This document provides an overview of neonatal alloimmune thrombocytopenia (NAIT). It discusses that NAIT is caused by maternal antibodies destroying fetal platelets, which can lead to intracranial hemorrhage in the fetus or newborn. The document outlines the diagnosis, which involves testing the mother and father for platelet antigens, as well as the management approaches for the affected newborn and fetus in subsequent pregnancies. These include transfusion of platelets for low counts with bleeding, and administration of intravenous immunoglobulin and corticosteroids to the mother during pregnancy. The goal of antenatal management is to prevent intracranial hemorrhage in the fetus.

1. NEONATAL ALLOIMMUNE
THROMBOCYTOPENIA
DR.RAVI KUMAR
PEDIATRIC RESIDENT
MGMCRI

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OBJECTIVES
Introduction
Epidemiology
Morbidity
Pathophysiology
Natural History
Diagnosis
Management
Antenatal Management

3. INTRODUCTION
NAIT - Neonatal AlloImmune Thrombocytopenia
Common cause of early onset neonatal thrombocytopenia
 Associated with significant fetal and neonatal morbidity and mortality
The most dreadful complication - Intracranial haemorrhage as a result of severe
thrombocytopenia leading to death or major neurological damage
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5. EPIDEMIOLOGY
Incidence: 1/2000 pregnancies
Anti – HPA-1a accounts for 80-90% of cases in Caucasians
10 - 15% of cases are associated with anti - HPA- 5b
In Asians NAIT occurs secondary to anti-HPA-4
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6. MORBIDITY
20% of affected - Intracranial hemorrhage (ICH)
20% of survivors of ICH - long term neurodevelopmental sequelae
About 50% of ICH occur in utero
Recurrence rate >75% for subsequent pregnancies, requiring referral to high risk
obstetrics clinic for subsequent pregnancies
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7. PATHOPHYSIOLOGY
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NAIT is caused by maternal
alloantibodies directed against
incompatible fetal platelet antigens
inherited from the father.
In the setting of an antigen-negative
mother, transplacental passage of
maternal immunoglobulin G (IgG)
antibodies results in the accelerated
destruction of fetal platelets expressing
the corresponding antigen.

8. NATURAL HISTORY
Following delivery : Petechiae, Ecchymoses & Cephalohematoma
Some are asymptomatic, with incidentally detected severe thrombocytopenia on first
day of life.
One of the most serious complications is ICH and can occur in the fetal or neonatal
period
The majority of IC bleeding occurs after 30 weeks of gestation, but some studies
reported to appear as early as 20 weeks.
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9. Cephalohematoma
Ecchymosis
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10. CRITERIA
All the following criteria are necessary to diagnose fetal/neonatal alloimmune
thrombocytopenia :
1. Fetal or Early onset Neonatal thrombocytopenia
2. Identification of a paternal, fetal, or neonatal platelet antigen that the mother lacks
3. Identification of maternal antibodies to that antigen
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11. DIAGNOSIS
When NAIT is suspected, blood should be collected from the mother and father for
antigen screening for detection of HPA 1, 3, and 5 ( 90% of cases )
If the diagnosis is strongly suspected/ Initial evaluation is negative, further testing for
HPA 9 and 15 can be done
Level of maternal HPA -1a antibodies
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MANAGEMENT
AFFECTED NEONATE
CONFIRM
THROMBOCYTOPENIA ON
REPEAT BLOOD SAMPLE
IF PLATELET COUNT
<1,00,000
SUSPECT
NAIT IF CAUSE IS UNCERTAIN
NEONATAL STUDIES
1. Careful History &
Examination
2. Test for DIC
3. R/O TORCH/KMP/
TAR Syndrome
4. NSG to r/o ICH
MATERNAL STUDIES
1. Careful Antenatal History
2. Maternal CBC
URGENT STUDIES
Maternal & Paternal Sample for
detection of Antibodies against HPA-
1a

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MANAGEMENT
PLATELET COUNT <30,000
& CLINICALLY SIGNIFICANT
BLEEDING
TRANSFUSE PLATELET
10-20ml/kg
POST
TRANSFUSIO
N PLATELET
> 30,000
POST
TRANSFUSIO
N PLATELET
< 30,000
Perform Daily Platelet,
Transfusion Irradiated
Washed Plasma
Depleted Maternal
Platetlet
PLATELET COUNT > 30,000 &
NO E/O BLEEDING
Observe, Follow Daily Platelet,
Await For Initial Serological
Studies & Do Not Transfuse
Consider 2nd Dose of RDP,
Administer IV IG (1g/kg/dose)
If Platelet Count is <1,00,000
With clinical bleeding

14. GUIDELINES FOR PLATELET
TRANSFUSION
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15. ANTENATAL MANAGEMENT
Treatment options include :
1. Fetal Blood Sampling (FBS)
2. Maternal intravenous immunoglobulin (IVIG)
3. Maternal corticosteroid treatment
4. Intrauterine platelet transfusion (IUT)
5. Early delivery
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16. FETAL BLOOD SAMPLING
FBS is used to diagnose and determine
Degree of thrombocytopenia
Intra uterine platelet transfusion
To measure response to direct therapy
However, there are significant risks associated with this procedure, including bleeding,
premature delivery and death.
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Prenatal treatment will be based on the severity of the thrombocytopenia and the
presence or absence of ICH in the previously affected fetus.

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Current recommendations:
 Maternal IVIG (1 to 2g/kg/week) &
 +/- Prednisone (0.5 to 1 mg/kg/day)
 Starting at 12 wk (or) 20 to 26 wks of gestation, depending upon whether the
morbidity or mortality previously affected fetus

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Most recent studies showed that the combination of IVIG and steroids is the most
efficient treatment.
Elective cesarean section is recommended in most countries, regardless of ICH
status, to avoid ICH.
Mothers who delivered an infant with NAIT should be followed in high-risk obstetric
clinics during all future pregnancies

20. TAKE HOME MESSAGE
Newborn with petechiae & ecchymosis with severe thrombocytopenia in the first day of life,
should be strongly suspected NAIT
Clinically, NAIT is a diagnosis of exclusion.
Intracranial hemorrhage is responsible for most neonatal morbidity and mortality, occurs in 7
to 20 percent of cases
Random-donor platelet transfusions +/- IVIG is the first line of therapy
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21. THANK YOU
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