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Practice bulletins > #207 Thrombocytopenia and Pregnancy > Flashcards

#207 Thrombocytopenia and Pregnancy Flashcards

1
Q

What is the definition of thrombocytopenia?

A

Platelet count less than 150x10^9/L.

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2
Q

How many pregnant women are thrombocytopenic at the time of delivery?

A

7-12%

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3
Q

What are the most common manifestations of thrombocytopenia?

A

Petechiae, ecchymosis, epistaxis, gingival bleeding, and abnormal uterine bleeding (either heavy or intermenstrual)

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4
Q

What is the normal range of platelet count in non pregnant individuals?

A

165-415 x 10^9/L

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5
Q

What is the most common etiology of thrombocytopenia during pregnancy? Accounts for up to what % of cases?

A

Gestational thrombocytopenia, accounts for 80% of cases

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6
Q

What are causes of thrombocytopenia in pregnancy?

A

gestational thrombocytopenia, preeclampsia, HELLP syndrome, immune thrombocytopenia, pseudothrombocytopenia, viral infection, drug-induced thrombocytopenia, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, disseminated intravascular coagulation, systemic lupus erythematosus, antiphospholipid syndrome, and congenital thrombocytopenias

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7
Q

Gestational thrombocytopenia affects what % of pregannt women?

A

5-11%

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8
Q

What is thought to be the pathogenesis of gestational thrombocytopenia?

A

Uncertain, thought to be result of various processies, including hemodilution and enhanced clearance

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9
Q

What are the five key characteristics of gestational thrombocytopenia?

A
  1. Onset can occur at any point in pregnant, typically in mid-second to third trimester (most >75k)
  2. Women with gestational thrombocytopenia are asymptomatic with no hx of bleeding
  3. No hx thrombocytopenia outside of pregnancy
  4. Plts usually return to normal within 1-2 months after giving birth
  5. Incidence of fetal or neonatal thrombocytopenia in setting of gestational thrombocytopenia is low
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10
Q

What is the incidence of neonatal thrombocytopenia in women with gestational thrombocytopenia?

A

0.1-2.3%

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11
Q

HTN disorder of pregnancy is the etiology of thrombocytopenia in what % of cases of thrombocytopenia?

A

5-21%

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12
Q

Does preeclampsia affect platelet function?

A

Yes. Function may be impaired even if the platelet count is normal.

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13
Q

How do you diagnose immune thrombocytopenia?

A

Diagnosis of exclusion

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14
Q

What is the typical platelet count for immune thrombocytopenia?

A

Less than 100 x 10^9/L; median plt count at delivery 85-110 x 10^9/L

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15
Q

What is the definition of primary immune thrombocytopenia?

A

An acquired immune-mediated disorder characterized by isolated thrombocytopenia in the absence of any obvious initiating or underlying cause of thrombocytopenia.

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16
Q

What is the frequency of immune thrombocytopenia during pregnancy?

A

1 in 1,000-10,000 pregnancies

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17
Q

Does maternal immune thrombocytopenia affect the fetus?

A

Yes, it can. About 1/4 of infants born to women with ITP will develop plt counts <150k

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18
Q

What % of neonates born to women with immune thrombocytopenia will require treatment for thrombocytopenia?

A

8-15%

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19
Q

When do platelet counts of newborns with thrombocytopenia born to women with ITP nadir?

A

Typically nadir within first 2 weeks of life

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20
Q

What is fetal-neonatal alloimmune thrombocytopenia?

A

Platelet equivalent of Rh disease of newborn. Develops as a result of maternal alloimmunization to fetal platelet antigens with transplacental transfer of platelet-specific antibody and subsequent platelet destruction

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21
Q

How common is fetal-neonatal alloimmune thrombocytopenia?

A

1 in 1,000-3,000 live births

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22
Q

True or false, fetal-neonatal alloimmune thrombocytopenia can affect the first pregnancy?

A

True

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23
Q

How do you typically diagnose a patient with fetal-neonatal alloimmune thrombocytopenia?

A

Typically once neonate is born with evidence of profound thrombocytopenia. Pregnancy/labor course are indistinguishable from those of other low-risk ob patients. Can detect fetal intracranial hemorrhage in utero in one half of cases prior to onset of labor.

24
Q

How does an infant affected by fetal-neonatal alloimmune thrombocytopenia present?

A

Generalized petechiae or ecchymosis. Hemorrhage into viscera and bleeding after circumcision or venipuncture. Intracranial hemorrhage (15% of infants with plts <50k)

25
Q

What antigen is responsible for fetal-neonatal alloimmune thrombocytopenia?

A

Several polymorphic, diallelic antigen systems that reside on platelet membrane glycoproteins; more than 15 designated as different HPAs (eg HPA-1a)

26
Q

What is the work up for maternal thrombocytopenia?

A

detailed medical and family history and a physical examination, with attention to current medication use, blood pressure, splenomegaly, viral serology, and adjunctive laboratory studies as appropriate (CBC w/ peripheral smear)

27
Q

How does bone marrow biopsy help determine etiology of thrombocytopenia? Is it typically recommended as part of work up for thrombocytopenia in pregnancy?

A

Helps distinguish between inadequate platelet production and increased platelet turnover. Rarely necessary in evaluating a pregnant patient.

28
Q

What should be in your differential for a pregnant woman with sudden onset of significant maternal thrombocytopenia in 3rd trimester or postpartum period?

A

PEC, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, acute fatty liver, disseminated intravascular coagulation (ITP can present this way as well)

29
Q

If diagnosis of thrombocytopenia is made in antepartum period, how often should you check platelet count?

A

Based on expert opinion: check at each routine prenatal visit. Repeat 1-3 months after birth to check for resolution

30
Q

True or false, platelet transfusions in women with PEC are less effective than those without?

A

True. They have accelerated platelet destruction.

31
Q

What should your minimum platelet count be prior to cesarean section?

A

50 x 10^9/L

32
Q

Are corticosteroids or uterine curettage recommended for treatment of thrombocytopenia from SPEC or HELLP?

A

No differences noted in maternal mortality or morbidity. Although the thrombocytopenia may improve with these treatments.

33
Q

When should treatment for ITP during pregnancy be started?

A

Based on expert opinion: with symptomatic bleeding, plts <30k, or to increase plt count to a level considered safe for procedures.

34
Q

What is the first line treatment for maternal immune thrombocytopenia?

A

Corticosteroids or intravenous immunoglobulin or both. Expert opinion recommends corticosteroids as standard for courses up to 21 days

35
Q

What dose of prednisone should be given to pregnant patients with ITP? What is recommended dose in non pregnant adults?

A

Start at low dosage (10-20mg/day) then adjust to minimum dose that produces an adequate increase in plt count. In non preg 0.5-2mg/kg daily.

36
Q

How long after initiation of steroid treatment for ITP do you expect a response? When does it peak?

A

Initial response usually within 4-14 days. Peak response in 1-4 weeks.

37
Q

How do you dose intravenous immunoglobulin for ITP in pregnancy?

A

1g/kg as a one time dose, but may be repeated if necessary

38
Q

How long after IVIG treatment do you see a response in women with ITP? When is peak response?

A

Usually within 1-3 days. Peak within 2-7 days

39
Q

What is a management option for patients with ITP who fail first-line treatment (corticosteroids, IVIG)?

A

Splenectomy

40
Q

What is the only treatment for patients with TIP that provides prolonged remission at 1 year?

A

Splenectomy

41
Q

Is cesarean delivery safer than vaginal delivery for the fetus with maternal thrombocytopenia due to ITP?

A

No evidence to suggest so.

42
Q

What maternal tests or clinical characteristics can reliably predict the severity of thrombocytopenia in infants born to women with ITP?

A

None

43
Q

Is routine intrapartum fetal platelet counts recommended in pregnancies complicated by ITP?

A

No

44
Q

What is the risk of fetal loss per cordocentesis procedure?

A

0.6-1.3%

45
Q

What is appropriate neonatal care for infants born of pregnancies complicated by ITP?

A

Send off umbilical cord blood platelet count at delivery. Defer IM injections or elective procedures pending plt count. Observe clinically as plt counts reach nadir between 2-5 days after birth

46
Q

Is low dose aspirin a contraindication to neuraxial blockade?

A

No

47
Q

What is the risk of epidural hematoma from neuraxial anesthetics in patietnw ith plt count >70k?

A

<0.2%

48
Q

What should prompt you to looks for fetal-neonatal alloimmune thrombocytopenia?

A

In cases of otherwise unexplained fetal or neonatal thrombocytopenia, hemorrhage, or ultrasonographic findings c/w intracranial bleeding

49
Q

How do you diagnose fetal-neonatal alloimmune thrombocytopenia?

A

Determination of HPA type and zygosity of both parents and the confirmation of maternal antiplatelet antibodies with specificity for paternal (or fetal) plts and the incompatible antigen

50
Q

How can you determine the fetal platelet count in pregnancies c/b fetal-neonatal alloimmune thrombocytopenia?

A

No adequate indirect methods, need to do umbilical cord blood sampling

51
Q

Serious complications occus in what % of fetal blood sampling procedures in the setting of fetal-neonatal alloimmune thrombocytopenia?

A

In 11% (such as emergent preterm cesarean delivery)

52
Q

At how many weeks should you do umbilical cord blood sampling in fetus with fetal-neonatal alloimmune thrombocytopenia? Why?

A

At 32 weeks. Close enough to delivery to give idea if vaginal delivery is safe (document plt count), late enough in preg to deliver viable newborn if any complications result in emergent delivery

53
Q

How do you treat fetal-neonatal alloimmune thrombocytopenia prenatally?

A

Empiric initiation of therapy (IVIG with later addition of oral prednisone)

54
Q

At what fetal platelet count does recommendation for mode of delivery change?

A

<50k, cesarean section recommended

55
Q

Does ITP confer a high risk of neonatal hemorrhage?

A

Very low risk

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