207 - Thrombocytopenia in Pregnancy Flashcards
Normal plt count outside pregnancy
165-415K
Thrombocytopenia in pregnancy
<150K
Causes of thrombocytopenia in pregnancy
Prevalence of gestational thrombocytopenia
5-11%
Theorized contributors to gestational thrombocytopenia
Hemodilution and increased clearance
5 key components of gestational thrombocytopenia
1) Onset aytime but usually mid-second to third trimester, usually plt >75
2) Asymptomatic with no hx of bleeding
3) No thrombocytopenia outside of pregnency
4) Plt normalize within 1-2m post-partum
5) low incidence of fetal/neonatal thrombocytopenia (0.1-2.3%)
the risk of gestational thrombocytopenia is ___ times as high among women who had had previous gestational thrombocytopenia as among women who had not had previous gestational thrombocytopenia
14
What % of thrombocytopenia in pregnancy is caused by hypertensive disorders?
5-21%
impact of hypertensive disorders on platelets
not sures, but:
1) incresed activation/consuption
2) decreased function
* thrombocytopenia may be a first sign of impending hypertensive disorder
Risk of neonatal thrombocytopenia in women with hypertensive disorders
1.8%, but unclear if due to maternal disease or to underlying IUGR and prematurity
Maternal immune thrombocytopenia - Definition
1)
- Primary ITP: acquired immune-mediated disorder characterized by isolated thrombocytopenia in the absence of any obvious initiating or underlying cause of thrombocytopenia
- secondary ITP: all forms of immune-mediated thrombocytopenia that are due to an underlying disease or to drug exposure
Maternal immune thrombocytopenia - Causes
Primary: immune
Secondary: APLS, SLE, HIV, HepC, CMV, H. pylori, drugs (heparins, antimicrobials, anticonvulsants, analgesics),
Maternal immune thrombocytopenia - Frequency in pregnancy
1/1’000-1/10’000 pregnancies
Definition of severe ITP, and symptoms
platelets < 50K at any point in the pregnancy or when a clinical decision was made to treat the thrombocytopenia before the delivery of the infant
20% have PPH (as opposed to mild-moderate that is generally asymptomatic)
What % of fetuses born to moms of ITP will have thrombocytopenia (<150K)?
What % will need treatment?
What % have severe hemorrhagic complications?
How long after birth does the plt count nadir?
What % of fetuses born to moms of ITP will have thrombocytopenia (<150K)? 25%
What % will need treatment? 8-15%
What % have severe hemorrhagic complications? <1%
How long after birth does the plt count nadir? within 2 weeks
What is fetal-neonatal alloimmune thrombocytopenia?
maternal alloimmunization to fetal platelet antigens with transplacental transfer of platelet-specific antibody and subsequent platelet destruction in the fetus
(platelet equivalent of hemolytic (Rh) disease)
What is the prevalence of fetal-neonatal alloimmune thrombocytopenia
1/1000-1/3000
T/F: fetal–neonatal alloimmune thrombocytopenia can affect a first pregnancy
What is the prognosis of next pregnancy
TRUE! may be life-threatening
Next pregnancy not necessarily worse
Presentation of mom and fetus/neonate affected by fetal–neonatal alloimmune thrombocytopenia
Mom - asymptomtic, normal plt
Fetus - generalized petechiae or ecchymosis, hemorrhage into viscera and bleeding after circumcision or venipuncture, intracranial hemorrhage (can happen in utero, in plt <50K has 15% risk)
Antigen that causes the most severe fetal-neonatal alloimmune thrombocytopenia? (also the most common in white patients)
human platelet antigen-1a
(HPA-1a)
MCC of thrombocytopenia by trimester:
1st: ITP
2nd: Gestational thrombocytopenia
3rd/PP: preeclampsia, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, acute fatty liver, or disseminated intravascular coagulation. May be ITP
Workup of thrombocytopenia in pregnancy?
CBC and smear
Management of gestational thrombocytopenia in pregnancy
Once diagnosed repeat plt count at each prenatal visit
Repeat platelet count 1-3months PP
At what plt level to transfuse platelets
<70K for epidural
<50K if undergoing major surgery (cesarean)
<30K or symptomatic bleeding
Steroids and thrombocytopenia of hypertensive disorders?
May increase lab value but does not change outcomes
Treatment of ITP in pregnancy including dosage, response time, and peak response time
Treat like non-pregnent patients
Corticosteroids (preferred) or IVIG (if steroid resistant, bad steroid effects, or rapid increase needed) or both are first line
Prednisone: 10-20mg/d (then decrease to minimum amount needed to get effect, 21d); 4-14d; 1-4w
IVIG: 1g/kg once; 1-3d; 2-7d
2nd line: 2nd trimester splenectomy
Effect of medical treatment of ITP on fetus plt levels and outcomes
No reliable effect on plt count or outcomes
Special treatment for ITP patients in pregnancy
CBC q trimester if asymptomatic/remission, more if throbocytopenic
Avoid NSAIDs, Salicylates, trauma
if s/p splenectomy give meningococcal, pneumococcal, and H. influenza vaccines
How to delivery ITP moms/delivery considerations/postnatal considerations
vaginal or cesarean
Avoid FSE and vacuums
No need to check fetal plt levels
Check cord plt, hold vit K and circ until plt level returns, nadir DOL 2-5
when/how to test for fetal–neonatal alloimmune thrombocytopenia
cases of otherwise unexplained fetal or neonatal thrombocytopenia, hemorrhage, or sono findings consistent with intracranial bleeding
HPA type and zygosity of both parents and the confirmation of maternal antiplatelet antibodies (with specificity for paternal (or fetal–neonatal) platelets and the incompatible antigen), via serology or genotyping. If paternal is heterozygote, can test fetus via CF-DNA or amnio
How to test fetal plt count in etal–neonatal alloimmune thrombocytopenia and risks
PUBS, 11% risk of serious complications
What is the obstetric management of fetal–neonatal alloimmune thrombocytopenia?
Delivery management?
IVIG with later addition of corticosteroids
Cordoscentesis no earlier than 32 weeks (in case emergency cesarean needed) to get plt level (can do plt tx but may worsen disease)
Recommend cesarean if plt <50K (but not contraindicated)
