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2020-08-02T13:07:11Z

Common Causes

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2020-07-04T01:17:58Z

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== Definition ==

* Low platelet count in pregnancy, generally considered to be less than 100

== Pathophysiology ==

* Most commonly, thrombocytopenia of pregnancy is caused by dilution from increased plasma volume, similar to anemia in pregnancy, and is usually more noticeable in T2 and T3

== Etiology ==

* Gestational thrombocytopenia of pregnancy (70%)
* Hypertensive disorders (20%)
** Preeclampsia
** HELLP
* Immune disorders (5%)
** Immune-mediated thrombocytopenia (ITP)
** CAPS
** SLE
** Thrombotic microangiopathy: aHUS/TTP
* Other (5%)
** AFLP

== Epidemiology ==

* About 10% of pregnant women have platelets less than 150

== Investigations ==

* CBC and blood film
** Look for bicytopenia concerning for thrombotic microangiopathy
** Platelets <70 more consistent with ITP than gestational thrombocytopenia
* For ITP
** HIV, HBV, HCV
** Liver and thyroid tests
** Immunoglobulin levels
** DAT
** APLA and ANA
* Platelet antibody testing is useless

== Common Causes ==

{|
! Disease
! %
! Diagnostic Features
! Lab Findings
! Clinical Features
! Pathophys
! Comments
|-
| Gestational thrombocytopenia
| 5-9
| Onset 2nd-3rd trimester. Normal PLT previously. No neonatal thrombocytopenia.
| Plt >70
| Typically normal
| Unclear
| Diagnosis of exclusion. Resolves postpartum. No fetal thrombocytopenia.
|-
| ITP
| <1
| Onset any trimester. May see thrombocytopenia outside pregnancy.
| Plt <100 +/- large platelets
| May have bleeding, bruising, petechiae
| Antibody-mediated peripheral plt destruction with decrease thrombopoiesis.
| Diagnosis of exclusion. May be associated with fetal thrombocytopenia.
|-
| Preeclampsia
| 5-8
| Onset late 2nd or 3rd trimester (>20 weeks).
| Proteinuria >0.3 g/d
| BP ≥140/90
| Systemic endothelial dysfunction. Inadequate placentation.
| May precede other manifestations of preeclampsia. Can present postpartum.
|-
| HELLP
| <1
| 70% late 2nd or 3rd trimester, 30% postpartum.
| MAHA, high liver enzymes, high LDH.
| Signs of preeclampsia, but may be normotensive without proteinuria.
| Same as preeclampsia.
| Variant of preeclampsia.
|-
| AFLP
| <0.01
| Onset in 3rd trimester.
| Plt >50. High liver panel, creat, WBC, urate, ammonia. High PT/PTT, decreased fibrinogen. Hypoglycemia.
| RUQ pain. Jaundice, nausea/vomiting. Hepatic encephalopathy.
| Preeclampsia spectrum.
| MAHA not characteristic. Conjugated bili often high. Liver dysfunction greater than HELLP/preeclampsia.
|-
| TTP/aHUS
| <0.01
| Onset any trimester, but more common during 3rd or postpartum.
| MAHA, elevated creatinine, schostocytes on blood film.
| Fever, abdo pain, n/v, headache, vis changes, altered mental status.
| Congenital deficiency of ADAMTS13 (TTP) or complement dysregulation (aHUS).
| ADAMTS13 activity <5% in TTP. Liver panel and BP usually normal.
|}

== Management ==

* Depends on etiology
* Gestational thrombocytopenia
** No specific management
* ITP
** No need to treat until 36 weeks if platelets over 30
** If platelets < 30 or bleeding
*** Prednisone 0.25-1mg/kg) or IVIg (1g/kg ideally body weight, max 60mg)
** Monitor newborn for post-partum thrombocytopenia

== Prognosis ==

* In ITP, 25% of neonates will have thrombocytopenia and 10% will need treatment

[[Category:Hematology]]

Thrombocytopenia in pregnancy - Revision history

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