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2010 Part XII: Hemostasis and Thrombosis Chapter 117: Thrombocytopenia 2011

was much more likely to increase platelet counts in patients with GESTATIONAL THROMBOCYTOPENIA
H. pylori infection than in uninfected patients, strengthening the case Gestational thrombocytopenia is detected in 5 to 7 percent of otherwise
315
for a causal relationship between infection and thrombocytopenia. On healthy pregnant women, accounting for 64 to 80 percent of patients
the other hand, eradication was shown to be less effective in patients with thrombocytopenia at term. 319–321 Gestational thrombocytopenia is
309
with severe thrombocytopenia. The recent ASH ITP guideline sug- a benign disorder and is not associated with an increased risk of bleed-
gests that ITP patients be screened for H. pylori and for eradication ing. Platelet counts are greater than 70 × 10 /L 316,317,319,320 and return to
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therapy to be used if testing is positive. 148
normal after delivery.
The pathogenesis of gestational thrombocytopenia is unknown.
Several mechanisms have been proposed, including hemodilution, a
THROMBOCYTOPENIA DURING compensated state of subclinical coagulopathy, endothelial cell injury,
PREGNANCY and immune destruction. Some authors have proposed platelet con-
sumption by the placenta and hormonal depression of megakaryo-
Thrombocytopenia is the second most common hematologic prob- poiesis as causes of gestational thrombocytopenia, as suggested by the
lem in pregnancy, after anemia. Table 117–6 lists the major causes rapid return of the platelet count to normal after delivery and by the
of thrombocytopenia in pregnancy (Chap. 7). Platelet counts tend transient normalization of the platelet count during pregnancy in some
to decrease during normal pregnancy, and mild thrombocytopenia cases of essential thrombocythemia. 321–324 Discriminating gestational
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(platelet counts ranging from 120 to 150 × 10 /L) occurs with mod- thrombocytopenia from ITP can be difficult because ITP is also com-
erate frequency, especially during the third trimester. 316,317 Bleeding mon in young women, and is often exacerbated by pregnancy. Neither
symptoms are generally mild, even in patients with severe thrombo- condition can be definitively diagnosed by currently available tests. The
cytopenia, probably because of the procoagulant state of pregnancy. diagnosis of ITP is favored if the patient had a previous episode of ITP
Nevertheless, it is important to investigate the cause of thrombocy- unassociated with pregnancy or if the thrombocytopenia is severe and
topenia and exclude the disorders associated with significant morbidity associated with bleeding that occurs in the first trimester. In healthy
such as eclampsia and hemolysis, elevated liver enzymes, low platelets pregnant women, a platelet count greater than 70 × 10 /L late in preg-
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(HELLP) syndrome (Table 117–6). A medical history should include nancy does not require intensive investigation, because bleeding is not
previous blood counts, history of other diseases, nutritional status, and likely in the woman or her newborn child. 325
intake of drugs and herbal supplements. It is important to be alert to
constitutional symptoms including fever, and, especially, weight loss;
neurologic abnormalities, arthritis, rash, and icterus. Key steps in the IMMUNE THROMBOCYTOPENIA
evaluation of thrombocytopenia in a pregnant woman include blood IN PREGNANCY
pressure measurement, evaluation of coagulation parameters, liver
and kidney function tests, and examination of the blood film. Physi- ITP is responsible for 4 to 5 percent of all cases of pregnancy-asso-
319,321
cal examination of the abdomen may be difficult in the third trimester ciated thrombocytopenia. Pregnancy itself may induce ITP, or
and abdominal ultrasound may be required to detect organomegaly. If exacerbate preexisting ITP, but generally the platelet count returns to
there are no suspicious clinical or laboratory findings, marrow aspira- the prepregnancy level after delivery. Diagnosis of ITP in a pregnant
tion is considered unnecessary. 317,318 woman requires the exclusion of other causes of thrombocytopenia as
in a nonpregnant woman, but also requires the evaluation of other preg-
nancy-related causes (see Table 117–6). However, the management of
ITP during pregnancy is different than in nonpregnant women. First,
TABLE 117–6. Causes of Thrombocytopenia During many of the drugs used to treat ITP may complicate pregnancy-related
Pregnancy problems such as gestational diabetes, hypertension, and psychiatric
disorders. Second, the fetus can also be affected by ITP and its treat-
Acute fatty liver of pregnancy ment. Antiplatelet antibodies can cross the placenta, decrease the fetal
320
Antiphospholipid syndrome and systemic lupus erythematosus platelet count, and sometimes cause bleeding. ITP drugs can affect
fetal development and growth, a fact to be considered in selecting ther-
Marrow disorders (e.g., aplastic anemia, acute leukemia)
apy during pregnancy. And third, all pregnancies will end with delivery
Disseminated intravascular coagulation of the baby, a process that may happen unexpectedly. Preparation for
Drugs (mostly heparins and antibiotics) delivery in a pregnant ITP patient requires close collaboration between
the hematologist, the obstetrician, and the neonatologist.
Gestational thrombocytopenia
In the management of pregnancy-related ITP, bleeding symp-
Hemolysis, elevated liver function tests, low platelets (HELLP) toms and platelet counts should be considered. 147,148 Although previous
syndrome guidelines have defined threshold platelet levels for treatment during
Hypersplenism pregnancy and labor, these numbers are arbitrary and not based on ran-
domized controlled studies. Generally, observation without therapy is
Immune thrombocytopenic purpura
appropriate if the platelet count is greater than 30 × 10 /L and the patient
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Nutritional deficiencies including folate deficiency has no bleeding symptoms. Therapy is required for a pregnant woman
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Preeclampsia, eclampsia who is bleeding, has a platelet count less than 20 × 10 /L in any trimes-
ter, or has a platelet count of 20 to 30 × 10 /L in the third trimester. 147,318
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Pseudothrombocytopenia Platelet counts should be increased to safe levels (generally >30 × 10 /L)
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Thrombotic thrombocytopenic purpura–hemolytic uremic if invasive procedures are planned. Glucocorticoids are the preferred
syndrome initial therapy for these patients. Because of their side effects, glucocorti-
Viral infections coids should be used at the minimal dose that will keep platelet counts in
a safe range. The recommended starting dose of prednisone is 10 mg/day,

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