207 - Thrombocytopenia in Pregnancy

Question 1

Normal plt count outside pregnancy

Answer 1

165-415K

Question 2

Thrombocytopenia in pregnancy

Answer 2

<150K

Question 3

Causes of thrombocytopenia in pregnancy

Answer 3

Question 4

Prevalence of gestational thrombocytopenia

Answer 4

5-11%

Question 5

Theorized contributors to gestational thrombocytopenia

Answer 5

Hemodilution and increased clearance

Question 6

5 key components of gestational thrombocytopenia

Answer 6

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%)

Question 7

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

Answer 7

14

Question 8

What % of thrombocytopenia in pregnancy is caused by hypertensive disorders?

Answer 8

5-21%

Question 9

impact of hypertensive disorders on platelets

Answer 9

not sures, but:

1) incresed activation/consuption
2) decreased function

* thrombocytopenia may be a first sign of impending hypertensive disorder

Question 10

Risk of neonatal thrombocytopenia in women with hypertensive disorders

Answer 10

1.8%, but unclear if due to maternal disease or to underlying IUGR and prematurity

Question 11

Maternal immune thrombocytopenia - Definition

Answer 11

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

Question 12

Maternal immune thrombocytopenia - Causes

Answer 12

Primary: immune

Secondary: APLS, SLE, HIV, HepC, CMV, H. pylori, drugs (heparins, antimicrobials, anticonvulsants, analgesics),

Question 13

Maternal immune thrombocytopenia - Frequency in pregnancy

Answer 13

1/1’000-1/10’000 pregnancies

Question 14

Definition of severe ITP, and symptoms

Answer 14

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)

Question 15

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?

Answer 15

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

Question 16

What is fetal-neonatal alloimmune thrombocytopenia?

Answer 16

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)

Question 17

What is the prevalence of fetal-neonatal alloimmune thrombocytopenia

Answer 17

1/1000-1/3000

Question 18

T/F: fetal–neonatal alloimmune thrombocytopenia can affect a first pregnancy

What is the prognosis of next pregnancy

Answer 18

TRUE! may be life-threatening

Next pregnancy not necessarily worse

Question 19

Presentation of mom and fetus/neonate affected by fetal–neonatal alloimmune thrombocytopenia

Answer 19

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)

Question 20

Antigen that causes the most severe fetal-neonatal alloimmune thrombocytopenia? (also the most common in white patients)

Answer 20

human platelet antigen-1a

(HPA-1a)

Question 21

MCC of thrombocytopenia by trimester:

Answer 21

1st: ITP
2nd: Gestational thrombocytopenia

3rd/PP: preeclampsia, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, acute fatty liver, or disseminated intravascular coagulation. May be ITP

Question 22

Workup of thrombocytopenia in pregnancy?

Answer 22

CBC and smear

Question 23

Management of gestational thrombocytopenia in pregnancy

Answer 23

Once diagnosed repeat plt count at each prenatal visit

Repeat platelet count 1-3months PP

Question 24

At what plt level to transfuse platelets

Answer 24

<70K for epidural

<50K if undergoing major surgery (cesarean)

<30K or symptomatic bleeding

Question 25

Steroids and thrombocytopenia of hypertensive disorders?

Answer 25

May increase lab value but does not change outcomes

Question 26

Treatment of ITP in pregnancy including dosage, response time, and peak response time

Answer 26

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

Question 27

Effect of medical treatment of ITP on fetus plt levels and outcomes

Answer 27

No reliable effect on plt count or outcomes

Question 28

Special treatment for ITP patients in pregnancy

Answer 28

CBC q trimester if asymptomatic/remission, more if throbocytopenic

Avoid NSAIDs, Salicylates, trauma

if s/p splenectomy give meningococcal, pneumococcal, and H. influenza vaccines

Question 29

How to delivery ITP moms/delivery considerations/postnatal considerations

Answer 29

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

Question 30

when/how to test for fetal–neonatal alloimmune thrombocytopenia

Answer 30

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

Question 31

How to test fetal plt count in etal–neonatal alloimmune thrombocytopenia and risks

Answer 31

PUBS, 11% risk of serious complications

Question 32

What is the obstetric management of fetal–neonatal alloimmune thrombocytopenia?

Delivery management?

Answer 32

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)