Page 2199 - Hematology_ Basic Principles and Practice ( PDFDrive )

1946 Part XII Hemostasis and Thrombosis

Standardized Terminology and Definitions for Immune women can successfully be managed with less aggressive treatments.
TABLE Thrombocytopenia Proposed by the International Immunosuppressant medications, such as azathioprine, have been
131.2 Working Group (Vicenza Consensus Conference) used in pregnancy but should be reserved for refractory pregnancy-
in 2009 associated ITP with bleeding. There is a risk of severe thrombocyto-
penia in the newborn because of passive transfer of maternal
Terminology Definition antiplatelet autoantibodies. This can occur in 10% of newborns.
ITP Immune thrombocytopenia (rather than
idiopathic or immune Clinical and Laboratory Features
thrombocytopenic purpura)
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Platelet threshold for ITP <100 × 10 /L Thrombocytopenia
diagnosis
Primary ITP ITP with no associated cause (diagnosis Thrombocytopenia is the defining feature of ITP. The international
of exclusion) working group on standardization of terminology in ITP established
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Secondary ITP ITP in the setting of an underlying a platelet count below 100 × 10 /L as the cutoff for the diagnosis (see
3
cause such as drugs, HIV, or SLE Table 131.2). The rationale behind this threshold was that patients
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with mild thrombocytopenia (100–150 × 10 /L) have a low risk
Newly diagnosed ITP Designation for patients at diagnosis (approximately 7%) of developing persistent thrombocytopenia
(rather than “acute” ITP). (platelets less than 100 × 10 /L); platelet counts slightly below 150
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Persistent ITP Sustained or recurrent thrombocytopenia × 10 /L may be normal for certain ethnic groups; and mild throm-
lasting 3–12 months bocytopenia may be caused by physiologic processes, such as preg-
Chronic ITP Thrombocytopenia lasting >12 months nancy. Nonetheless, primary ITP remains a diagnosis of exclusion,
and as such, investigations are directed towards ruling out nonim-
Complete response Achievement of a platelet count of mune causes, including pseudothrombocytopenia, myelodysplastic
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≥100 × 10 /L in the absence of syndromes, thrombotic microangiopathies, splenomegaly, or heredi-
bleeding
tary thrombocytopenia; and secondary immune causes such as
Response Achievement of a platelet count of infection, concomitant autoimmune disease, or lymphoproliferative
≥30 × 10 /L and at least a twofold disorders.
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increase from baseline in the absence
of bleeding
Refractory ITP Failure to achieve a response or relapse Clinical Outcomes: Mortality, Bleeding and
a
after splenectomy and requirement Quality of Life
for treatment(s) to minimize the risk
of clinically significant bleeding Patients with ITP most commonly present with asymptomatic
thrombocytopenia. Although some patients bleed with platelet
a Splenectomy failure may not be applicable in children. 9
HIV, Human immunodeficiency virus; ITP, immune thrombocytopenia; counts less than 30 × 10 /L, many do not. Bleeding symptoms
SLE, systemic lupus erythematosus. characteristic of ITP (“platelet-type bleeding”) include skin bleeding
(i.e., bruises, nonpalpable purpura, or petechiae), oral hemorrhagic
blood blisters or oral petechiae, epistaxis, menorrhagia, or gastro-
eradication. Testing may be warranted in countries where H. pylori intestinal bleeding. The most severe complication is intracerebral
infection is endemic, particularly those where the response rates to hemorrhage (ICH).
eradiation therapy are high. In a systematic review of prospective studies, the incidence of ICH
ITP also may present for the first time or relapse in pregnancy. was 1.4% for adults (95% confidence interval [CI], 0.9–2.1) and
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Although mild ITP may be difficult to differentiate from incidental 0.4% for children (95% CI, 0.2–0.7). The proportion of patients
thrombocytopenia of pregnancy, pregnancy-related vascular disorders with severe (non-ICH) bleeding was 9.6% for adults (95% CI,
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must be excluded. Incidental thrombocytopenia of pregnancy (also 4.1–17.1) and 20.2% for children (95% CI, 10.0–32.9). Risk factors
called gestational thrombocytopenia) represents a physiologic change in for severe bleeding include severe thrombocytopenia, previous bleed-
platelet count. Pregnancy-related vascular disorders include pre- ing, and older age.
eclampsia, microangiopathy caused by HELLP syndrome (character- Chronic ITP has been associated with a risk of death that is up
ized by hemolysis, elevated liver enzymes, and a low platelet count), to four times higher than that in the general population. ITP patients
and acute fatty liver. Platelet counts tend to be mildly reduced and are more likely to die of bleeding, infection, and hematologic malig-
hypertension is common. nancies. Some deaths are attributable to adverse effects of treatment
Pregnancy-associated ITP may present early in pregnancy and rather than the disease. Quality of life is affected, at least in part,
thrombocytopenia can be severe. Typically, platelet counts increase because of the prevalence of fatigue that appears to be independent
after ITP-specific therapies such as IVIg or corticosteroids. In con- of platelet count levels.
trast, incidental thrombocytopenia of pregnancy, which occurs late
in pregnancy, is associated with a mild reduction in platelet count
and does not respond to immune-modulating therapy. Platelet count Investigations of Patients With Suspected Immune
thresholds for instituting treatment are the same as those for women Thrombocytopenia
with ITP who are not pregnant. In the absence of bleeding, treatment
should be considered when the platelet count decreases to less than Patients presenting with newly identified thrombocytopenia require
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20 × 10 /L. Vaginal deliveries are thought to be safe for mothers with a careful history and physical examination to uncover the underlying
ITP, even if the platelet count is very low, and most clinicians try to cause of the thrombocytopenia and to assess the risk of bleeding. A
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maintain the count above 20–30 × 10 /L. Epidural anesthesia is not complete blood count and review of the blood film is required (Fig.
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recommended with platelet counts below 70–80 × 10 /L; however, 131.1). HIV and HCV testing should be performed in any patient
this practice is operator driven and based on little evidence. IVIg and suspected of having ITP. There are insufficient data to support routine
corticosteroids are generally safe in pregnancy, but corticosteroids can screening for antinuclear antibodies or antiphospholipid antibodies
be associated with hypertension, gestational diabetes, intrauterine unless other signs and symptoms of systemic lupus erythematosus or
growth restriction, and other pregnancy-associated morbidities. antiphospholipid syndrome are present. BM aspiration and biopsy
Splenectomy is rarely performed during pregnancy because most should be reserved for patients with abnormalities affecting other cell