as venous hemoglobin
over 22 grams per deciliter or hematocrit over 65%.
Placental red blood cell transfusion,
for example, delayed cord clamping,
maternal fetal hemorrhage, or twin-to-twin transfusion
can increase the risk of polycythemia
as can placental insufficiency due to maternal hypertension
syndromes, postmature, and small for gestational age
newborns, high altitude, maternal cardiovascular or
pulmonary conditions, or maternal smoking
causing chronic hypoxia.
Other risk factors include: certain maternal medication,
maternal diabetes, or hemoconcentration
due to dehydration.
Polycythemic newborns have increased blood viscosity,
which can lead to central nervous system,
cardiorespiratory, and other symptoms.
CNS symptoms include poor feeding, lethargy,
and seizures.
Possible cardiorespiratory symptoms
are cyanosis, tachypnea, respiratory distress,
and pulmonary hypertension.
Polycythemic newborns may also experience
jaundice, thrombosis, hemateria, proteinuria, and hypoglycemia.
Polycythemia is treated with an isovolumetric divisional
partial exchange transfusion.
Symptomatic newborns with a hematocrit over 65%
or asymptomatic newborns with a hematocrit over 70%
should be treated.
The volume of transfusion is typically
15 to 25 mL/kg body weight, but depends
on the observed and desired hematocrit,
which is usually 50%.
Circulating blood volume is usually
estimated at 80 mL/kg body weight.
Slowly withdraw the circulated volume of blood
and replace it with normal saline.
Ideally, one provider should draw blood off
of a large bore IV while a second provider infuses
the replacement volume of IV fluid to keep
the circulating blood volume stable.
Case studies.
To review, we will practice with some case studies.
The first concern, Emmanuel, a full-term newborn.
He appears well but has perinatal risk factors
for sepsis.
You send an FBC, and the hemoglobin comes back at 18,
hematocrit of 54%.
Are you concerned?
Does Emmanuel require any treatment?
No.
There is no cause of concern.
The normal hemoglobin range for a newborn is 15 to 18
or hematocrit of 45% to 55%.
Emmanuel is polycythemic due to relative intrauterine hypoxia.
He does not require any treatment,
which is only indicated if hemoglobin
is over 22 grams with symptoms of polycythemia
or over 23.3 grams per deciliter regardless of symptoms.
The corresponding hematocrit value at 65% and 70%.
Our next patient is Eugenie, who was born at 29 weeks gestation.
She is now seven weeks old and slightly pale,
but otherwise, appears normal.
You send an FBC and find that her hemoglobin is 9,
meaning her hematocrit is 27%.
Are you concerned?
Does Eugenie require any treatment?
There is no reason of concern.
Physiologic anemia is common in infants,
especially immature newborn who have
a nadir hemoglobin of 8 to 10 or hematocrit of 24% to 30%.
Eugenie should be treated with iron,
but she does not need a red blood cell transfusion
as her levels will raise spontaneously.
A transfusion is only indicated if she
developed cardiorespiratory instability,
is unable to gain weight, or has significant ongoing blood loss.
Solange, who was born at 29 weeks gestation,
is the subject of our final case study.
Now seven weeks old, she's having
many apnea spells, despite caffeine and is growing poorly.
After birth, she had a large cephalohematoma.
During hospitalization, she has required multiple blood tests.
You send for an FBC for her and find
that her hemoglobin is 6.5 grams per deciliter,
a hematocrit of 19.5%.
Is this physiologic or pathologic anemia or both?
What contributed to her anemia?
This is pathologic anemia exacerbating
physiologic anemia.
Blood loss due to cephalohematoma and phlebotomy
exacerbated the physiologic anemia
seen in all infants and more severely in premature infants.
Other factors that can exacerbate
the physiologic anemia are obstetric blood loss,
fetoplacental bleeding, other kinds of hemorrhage,
hemolysis, and diminished red blood cell production.
Does she need a blood transfusion?
Why, or why not?
Solange does need a blood transfusion
because her anemia is severe with hemoglobin less
than 7 grams per deciliter.
She has cardiorespiratory instability and poor growth.
Summary.
Having finished this chapter, you
should be able to explain the etiology, investigation,
and treatment for anemia; explain why infants develop
physiologic anemia, identify two risk
factors for exaggerated anemia, recognize
two indications for red blood transfusion
in setting of exaggerated anemia,
explain the etiology, investigation,
and treatment for bleeding, explain
the etiology, investigation, and treatment for polycythemia.
The following are key points on hematology.
Newborns are born with a physiologic polycythemia
due to relative hypoxia in utero,
normal hemoglobin for newborn is 15 to 18.
Normal hematocrit for newborn is 45% to 55%.
Newborns develop physiologic anemia
because erythropoietin and fetal hemoglobin production
decreases in response to relatively rich oxygen supply.
Red blood cell transfusion is indicated
if the patient has cardiorespiratory instability,
is unable to gain weight, or has significant ongoing blood loss.
Newborn polycythemia is when venous hemoglobin
is over 22 grams per deciliter, hematocrit over 65%.
It should be treated with an isovolumetric dilutional
partial exchange transfusion.
Thank you.
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