1 / 25

Alloimmune Thrombocytopenia

Michael F. McNamara, DO Sanford Maternal Fetal Medicine. Alloimmune Thrombocytopenia. No disclosures. Platelet Disorders in Pregnancy. Gestational thrombocytopenia Idiopathic thrombocytopenia (ITP) Thrombotic thrombocytopenia (TTP) Alloimmune thrombocytopenia (NAIT).

ronan-tyson
Download Presentation

Alloimmune Thrombocytopenia

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Michael F. McNamara, DO Sanford Maternal Fetal Medicine Alloimmune Thrombocytopenia

  2. No disclosures

  3. Platelet Disorders in Pregnancy • Gestational thrombocytopenia • Idiopathic thrombocytopenia (ITP) • Thrombotic thrombocytopenia (TTP) • Alloimmune thrombocytopenia (NAIT)

  4. Gestational Thrombocytopenia • Dilution effect • Increase of platelet destruction • No therapy needed

  5. Idiopathic Thrombocytopenia • 1-3 / 1000 pregnancies • Pregnancy not usually altering disease course • Therapy • Steroids • IVIG • Splenectomy

  6. Thrombotic ThrombocytopeniaPurpura (TTP) • TTP/HUS, may be confused with pre eclampsia • Microangiopathic hemolytic anemia • Thrombocytopenia • Neurologic changes (headache, lethargy) • Thrombotic occlusions in multiple small vessels • Therapy plasma exchange, platelet transfusions

  7. Alloimmune Thrombocytopenia • Also known as Neonatal Alloimmune Thrombocytopenia (NAIT) • 0.2 -1 per 1000 deliveries • Low fetal platelets due to maternal antibodies • Index case usually affected • Antenatal diagnosis often by ultrasound with findings of intracranial hemorrhage

  8. Case Study • 25 year old female • Gravida 5, para 2 • Two previous term vaginal deliveries • Petechiae, bruising, platelets < 10,000 • Counseled on further pregnancies, need of treatment

  9. Case Study • Presented at 14 weeks gestation • Genetic counseling, history reviewed • Same paternity as previous infants • Father of baby not available for testing (zygosity)

  10. Case Study • Diagnostic testing (platelet antigen) • Maternal • Blood HPA 1b/1b • Fetal • Amniotic fluid HPA 1a/1b

  11. Case Study • Preventative therapy • IVIG 1 gram / kg weekly • Prednisone 1mg /kg daily

  12. Case Study • Antenatal Course • Gestational diabetes • Severe headaches with IVIG therapy • Elevated liver enzymes due to percocet use secondary to headaches

  13. Case Study • Antenatal steroids at 33 weeks gestation • Elected cesarean for delivery with tubal ligation • Vaginal delivery if umbilical cord sampling performed with normal fetal platelet count • Delivery at 37 weeks, uncomplicated • Female infant 5 lbs, 4 oz

  14. Alloimmune thrombocytopenia • Also know as Neonatal Alloimmunethrobocytopenia (NAIT) • Incidence 0.2 -1 per 1000 Caucasian births • Maternal antigens against fetal platelets

  15. NAIT • Platelet antigens classified at HPA 1a (PLA1) and HPA 1b (PLA2) • 97% adults phenotype HPA 1a (positive for 1a) • 69% adults homozygous HPA 1a (1a/1a) • 28 % adults heterozygous HPA 1a (1a/1b) • 3 % adults homozygous HPA 1b (1b/1b)

  16. NAIT • Affected pregnancies • Most serious complication • Intracranial hemorrhage 10-20 % of cases • 25-50 % cases diagnosed prenatally • Ultrasound findings of intracranial hematoma, porencephalic cysts

  17. Antepartum Preventive Therapy • Extremely High Risk • Previous baby ICH in second trimester • High risk • Previous baby ICH in third trimester • Moderate risk • Previous baby with thrombocytopenia but no ICH

  18. NAIT • Recurrence risk up to 100% • Thrombocytopenia is severe and happens earlier in subsequent pregnancies • Previous ICH is risk factor for severe thrombocytopenia in next pregnancy • Low platelet count goes lower in subsequent pregnancies without treatment in utero

  19. NAIT – antenatal therapy • IVIG – very uncommon for ICH with IVIG treatment (11/411 for 2.7%) • Prednisone (additionally) – no better than IVIG alone • Umbilical cord sampling – procedure / bleeding risk • Platelet transfusions – unknown efficacy

  20. IVIG Mechanism of Action • Provision of missing immunoglobulins or neutralizing antibodies, restoration of immune function, and/or suppression of inflammatory and immune-mediated processes • Increase the effect of regulatory T cells, contributing to the maintenance of immunologic self-tolerance • Prevention of reticuloendothelial uptake of autoantibody-coated blood cells (eg, platelets, red cells) through blockade of macrophage Fc-receptors

  21. Case Study #2 • Preconception Counseling • Gravida 3, Para 3 with recent neonatal demise from ICH delivered at 38 weeks • Low platelet count • Paternal 1a/1b • Maternal 1b/1b

  22. Case Study #2 • Pregnancy #4, amniocentesis • Fetus - male1b/1b, normal pregnancy • Pregnancy #5, amniocentesis • Fetus – male,1a/1b, affected • IVIG, prednisone, cord sampling • Cesarean at 37 weeks gestation

  23. Case Study #2 • First two pregnancies vaginal deliveries with no complications • Oldest is a male, second oldest female • Recent testing of the female (now an adult), 1b/1b

  24. Case Study #2 • Platelet antigens classified at HPA 1a (PLA1) and HPA 1b (PLA2) • 97% adults phenotype HPA 1a (positive for 1a) • 69% adults homozygous HPA 1a (1a/1a) • 28 % adults heterozygous HPA 1a (1a/1b) • 3 % adults homozygous HPA 1b (1b/1b) • 83% chance of having a baby with 1a/1b

  25. Summary • NAIT cause of neonatal thrombocytopenia • Index case possibly severe problems such as ICH • Decrease complications with in utero therapy, IVIG, prednisone

More Related