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Rh Disease and Neonatal Alloimmune
Thrombocytopenia Purpura – What’s new?
Kenneth J. Moise, Jr., M.D. Professor of Obstetrics and Gynecology
Professor of Pediatric Surgery
The University of Texas Health Science Center
(UTHealth) Medical School at Houston
The Texas Fetal Center
Children’s Memorial Hermann Hospital
• Dr. Moise has received research support from
Sequenom, Inc. to evaluate the use of free fetal
DNA for fetal RHD typing in a multi-center
clinical trial
• Dr. Moise serves as a consultant to LabCorp,Inc.
• Dr. Moise receives royalty payments for
authorship of various chapters in UpToDate®
Disclaimer
• Evaluate new DNA technologies in the
management of the red cell alloimmunized
pregnancy and incorporate these methodologies
into clinical practice
• Describe current evidenced-based management
for the treatment of the pregnancy affected by
fetal/neonatal alloimmune thrombocytopenia
purpura
Objectives
DNA testing
Anti-D Anti-C Anti-c
+ - +
Anti-E Anti-e
- +
RED CELL ALLOIMMUNIZATION
Paternal Zygosity
Caucasian
Dce/dce (heterozygous RhD) – 90%
Dce/Dce (homozygous RhD) – 10%
Black
Dce/dce (heterozygous RhD) – 41%
Dce/Dce (homozygous RhD) – 59%
RED CELL ALLOIMMUNIZATION
Paternal Zygosity
RED CELL ALLOIMMUNIZATION
Paternal Zygosity
Buffy coat (maternal WBC’s =
DNA)
Maternal plasma (mixed
free maternal and fetal DNA)
RED CELL ALLOIMMUNIZATION
Free Fetal DNA
New assay available from Sequenom®
3 male identifiers
92 SNP’s (6 must be different between mother and fetus)
Results
– RhD positive, male – valid result
– RhD negative, male – valid result
– RhD positive female – valid result
– Rh negative, female – need identifiers
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Rh D positive
result Valid
Rh D negative Reflex testing
Male fetus Female fetus
Reflex testing 92 SNP’s At least 6
different
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Three collections from 120 patients
• Median: 12.4 weeks (10.6 – 13.9 wks)
• Median: 17.6 wks (16.0 – 20.9 wks)
• Median: 28.7 wks (27.9 – 33.9
RED CELL ALLOIMMUNIZATION
Free Fetal DNA
Moise et al. Am J Obstet Gynecol 2012; 206:S315
Parameter First Trimester Second Trimester Third Trimester
Sensitivity (95% CI) 98.6% (0.93 - 1.0) 100% (0.95 - 1.0) 100% (0.95 - 1.0)
Specificity (95% CI) 100% (0.90 - 1.0) 96.8% (0.83 - 0.99) 94% (0.80 - 0.99)
Accuracy (95% CI) 99.1% (0.95 - 1.0) 99.1% (0.95 - 1.0) 98.1% (0.93 - 1.0)
Moise et al. Am J Obstet Gynecol 2012; 206:S315
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
38% of RhD negative patients will
carry an RhD negative fetus
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Scenario #1 Non-invasive testing free fetal DNA testing used to
determine fetal RhD status
Antenatal Rhesus immune globulin held if RhD
negative fetus
Continue standard cord serology after birth to
determine need for Rh immune globulin
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Szcepura et al. BMC Pregnancy and Childbirth 2011;11:5
Scenario #2 Non-invasive testing free fetal DNA testing used to
determine fetal RhD status
Antenatal Rhesus immune globulin held if RhD
negative fetus
No cord serology done after birth; forego Rhesus
immune globulin held if RhD negative fetus
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Szcepura et al. BMC Pregnancy and Childbirth 2011;11:5
Breakeven costs for non-invasive testing
Scenario #1: £18.43 ($29.17)
Scenario #2: £25.0 ($ 39.57)
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
Szcepura et al. BMC Pregnancy and Childbirth 2011;11:5
Non-invasive sensitivity New cases (Scenario #1) New cases (Scenario #2)
94.8% 54 744
96.0% 42 573
98.0% 21 283
99.0% 10 141
99.9% 1 14
RED CELL ALLOIMMUNIZATION
Free Fetal DNA Testing
New cases of RhD alloimmunization in England and Wales
Szcepura et al. BMC Pregnancy and Childbirth 2011;11:5
MCA
Doppler
< 15 °
RED CELL ALLOIMMUNIZATION
MCA Doppler
Ruma et al. Am J Obstet Gynecol 2009;397.e1-397.e3
RED CELL ALLOIMMUNIZATION
MCA Doppler
Abel et al. Am J Obstet 2003;189: 986-9 33 cm/sec
38 cm/sec
39 cm/sec
29 cm/sec
RED CELL ALLOIMMUNIZATION
MCA Doppler
Swartz et al. Obstet Gynecol 2009;113:1255-6
RED CELL ALLOIMMUNIZATION
MCA Doppler
515 MCA measurements in 66 fetuses
Intrauterine
Transfusion
Moderate Anemia Severe Anemia
1st IUT
↓
← 2nd IUT
← 3rd IUT
LOTUS trial
IUT’s between 1988 - 2008
291 children (85% participation)
Median age 8.2 yrs (range: 2 – 17 years)
Bayley Scales of Infant Development, Weschler
Preschool of Primary Scale of Intelligence,
Weschler Intelligence Scale for Intelligence
RED CELL ALLOIMMUNIZATION
Long Term Follow-up
Lindenburg et al. Am J Obstet Gynecol 2012; 205:141.e1-8
Overall neurodevelopmental impairment – 4.8%
Cerebral palsy – 2.1%
– Dutch baseline: 0.7% @ 32 – 37 wks; 0.2% > 32
wks
Severe developmental delay – 3.1%
― Dutch baseline: 2.3%
Bilateral deafness – 1.0%
RED CELL ALLOIMMUNIZATION
Long Term Follow-up
Lindenburg et al. Am J Obstet Gynecol 2012; 205:141.e1-8
RED CELL ALLOIMMUNIZATION
Long Term Follow-up
Lindenburg et al. Am J Obstet Gynecol 2012; 205:141.e1-8
Parameter NDI No NDI OR
Mild hydrops 36% 18% 4.3 (1.2 – 15.3)
Severe hydrops 29% 6% 9.9 (2.4 – 40.5)
Hgb at first IUT 4.2 + 1.9 5.6 + 2.4 p =0.032
Z hemoglobin -8.1 -7.3 NS
No of IUT’s 4 (1-5) 3 (1-6) 1.7 per IUT
Gest Age < 32 wks 14% 1% 12.8 (2.1 - 79.5)
Severe neonatal
morbidity
43% 6% 13.1 (4.0 - 42.4)
Fetal/Neonatal
Alloimmune
Thrombocytopenia
Platelet Antibodies
• HPA-1a most common antigen in Caucasians
• Incidence: 1 in 1000 neonates
• Detection:
– 1st neonate born w/ thrombocytopenia
– Sister of patient with this history
• Rate of recurrence in subsequent sibs: 85 – 90%
Platelet Antigens
IIba III
IIbb vWF
fibronectin
fibrinogen
Ca 2+
S S
Platelet Antibodies
HPA-1a PlA1, Zwa GPIIIa 97.7%
HPA-1b PlA2, Zwb 26.5%
HPA-2a Kob GPIb 99.3%
HPA-2b Koa, Sibb 14.6%
HPA-3a Baka, Leka GPIIb 87.7%
HPA-3b Bakb 64.1%
HPA-4a Pena, Yuka GPIIIa 99.9%
HPA-4b Penb, Yukb 0.2%
HPA-5a Brb,Zavb GPIa 99.2%
HPA-5b Bra, Zava, Hca 20.6%
Platelet Antibodies
Specificity N Percent
HPA-1a 304 73.3
HPA-1a and 5b 11 2.7
HPA-5b 79 19.0
HPA-3a 8 1.9
HPA-2b 3
HPA-1b 3
HPA-5a 2
HPA-8b 1
HPA-12wb 1
HPA-13wb 1
Oea 1
HPA-4b 1
Fetal/Neonatal Disease
Intracranial hemorrhage • 10 - 20% of cases
• 75% of cases antenatal
• Mostly parenchymal
• Reported as early as 20 weeks
• Usually occurs after 30 weeks
• 100% recurrence if previous affected sibling
• Not predicted by maternal antibody levels
Evaluation
History of:
- Previous neonate with thrombocytopenia of unknown etiology
- Previous infant with platelet count < 50,000mm3 regardless of the
presumed etiology
- Previous fetus or neonate with intracranial hemorrhage of
uncertain etiology
Maternal thrombocytopenia
Reference laboratory testing:
- Maternal platelet antigen testing
- Paternal platelet antigen typing
- Maternal platelet HPA antibody
testing using sensitive assays
Evaluate for maternal anti-
platelet antibodies OR
history of autoimmune
thrombocytopenia
Yes
No
Evaluation
Incompatibility at HPA (1, 2,
3, 4, 5, 6, 9, 15)
Specific maternal anti-HPA
antibody to one of the
above present
Diagnosis of fetal
or neonatal
alloimmune
thrombocytopenia
No incompatibility at HPA
loci
Nonspecific or no anti-
platelet antibody testing
using sensitive assays
Incompatibility at HPA (1, 2,
3, 4, 5, 6, 9, 15)
Specific maternal anti-HPA
antibody to one of the
above NOT present
Test for maternal antibodies
at 30 weeks gestation
against father’s)
Detection of positive anti-
HPA antibodies that
react to paternal
platelets
Repeat maternal anti-HPA
antibody testing and
cross-match with
paternal platelets at 12,
24, and 32 wks EGA
No further evaluation
necessary
negative
negative
positive
Treatment
Previous infant w/ platelets
but no ICH
EGA 12 weeks:
IVIG (1 g/kg/wk)
EGA 20 weeks:
IVIG (1 g/kg/wk) and
predisone (0.5
mg/kg/day
OR
IVIG ( 2 g/kg/wk)
Previous fetus or infant with
ICH diagnosed > 28
weeks EGA
Previous fetus with ICH
diagnosed < 28 weeks
EGA
EGA 20 weeks:
IVIG to 3 g/kg/week
OR
add Prednisone
(0.5 mg/kgday)
EGA 20 weeks:
Add Prednisone
(1 mg/kg/day)
EGA 12 weeks:
IVIG (2 g/kg/wk)
EGA 32 weeks:
IVIG (2 g/kg/wk) and
predisone (0.5
mg/kg/day)
EGA 28 weeks:
IVIG (2 g/kg/wk) and
predisone (0.5
mg/kg/day)
Treatment (IVIF preparations)
Pacheco et al. Obstet Gynecol 2011;118:1157-63
• Side- effects
Flushing
Myalgia
Nausea
Hypotension
Fever and chills
Hemolytic anemia
Palmar desquamation
Headache
Treatment with IVIG
• Premedicate with acetominophen (1000 mg)
and diphenyhydramine (25-50 mg IV)
• Pre-hydrate; slow infusion
• Steroids
Decadron – 10- 20 mg orally
Decadron – 1 gram/ intravenously
Treatment with IVIG
• Give first dose in hospital
• Infusion rate: 1 gr/kg over 4 – 5 hours
• No more than 1 gr at one setting
• Give first dose in hospital setting
• Sequential doses with home therapy – IVIG
America
Treatment with IVIG
• Maternal platelephresis 3 days prior to planned
Csection
• Arrange donor infectious disease testing
May have positive marker from IVIG
FDA wavier to use designated platelets
• Do not wash (activates the platelets)
• Check cord platelet count usly
Delivery Considerations
Treatment
Previous infant w/ platelets
but no ICH
EGA 37 – 38 weeks:
• Csection after lung
maturity documented
• Vaginal delivery if
cordocentesis > 32 weeks
shows platelets > 100,0003
Previous fetus or infant with
ICH diagnosed > 28
weeks EGA
Previous fetus with ICH
diagnosed < 28 weeks
EGA
EGA 35 – 37 weeks:
• Csection after lung
maturity documented
• Vaginal delivery if
cordocentesis > 32 weeks
shows platelets > 100,0003
Which of the following is the most problematic
situation for determining the accuracy of free
fetal DNA testing for fetal RhD status?
a) RhD positive, male fetus
b) RhD negative, female fetus
c) RhD positive, female fetus
d) RhD negative, male fetus
Questions
A previous patient with NAIT experienced a
pregnancy complicated by a fetal intracranial
hemorrhage that was detected by ultrasound at 26
weeks gestation. The initial treatment for this
pregnancy would be to initiate:
a) 1 g/kg intravenous immune globulin weekly
b) 0.5 mg/kg/day oral Prednisone
c) 2 g/kg intravenous immune globulin weekly
d) 1 mg/kg/day oral Prednisone
Questions
texasfetalcenter.org
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