Management of neonatal thrombocytopenia in a context of maternal antiplatelet alloimmunization: Expert opinion of the French-speaking working group

Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a potentially devastating disease, seen in 1/800-1000 neonates. FNAIT is the most common cause of early-onset isolated severe neonatal thrombocytopenia in maternity wards. The most feared complication of this disorder is intracranial hemorrhage, leading to death or neurological sequelae. There is no systematic screening of at-risk pregnancies and FNAIT is often discovered when fetal or neonatal bleeding is observed. A working group on fetomaternal platelet alloimmunization was created in 2017, under the auspices on the French Group of Thrombosis and Hemostasis (GFHT). The first objective of this group was to survey clinical practices for treatment of thrombocytopenic neonates in a context of suspected or confirmed FNAIT.

Thrombocytopenia during pregnancy

Thrombocytopenia is observed in 6 to 15% of pregnant women at the end of pregnancy, and is usually moderate. Gestational thrombocytopenia (defined as a mild thrombocytopenia, occurring during the 3rd trimester with spontaneous resolution postpartum and no neonatal thrombocytopenia) is the most common cause of thrombocytopenia during pregnancy but a low platelet can also be associated with several diseases, either pregnancy specific or not, such as preeclampsia, HELLP syndrome, or idiopathic thrombocytopenic purpura (ITP). The differential diagnosis between ITP and gestational thrombocytopenia is clinically important with regard to the fetus, due to the risk of neonatal thrombocytopenia. However, this differential diagnosis is very difficult during pregnancy.

Thrombocytopenia which need to be investigated are the following: thrombocytopenia known before pregnancy, thrombocytopenia occurring during the 1st and 2nd trimester, platelet count < 75 G/l in the 3rd trimester or thrombocytopenia in case of pregnancy with complications. Investigations have to be discussed in function of history and clinical examination, gestational age and severity of thrombocytopenia.

No treatment is required in case of gestational thrombocytopenia. There are few data to distinguish management of ITP between pregnant and non-pregnant women but management is different because of the potential adverse effects of the treatment for the woman and/or the fetus, the requirement for a good hemostasis at delivery and the risk of neonatal hemorrhage. One important problem is that it is not possible to predict the risk of neonatal thrombocytopenia in babies born from women with ITP.

Treatment options for severe pulmonary embolism during pregnancy and the postpartum period: a systematic review

Essentials The evidence on how to manage life-threatening pregnancy-related pulmonary embolism (PE) is scarce. We systematically reviewed all available cases of (sub)massive PE until December 2016. Thrombolysis in such severe PE was associated with a high maternal survival (94%). The major bleeding risk was much greater in the postpartum (58%) than antepartum period (18%).

SUMMARY

Background Massive pulmonary embolism (PE) during pregnancy or the postpartum period is a rare but dramatic event. Our aim was to systematically review the evidence to guide its management. Methods We searched Pubmed, Embase, conference proceedings and the RIETE registry for published cases of severe (submassive/massive) PE treated with thrombolysis, percutaneous or surgical thrombectomy and/or extracorporeal membrane oxygenation (ECMO), occurring during pregnancy or within 6 weeks of delivery. Main outcomes were maternal survival and major bleeding, premature delivery, and fetal survival and bleeding. Results We found 127 cases of severe PE (at least 83% massive; 23% with cardiac arrest) treated with at least one modality. Among 83 women with thrombolysis, survival was 94% (95% CI, 86-98). The risk of major bleeding was 17.5% during pregnancy and 58.3% in the postpartum period, mainly because of severe postpartum hemorrhages. Fetal deaths possibly related to PE or its treatment occurred in 12.0% of cases treated during pregnancy. Among 36 women with surgical thrombectomy, maternal survival and risk of major bleeding were 86.1% (95% CI, 71-95) and 20.0%, with fetal deaths possibly related to surgery in 20.0%. About half of severe postpartum PEs occurred within 24 h of delivery. Conclusions Published cases of thrombolysis for massive PE during pregnancy and the postpartum period suggest a high maternal and fetal survival (94% and 88%). In the postpartum period, given the high risk of major bleeding with thrombolysis, other therapeutic options (catheter [or surgical] thrombectomy, ECMO) may be considered if available.

Pre-pregnancy BMI, delivery BMI, gestational weight gain and the risk of postpartum venous thrombosis

OBJECTIVE

To characterize the risk of postpartum venous thromboembolism (VTE) associated with body-mass-index (BMI) in both pre-pregnancy and at delivery, and with gestational weight gain (GWG).

METHODS

In a population-based, case-control study, we identified all women in Washington State with ICD-9 codes for VTE in the postpartum period between 2003 and 2011. Controls were women without VTE in the postpartum period, matched by delivery year to cases. Pre-pregnancy BMI, delivery BMI, and covariates were abstracted from birth certificates. Adjusted logistic regression models separately estimated postpartum VTE risk associated with categories of BMI in pre-pregnancy and at delivery.

RESULTS

Cases (n=289) had a higher mean BMI than controls (n=4208) pre-pregnancy (29.9kg/m(2) and 26.3kg/m(2), respectively) and at delivery (34.8kg/m(2) vs. 31.4kg/m(2), respectively), with similar gestational weight gains. Compared with women with a normal pre-pregnancy BMI (18.5-24.9kg/m(2)), overweight (BMI 25-29.9kg/m(2)) and obese (BMI≥30kg/m(2)) women were at a 1.5-fold and 1.8-4 fold greater risk of postpartum VTE, respectively, with greatest risks in women with class III obesity (BMI≥40kg/m(2): OR 4.0, 95%CI 2.7-6.3). Observed associations of delivery BMI with postpartum VTE were less strong than those of pre-pregnancy BMI. Large weight gains during pregnancy (>22kg) also contributed to greater VTE risks (OR 1.5, 95%CI 1.0-2.2).

CONCLUSION

Maternal BMI is an important risk factor for postpartum VTE, grading from weak in overweight women to very strong in women with class III obesity. Care providers may prefer to use pre-pregnancy BMI, along gestational weight gain, when stratifying the risk of postpartum VTE at delivery.

Recombinant human FVIIa for reducing the need for invasive second-line therapies in severe refractory postpartum hemorrhage: a multicenter, randomized, open controlled trial

BACKGROUND

Case reports on recombinant human factor VIIa (rhuFVIIa) use in women with severe postpartum hemorrhage (PPH) showed encouraging results, but no randomized controlled trial (RCT) is available.

PATIENTS AND METHODS

Eighty-four women with severe PPH unresponsive to uterotonics were randomized to receive one early single rhuFVIIa infusion (n = 42) or standard care (no rhuFVIIa; n = 42). The primary efficacy outcome measure was the reduction of the need for specific second-line therapies, such as interventional hemostatic procedures, for blood loss and transfusions. The primary safety outcome measure was the number of deaths and thrombotic events during the 5 days following rhuFVIIa infusion.

RESULTS

rhuFVIIa was associated with a reduction in the number of patients who needed second-line therapies compared with controls (standard care). Specifically, 39/42 (93%) patients in the standard care arm received second-line therapies and 22/42 (52%) patients in the rhuFVIIa arm (absolute difference, 41%; range, 18-63%; relative risk RR, 0.56 [0.42-0.76]). The delivery mode (vaginal or Cesarean section) did not affect the primary outcome. No death occurred. Two venous thrombotic events were recorded in the rhuFVIIa arm: one ovarian vein thrombosis and one deep vein thrombosis with a non-severe pulmonary embolism.

CONCLUSION

This open RCT in women with severe PPH refractory to uterotonics shows that rhuFVIIa reduces the need for specific second-line therapies in about one in three patients, with the occurrence of non-fatal venous thrombotic events in one in 20 patients.

Racial and ethnic differences in the risk of postpartum venous thromboembolism: a population-based, case-control study

BACKGROUND

Venous thromboembolism (VTE) is a major contributor of maternal morbidity and mortality. Whether maternal race/ethnicity is associated with the risk of postpartum VTE remains unclear.

METHODS AND RESULTS

We conducted a population-based, case-control study in Washington State, from 1987 through 2011. Cases comprised all women with selected International Classification of Diseases, Ninth Edition, Clinical Modification codes for hospitalized VTE within 3 months post-delivery. Controls were randomly selected postpartum women who did not experience a VTE. Characteristics of women and their deliveries were abstracted from birth certificates. Using logistic regression models, we compared the risk of postpartum VTE in black, Asian, and Hispanic women with that in non-Hispanic white women, after adjustment for maternal characteristics (age, body mass index, parity, education), pregnancy complications, and delivery methods.

RESULTS

Our study comprised 688 cases and 10 246 controls. Among controls, the mean age and body mass index were 27.5 years and 26.3 kg m(-2) , respectively. Compared with white women, black and Asian women had a greater and lower risk of postpartum VTE (adjusted odds ratio [OR] 1.50, 95% confidence interval [CI] 1.10-2.04 and OR 0.67, 95%CI 0.48-0.94, respectively). A lower risk was present in Hispanic women (adjusted OR 0.80, 95% CI 0.61-1.06) but was not statistically significant. In subgroup analyses, we observed an increased risk for black compared with white women among women who delivered via cesarean section (OR 2.03, 95% CI 1.34-3.07) but not among vaginal deliveries (OR 1.03, 95% CI 0.61-1.74).

CONCLUSIONS

Maternal race/ethnicity is associated with the risk of postpartum VTE, independently of other risk factors, and should be considered when assessing the use of thromboprophylaxis after delivery.

NF-κB is activated from endosomal compartments in antiphospholipid antibodies-treated human monocytes

BACKGROUND

The antiphospholipid antibody syndrome (APS) is an autoimmune disease associated with arterial or venous thrombosis and/or recurrent fetal loss and is caused by pathogenic antiphospholipid antibodies (aPLA). We recently demonstrated that Toll-like receptor 2 (TLR2) and CD14 contribute to monocyte activation of aPLA.

OBJECTIVE

To study the mechanisms of cell activation by aPLA, leading to pro-coagulant and pro-inflammatory responses.

METHODS AND RESULTS

For this study, we used purified antibodies from the plasmas of 10 different patients with APS and healthy donors. We demonstrate that aPLA, but not control IgG, co-localizes with TLR2 and TLR1 or TLR6 on human monocytes. Blocking antibodies to TLR2, TLR1 or TLR6, but not to TLR4, decreased TNF and tissue factor (TF) responses to aPLA. Pharmacological and siRNA approaches revealed the importance of the clathrin/dynamin-dependent endocytic pathway in cell activation by aPLA. In addition, soluble aPLA induced NF-κB activation, while bead-immobilized aPLA beads, which cannot be internalized, were unable to activate NF-κB. Internalization of aPLA in monocytes and NF-κB activation were dependent on the presence of CD14.

CONCLUSION

We show that TLR2 and its co-receptors, TLR1 and TLR6, contribute to the pathogenicity of aPLA, that aPLA are internalized via clathrin- and CD14-dependent endocytosis and that endocytosis is required for NF-κB activation. Our results contribute to a better understanding of the APS and provide a possible therapeutic approach.

[Thrombotic risk in myeloproliferative neoplasms: what the general practitioner needs to know]

Polycythaemia vera, essential thrombocythemia and primary myelofibrosis are stem cell-derived clonal haemopathies classified in the group of myeloproliferative neoplasms. Their clinical course may be complicated by both arterial and venous (sometimes in unusual sites) thrombotic events. Although general risk factors contribute to the prevalence of thrombotic events in this population, some other risk factors are specifically associated with the myeloproliferative neoplasms. The treatment options are aspirin, anticoagulation, cytoreduction and phlebotomies.

[New oral anticoagulants: from theory to practice]

Physicians are confronted with many new antithrombotic drugs, either antiplatelet agents or new oral anticoagulants (NOAC). Targets of NOAC are specific (either anti-IIa or antiXa) and clinical studies have shown that NOAC are as efficacious and as safe as "old" anticoagulants (heparin, low molecular weight heparin, vitamin K antagonists); moreover they present some advantages. Indeed, NOAC have a wide therapeutic window and do not require laboratory monitoring. Therefore, it is very tempting to prescribe them on a large scale basis in patients at risk or having thromboembolic diseases. However, things are not so simple in the day-to-day practice and this review aims at answering in a brief and simplified manner to some questions.

Identification and weighting of the most critical "real-life" drug-drug interactions with acenocoumarol in a tertiary care hospital

PURPOSE

The objective of this study was to identify the most clinically relevant drug-drug interactions (DDIs) at risk of affecting acenocoumarol safety in our tertiary care university hospital, a 2,000 bed institution.

METHODS

We identified DDIs occurring with acenocoumarol by combining two different sources of information: a 1-year retrospective analysis of acenocoumarol prescriptions and comedications from our Computerized Physician Order Entry (CPOE) system (n = 2,439 hospitalizations) and a retrospective study of clinical pharmacology consultations involving acenocoumarol over the past 14 years (1994-2007) (n = 407). We classified these DDIs using an original risk-analysis method. A criticality index was calculated for each associated drug by multiplying three scores based on mechanism of interaction, involvement in a supratherapeutic international normalized ratio (INR) (≥ 6) and involvement in a severe bleeding.

RESULTS

One hundred and twenty-six DDIs were identified and weighted. Twenty-eight drugs had a criticality index ≥ 20 and were therefore considered at high risk for interacting with acenocoumarol by increasing its effect: 75% of these drugs involved a pharmacokinetic mechanism and 14 % a pharmacodynamic mechanism. An unknown mechanism of interaction was involved in 11 % of drugs.

CONCLUSION

Twenty-eight specific drugs were identified as being at high risk for interacting with acenocoumarol in our hospital using an original risk-analysis method. Most analyzed drugs interact with acenocoumarol via a pharmacokinetic mechanism. Actions such as the implementation of alerts in our CPOE system should be specifically developed for these drugs.

Eculizumab in acute recurrence of thrombotic microangiopathy after renal transplantation

Renal thrombotic microangiopathy (TMA) is a severe complication of systemic lupus erythematosus (SLE), which is associated with the presence of antiphospholipid (aPL) antibodies. In its most fulminant form, TMA leads to a rapid and irreversible end-stage renal failure. Eculizumab, an anti-C5 monoclonal antibody, is a novel therapy of choice for patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome. Here, we report the case of a 27-year-old woman, known for SLE and end-stage renal disease due to fulminant TMA. Both aPL antibodies and antinucleosome antibodies were positive. The patient underwent a living-related kidney transplantation with immediate production of urine. Although serum creatinine was remaining high, a graft biopsy, performed on day 6, demonstrated a TMA recurrence. Despite a treatment with plasma exchange, the situation got worse and dialysis was started. Eculizumab treatment was subsequently administered and renal function improved rapidly. Three months after transplantation, serum creatinine was at 100 μmol/L, without proteinuria. This case illustrates the benefit of eculizumab therapy in a fulminant recurrence of TMA after kidney transplantation, resistant to classical therapy.

[Update on new antithrombotic treatments]

Update on new antithrombotic treatments Antithrombotic treatments are frequently prescribed in different clinical situations. Classical anticoagulants have some disadvantages. New anticoagulants have emerged recently. Fondaparinux is now prescribed for both prophylaxis and treatment of venous thromboembolism. Two drugs are particularly interesting: rivaroxaban and dabigatran. Concerning the new antiplatelet agents, many molecules such as prasugrel, ticagrelor, cangrelor, SCH530348 or terutroban have appeared recently. They are directed either to the P2Y12 receptor or to other original targets. Studies have shown an increased bleeding risk for some of them as well as unexpected side effects. In the next future, these new molecules could allow a more individualised prescription of antithrombotic agents.

The association between circulating antibodies against domain I of beta2-glycoprotein I and thrombosis: an international multicenter study

BACKGROUND

Diagnosis of the antiphospholipid syndrome (APS) is difficult as a result of limited specificity of existing assays for detecting clinically relevant antiphospholipid antibodies. Anti-beta2-glycoprotein I (beta 2GPI) antibodies play a central role in the disease process of APS.

OBJECTIVES

We have investigated the relation between antiphospholipid antibodies with specificity for domain I of beta 2GPI and thrombosis/pregnancy morbidity in an international multicenter study.

PATIENTS/METHODS

Four hundred and seventy-seven patients derived from nine different centres met the inclusion criterion of having anti-beta 2GPI antibodies in their plasma/serum. Clinical data and results of tests for lupus anticoagulant, anti-cardiolipin antibodies and anti-beta 2GPI antibodies were established at the different centres of inclusion. After being re-tested for the presence of IgG and/or IgM anti-beta 2GPI antibodies, the samples were tested for the presence of IgG-directed against domain I of beta 2GPI and results were correlated with the thrombotic and obstetric history.

RESULTS

Re-testing for the presence of anti-beta 2GPI antibodies resulted in inclusion of 442/477 patients. IgG class anti-domain I antibodies were present in plasma of 243/442 patients (55%). 201/243 (83%) had a history of thrombosis. This resulted in an odds ratio of 3.5 (2.3-5.4, 95% confidence interval) for thrombosis. Anti-domain I IgG antibodies were also significantly correlated with obstetric complications [odds ratio: 2.4 (1.4-4.3, 95% confidence interval)].

CONCLUSION

In this multicenter study, the detection of IgG antibodies that are directed against domain I of beta 2GPI proved to be more strongly associated with thrombosis and obstetric complications than those detected using the standard anti-beta 2GPI antibody assay.

[Advantages of capillary INR monitoring for oral anticoagulation]

More and more patients are treated with long term oral anticoagulation. The time spent in therapeutic range is often limited since many factors affect INR. Too high or too low INRs increase respectively the hemorrhagic or thromboembolic risks. INR monitoring by a capillary device either in autonomy (self-management) by some selected patients or in relation with the treating physician (self-control), allows increasing the time spent in therapeutic range. Capillary INR monitoring can also be made at the medical office: it is less invasive and provides a quicker answer than a venous INR.

Impending paradoxical embolism. When and how to treat?

Impending paradoxical embolism (IPDE) is the presence of an entrapped thrombus through the patent foramen ovale (PFO). Usually IPDE are diagnosed by echocardiography or thoracic CT-scan performed during the evaluation of patient presenting with a suspicion of pulmonary embolism (PE). We report the case of a 73-year-old patient presenting with a very large IPDE successfully treated with cardiac surgery and we focus our discussion on the treatment modalities of this rare entity (anticoagulation alone, fibrinolytic regimens, cardiac surgery, percutaneous thrombectomy) and on PFO management after IPDE.

[Diagnosis and management of mild bleeding disorders]

Although mild bleeding disorders are still poorly defined, they are clinically important since they may be associated with serious hemorrhagic complications during trauma or surgical procedures. These disorders are mainly related to dysfunction of primary or secondary hemostasis. Standardized questionnaires may be of some help in identifying patients who deserve further biological evaluation. Several pharmacological agents are available; however, before prophylactic administration of such drugs, a trade-off between their thrombotic risks and excessive bleeding should be made.

[Von Willebrand disease: a common and unrecognized bleeding disorder]

The von Willebrand factor plays an important role in primary and secondary hemostasis. Von Willebrand disease is due to a quantitative or qualitative abnormality of von Willebrand factor. It is the most frequent constitutional abnormality of hemostasis. The main manifestation of von Willebrand disease is a mucocutaneous hemorrhagic syndrome; however, von Willebrand disease is characterized by an important clinical and biological heterogeneity. Its transmission is autosomal, usually dominant. A screening can be made by a general practitioner on the basis of a good clinical history. It is then important to confirm the diagnosis in a specialized laboratory because an adequate treatment can be prescribed to avoid hemorrhagic complications, in particular at the time of surgical procedures.

[Inherited thrombophilia and arterial diseases]

Thrombophilia may be defined as an acquired or congenital abnormality of hemostasis predisposing to thrombosis. Some of the inherited abnormalities such as factor V Leiden mutation, factor II G20210A mutation as well as deficiencies in antithrombin, protein C and protein S, are already known to be risk factors for venous thromboembolism. This review focuses on the link between these abnormalities and arterial thrombosis. Routine screening for these disorders is not indicated in most cases of arterial complications, but could be useful in some sub-groups of patients, such as young patients, smokers, patients on oral contraception, or those with premature occlusion after revascularization procedures. Anticoagulation rather than antiplatelet therapy may be preferable for these patients.

[Anticoagulation in patients with chronic renal failure]

Anticoagulation may be difficult to implement in patients suffering from chronic renal failure on account of platelet disorders and impaired clearance of some anticoagulant drugs. Although no adjustment of heparin and coumarin dosage is necessary, more frequent testing of coagulation pathways may be required when these drugs are used in patients with renal failure. Long-term use of LMWH should be implemented cautiously with regular testing of anti-factor Xa activity and a half-dose may be advocated in patients with a creatinine clearance < 30 ml/mn. Danaparoid and thrombin inhibitors should be used mainly in patients suffering from renal failure and heparin-induced thrombocytopenia with regular monitoring of coagulation tests.

Thrombocytopenia during pregnancy. Importance, diagnosis and management

Thrombocytopenia is observed in 6 to 15% of pregnant women at the end of pregnancy, and is usually moderate. Gestational thrombocytopenia (defined as a mild thrombocytopenia, occurring during the 3 rd trimester with spontaneous resolution postpartum and no neonatal thrombocytopenia) is the most common cause of thrombocytopenia during pregnancy but a low platelet can also be associated with several diseases, either pregnancy specific or not, such as preeclampsia, HELLP syndrome, or idiopathic thrombocytopenic purpura (ITP). The differential diagnosis between ITP and gestational thrombocytopenia is clinically important with regard to the fetus, due to the risk of neonatal thrombocytopenia. However, this differential diagnosis is very difficult during pregnancy. Thrombocytopenia which need to be investigated are the following: thrombocytopenia known before pregnancy, thrombocytopenia occurring during the 1(st) and 2(nd) trimester, platelet count <75 G/l in the 3(rd) trimester or thrombocytopenia in case of pregnancy with complications. Investigations have to be discussed in function of history and clinical examination, gestational age and severity of thrombocytopenia. No treatment is required in case of gestational thrombocytopenia. There are few data to distinguish management of ITP between pregnant and non-pregnant women but management is different because of the potential adverse effects of the treatment for the woman and/or the fetus, the requirement for a good hemostasis at delivery and the risk of neonatal hemorrhage. One important problem is that it is not possible to predict the risk of neonatal thrombocytopenia in babies born from women with ITP.

Not all statins interfere with clopidogrel during antiplatelet therapy

BACKGROUND

Clopidogrel and statins are frequently coadministered in patients with ischemic heart diseases. Recent reports suggested that clopidogrel's effectiveness in inhibiting adenosine diphosphate (ADP)-induced platelets aggregation is attenuated by co-administration of certain statins. The objective of the present study was to define which statin might interfere with the antiaggregation property of clopidogrel.

METHODS

We designed a pharmacokinetic study and tested ex vivo platelet function on 21 healthy volunteers who received clopidogrel and all currently commercially available statins: rosuvastatin [10 mg o.d.], simvastatin [20 mg o.d.], fluvastatin [80 mg o.d.], pravastatin [40 mg o.d.], and atorvastatin [20 mg o.d.]. Each statin was administered for 7 days followed by 1 week of wash-out period with clopidogrel treatment alone. Detection of the statins in the plasma was performed on all blood samples, using HPLC analytical method.

RESULTS

All individuals, except one, were responders to clopidogrel with inhibition of ex vivo ADP induced platelet aggregation. All statins, except pravastatin, were detectable in the plasma at the end of each treatment period in all patients, and no statin was detectable after any of the wash-out periods. Clopidogrel was significantly less efficient to prevent platelet aggregation when coadministrated with simvastatin or fluvastatin. No difference was observed in clopidogrel efficacy when coadministered with rosuvastatin, pravastatin or atorvastatin.

CONCLUSIONS

This is the first study investigating clopidogrel-statin interactions on ex vivo platelet function with all commercially available statins and which were administered to the same individuals. It demonstrates in healthy volunteers that at the doses used in this study, simvastatin and fluvastatin, but not atorvastatin, pravastatin or rosuvastatin interfere with the anti-aggregation effect of clopidogrel.

Anti-protein S antibodies following a varicella infection: detection, characterization and influence on thrombin generation

Postinfectious purpura fulminans is a rare disease. Varicella is one of the precipitating conditions and we recently observed such a case. The 4-year-old child was found to have a severe transient protein S deficiency. By enzyme-linked immunosorbent assay and surface plasmon resonance we first demonstrated that anti-protein S antibodies were present and also transient. Next we characterized the epitopes against which these antibodies were directed and found that they predominantly recognized the N-terminal part of protein S. Finally we showed by thrombography a transient dramatic hypercoagulable state as a result of thrombin being unregulated by the dynamic protein C inhibitory system: in vitro thrombin generation, in response to a low concentration of tissue factor, was almost insensitive to activated protein C up to 25 nmol L(-1) on day 4 while it was normally sensitive on day 42. For the first time, we demonstrated a temporal relationship between protein S deficiency, antibodies to protein S and hypercoagulability, thus supporting the pathogenic role of these antibodies.

D-dimer levels during delivery and the postpartum

BACKGROUND

D-dimer (DD) measurement has proved to be very useful to exclude venous thromboembolism (VTE) in outpatients. However, during pregnancy, the progressive increase as well as the interindividual variations of DD means that in this instance they are of poor value to rule out VTE. Only a few studies have reported measurements of DD levels in the postpartum.

OBJECTIVES

To measure DD sequentially in the puerperium in order to determine when DD levels return to values obtained in non-pregnant women and can again be used in the exclusion of VTE.

PATIENTS AND METHODS

After uncomplicated pregnancies, 150 women delivering at term either vaginally (n = 100) or by cesarean section (n = 50) were included. DD levels were measured immediately following delivery and next at days 1, 3, 10, 30 and 45.

RESULTS

There was a marked elevation of DD at delivery, especially when instrumental. All DD measurements were above 500 ng mL(-1) at delivery, at day 1 and at day 3 postpartum. A sharp decrease in DD was observed between day 1 and day 3, followed by a slight increase at day 10. At day 30 and day 45, respectively, 79% and 93% of women in the vaginal delivery group and 70% and 83% in the cesarean group had levels below 500 ng mL(-1). Bleeding, breastfeeding and heparin prophylaxis did not modify DD levels significantly.

CONCLUSION

Using the Vidas DD new assay, our study provides reference intervals for DD in the postpartum period. Using a cut-off at 500 ng mL(-1), DD measurement for ruling out VTE was found to be useful again 4 weeks after delivery.

[Changes in D-dimer levels during pregnancy and the postpartum period: results of two studies]

In outpatients D-dimer (DD) measurement is included in most algorithms to exclude venous thromboembolism (VTE). We have recently performed two studies to evaluate the evolution of DD during pregnancy and the postpartum. During pregnancy, DD increase progressively and are of poor value to exclude VTE after 20 weeks of gestation. During labour, DD are usually very high and decrease quickly during the first 3 days post-delivery. Many weeks are necessary to obtain their normalisation and therefore their utility to rule out VTE is very limited until 4 weeks postpartum. This increase of DD values until 4 to 6 weeks after delivery correlates with the length of antithrombotic prophylaxis recommended for women at high risk of VTE.

[Menorrhagia and hemostatic abnormalities: diagnosis and treatment]

Menorrhagias consisting of heavy menstrual bleeding are a common complaint, encountered in approximately 15% of women between the ages of 30 and 50. Diagnosis is difficult because women present different forms of excessive menses and no simple objective ways of measuring menstrual blood loss exist. A pictorial blood assessment chart was therefore validated for a better management of heavy menstrual bleeding. In half of the cases, no gynaecologic cause is found. Therefore, blood tests should be performed aiming at identifying coagulation disorders. We present here the results of our small series. Identification of coagulation disorders may allow specific treatments. These improve the quality of life and prevent unnecessary radical measures such as notably, hysterectomies.

[Haemostasis. A search for an ideal antithrombotics agent]

Heparins and vitamin K antagonist are the main antithrombotic agents used since several years. These two classes of drugs are very effective but not devoid of side effects and require either injections or regular laboratory controls. Therefore new agents have been developed. Two of these agents (fondaparinux and ximelagatran) are already available. Both are of non animal origin, do not induce thrombocytopenia and do not require laboratory controls. In recent studies fondaparinux has shown a better efficacy than low molecular weight heparin in major orthopedic interventions. Ximelagatran, which can be given orally, is now admitted also for short term use. It was hoped that it could replace vitamin K antagonists but increase of liver enzymes occurring after a few weeks is a major problem. Other new drugs are in advanced stage and will be also described.

Deep venous thrombosis and thrombophilia: indications for testing and clinical implications

In the past 3 decades, numerous biological abnormalities linked with deep venous thrombosis have been described. Among the different possibilities, it is crucial to order tests that can modify the therapeutic attitude towards the patient and/or his family. A combined clinical and laboratory approach taking into account the history of the patient and his family, the prevalence of the defects, and also the accuracy of the tests should allow tailoring a laboratory testing program to each patient. It is essential to keep in mind that the more difficult task is not to perform the tests but to consider who will benefit from testing both for prevention and therapy of venous thromboembolism. This article provides answers to some of these issues. These answers should, however, be considered as tentative and provisional because new findings and study results will certainly modify them in the near future.

Aspirin inhibits endothelial cell activation induced by antiphospholipid antibodies

BACKGROUND

Antiphospholipid antibodies (APLA) have been shown to activate endothelial cells (EC) in vitro, as documented by an increased expression of tissue factor as well as leukocyte adhesion molecules such as intercellular adhesion molecule-1, vascular cell adhesion molecule (VCAM)-1 and E-selectin. Currently, treatment of patients with the antiphospholipid syndrome includes aspirin, particularly for women with recurrent fetal loss.

OBJECTIVE

The present study was undertaken to investigate whether aspirin interferes with EC activation induced by APLA in vitro.

METHODS

IgG from 14 patients with APLA, and suffering from thrombotic complications and/or pregnancy morbidity, and control IgG were tested for their ability to modify the expression of VCAM-1 in human umbilical vein endothelial cells. VCAM-1 antigen was measured by flow cytometry and its mRNA by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Incubation of EC with IgG from most of the patients led to a higher VCAM-1 expression compared with incubation with control IgG. The effect of aspirin was studied for the eight IgG samples that induced a more than 50% increase in VCAM-1. Aspirin (10 mm) treatment of the cells significantly reduced the VCAM-1 response to these APLA.

CONCLUSIONS

Our results indicate that besides its antiplatelet properties, aspirin exerts a protective effect towards APLA at the EC level by decreasing leukocyte adhesion molecule expression at the cell surface.

Severe thrombocytopenic purpura due to rubella infection in a patient with systemic lupus erythematosus

We report the case of a woman suffering from systemic lupus erythematosus who developed a severe thrombocytopenic purpura (platelet count < 1 x 10(9)/l) secondary to rubella infection. The search for antiplatelet antibodies revealed transient circulating anti-GPIIb-IIIa and anti-GPIb-IX platelet antibodies. After a few weeks, bound anti-GPIIb-IIIa antiplatelet antibodies were still detectable and they persisted several months after recovery, probably in relation to a mild autoimmune thrombocytopenia related to systemic lupus erythematosus. To our knowledge, this is the first case report of severe thrombocytopenic purpura due to rubella in an adult with systemic lupus erythematosus.

Platelet chemokines and their receptors: what is their relevance to platelet storage and transfusion practice?

The role of platelets as inflammatory cells is demonstrated by the fact that they can release many growth factors and inflammatory mediators, including chemokines, when they are activated. The best known platelet chemokine family members are platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG), which are synthesized in megakaryocytes, stored as preformed proteins in alpha-granules and released from activated platelets. However, platelets also contain many other chemokines such as interleukin-8 (IL-8), growth-regulating oncogene-alpha(GRO-alpha), epithelial neutrophil-activating protein 78 (ENA-78), regulated on activation normal T expressed and secreted (RANTES), macrophage inflammatory protein-1alpha (MIP-1alpha), and monocyte chemotactic protein-3 (MCP-3). They also express chemokine receptors such as CCR4, CXCR4, CCR1 and CCR3. Platelet activation is a feature of many inflammatory diseases such as heparin-induced thrombocytopenia, acquired immunodeficiency syndrome, and congestive heart failure. Substantial amounts of PF4, beta-TG and RANTES are released from platelets on activation, which may occur during storage. Although very few data are available on the in vivo effects of transfused chemokines, it has been suggested that the high incidence of adverse reactions often observed after platelet transfusions may be attributed to the chemokines present in the plasma of stored platelet concentrates.

TAFI antigen and D-dimer levels during normal pregnancy and at delivery

We have investigated whether the levels of thrombin-activatable fibrinolysis inhibitor (TAFI) were correlated with D-dimer levels during pregnancy and at delivery. From the 10th week of pregnancy to delivery, 519 samples from 144 women (mean age 29.3 +/- 5, range 19-43) were obtained. We confirm the gradual increase of D-dimer levels, and provide reference intervals for D-dimer measurements throughout normal pregnancy. TAFI levels increased moderately during pregnancy but no inverse correlation with D-dimer levels was observed.

Severe neonatal alloimmune thrombocytopenia due to anti-HPA-3a

BACKGROUND AND OBJECTIVES

Neonatal alloimmune thrombocytopenia is usually attributable to HPA-la antibodies. We report a case of parental platelet antigen incompatibility associated with a severe neonatal thrombocytopenia secondary to alloimmunization to HPA-3a.

MATERIALS AND METHODS

Platelet antibodies were detected by the monoclonal antibody-specific immobilization of platelet antigens, genotyping of the platelets by PCR, and HLA typing by serologic procedures and PCR.

RESULTS

Genotyping of maternal and paternal platelets confirmed the incompatibility in the HPA-3a system. It is noteworthy that the mother is of the HLA type DRB3*0101, is ABO-incompatible with her husband, and also has HLA class I antibodies.

CONCLUSION

Severe neonatal thrombocytopenia associated with HPA-3a alloimmunization is infrequent and all the factors mentioned above could have played a role in the severity of the disease.

Platelet count at term pregnancy: a reappraisal of the threshold

OBJECTIVE

To assess the safety of a new platelet count threshold for the definition of maternal thrombocytopenia late in pregnancy.

METHODS

A platelet count was performed in 6770 pregnant women late in pregnancy and in 6103 of their newborns as well as in a control group of 287 age-matched nonpregnant healthy women.

RESULTS

The prevalence of maternal thrombocytopenia (platelet count less than 150 x 10(9)/L) was 11.6%. The mean platelet counts (248 compared with 213 x 10(9)/L) and 2.5th percentile (164 compared with 116 x 10(9)/L) were significantly higher in healthy nonpregnant women than in pregnant women. Among thrombocytopenic pregnant women, 621 (79%) had platelet counts between 116 and 149 x 10(9)/L; none (0%; 95% confidence interval 0, 0.6) had complications related to thrombocytopenia, and none of their newborns had severe thrombocytopenia (platelet count less than 20 x 10(9)/L).

CONCLUSION

In healthy pregnant women, a platelet count over 115 x 10(9)/L late in pregnancy does not require further investigation during pregnancy and may be considered a safe threshold.

Maternal antiplatelet antibodies in predicting risk of neonatal thrombocytopenia

OBJECTIVE

To determine the incidence of maternal antiplatelet antibodies in cases of thrombocytopenia during pregnancy, using the monoclonal antibody-specific immobilization of platelet antigens assay; and to assess the usefulness of this assay for predicting risk of neonatal thrombocytopenia.

METHODS

A total of 6770 pregnant women were included in the study, and the monoclonal antibody-specific immobilization of platelet antigens assay was done when platelet counts were less than 150 x 10(9)/L. Platelet counts were determined in 6103 newborns.

RESULTS

The incidence of maternal thrombocytopenia was 11.6% (95% confidence interval [CI] 10.8, 12.4). Among newborns, 1.3% (95% CI 0.5, 2.7) born to thrombocytopenic mothers were thrombocytopenic, compared with 0.4% (95% CI 0.2, 0.6) born to nonthrombocytopenic women. Antiplatelet antibodies were detected in 37 (8.6%) of 430 thrombocytopenic women; autoantibodies were detected in 28 cases (circulating or bound to platelets), alloantibodies in eight cases, and an association of alloantibodies and autoantibodies in one case. The positive and negative likelihood ratios for predicting neonatal thrombocytopenia were 4.6 and 0.7, respectively.

CONCLUSION

The monoclonal antibody-specific immobilization of platelet antigens assay did not predict the risk of neonatal thrombocytopenia in an unselected population of thrombocytopenic pregnant women.

Evaluation of a new antigen capture ELISA for detection and characterization of platelet alloantibodies

The monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay is considered as a possible reference method for the detection of maternal alloantibodies when a foetomaternal alloimmunization is suspected. However, this method is tedious. In this study, we have compared the MAIPA results of 54 samples of mothers with (n=34) or without (n=20) alloantibodies with those obtained with a new antigen capture ELISA. Using the cutoff of 2.0 given by the manufacturer, the new kit had a sensitivity of 88.2% (95% CI 72.6-96.7) and a specificity of 100% (95% CI 98.0-100). From a receiver-operating characteristic curve analysis, the more appropriate cutoff for a screening assay would be 1.6, which gives a sensitivity of 100% (95% CI 89.7-100) with a specificity of 94.0% (95% CI 89.4-96.9). In conclusion, this new simple assay appears promising and could be used, with the modified cutoff, as a screening assay for the detection of platelet alloantibodies.