Effects of anti-Xa activity monitoring on the outcome of high-risk pregnancies treated with a prophylactic dose of low-molecular-weight heparin.

OBJECTIVE: To evaluate if anti-Xa level monitoring and dose adjustment in women using a prophylactic dose of enoxaparin can decrease placenta-mediated pregnancy complications. METHODS: This retrospective observational cohort study included pregnant women receiving enoxaparin prophylaxis, who were followed at the Thrombosis and Hemostasis Outpatient clinic between 2010 and 2017. The dose was adjusted according to enoxaparin anti-Xa levels in the study group or the weight of individuals in the control group. RESULTS: Of 585 women surveyed, 110 met the inclusion criteria; 63 of them were included in the study group and 47 in the control group. Mean starting dose was 46 versus 43 mg (p = .25), mean final dose was 52 mg versus 45 mg (p = .03) and dose adjustment was required in 37% versus 11% (p = .002) in the study and control groups, respectively. Twenty-eight percent of anti-Xa measurements in the second trimester were beneath the prophylactic threshold, compared to 11% and 16% in the first and third trimesters, respectively (p = .02). Labors ended with live birth in 91% versus 94% of cases (p = .5), 85% versus 68% of pregnancies were term (p = .05), 11% versus 23% of newborns were low birth weight (p = .1) and placenta-mediated pregnancy complications were documented in 9% versus 19%, (p = .17) in the study group relative to controls, respectively. CONCLUSIONS: The most prominent decrease in anti-Xa levels was observed in the second trimester. Monitored women had significantly more term deliveries and demonstrated a trend toward higher birth weight and fewer placenta-mediated pregnancy complications. Larger studies are needed to confirm improved pregnancy outcome in monitored women.

A 14-Year Experience in the Management of Patients with Acquired Immune Thrombotic Thrombocytopenic Purpura in Northern Israel.

Acquired idiopathic thrombotic thrombocytopenic purpura (I-TTP) is a life-threatening microangiopathic disorder usually treated with therapeutic plasma exchange (TPE). The current study assessed the role of rituximab in the treatment of complicated I-TTP. The sequence of TTP events was compared in a group of I-TTP patients treated with TPE and a cohort of refractory or relapsed patients who also received rituximab. This retrospective evaluation included 45 I-TTP patients, treated between January 2000 and October 2013, who underwent at least 3 TPE procedures and were followed up until December 2013 or death. Thirty-one patients with an uncomplicated course received TPE only. Fourteen patients had a complicated course due to either a primary refractory/exacerbated disease (n = 5) or relapse (n = 9) and received rituximab together with TPE. The median number of TPE procedures performed in the first TTP episode in the uncomplicated cohort and groups with primary refractory or relapsed TTP was 11, 27 and 45, respectively. The relapse rates per follow-up year in the uncomplicated I-TTP, primary refractory and relapsed I-TTP groups were 0.18, 0.2 and 0.6 episodes, respectively. After rituximab therapy this rate dropped to 0.2 per year in the relapsed subgroup. In conclusion, about a quarter of patients with I-TTP had a complicated course and experienced a major benefit from rituximab in terms of effectiveness and safety.

Heparin-induced thrombocytopenia in myeloproliferative disorders: a rare or under-diagnosed complication?

Patients with myeloproliferative disorders (MPD) are prone to develop thrombotic complications and thus frequently receive heparin. Surprisingly heparin-induced thrombocytopenia (HIT) has been rarely reported in MPD and is potentially under-diagnosed due to the relatively high platelet count. We report three patients with MPD who developed HIT; all presented with a relative fall of platelet counts (although without an absolute thrombocytopenia), thrombosis or skin necrosis and a positive test for HIT antibodies (particle gel immunoassay). Risk factors for developing HIT in our patients were exposure to unfractionated heparin, a recent surgical procedure and female gender. We review the literature on HIT in MPD and discuss the diagnosis of HIT in the absence of an absolute thrombocytopenia.

Evaluation of ProC Global assay in women with a history of venous thromboembolism on hormonal therapy.

The risk of thrombosis in women increases significantly during treatment with hormonal therapy (HT). The aim of this study was to evaluate ProC Global assay in women with a history of venous thromboembolism (VTE) while using HT. Protein C activation time normalized ratio (PCAT-NR) levels were significantly lower in 32 women with a history of VTE while using HT (0.72 +/- 0.1) compared with 56 healthy controls without HT, matched by age at blood sampling (0.99 +/- 0.2) and 40 healthy controls with HT, matched by age and HT at VTE event (0.94 +/- 0.2) (P < 0.001 for both). PCAT-NR lower than the cut-off level of 0.8 was found in 23/32 (72%) patients compared with 5/56 (9%) age-matched controls (OR = 26, 95%CI: 7-106, P < 0.001) and 9/40 (22.5%) of HT-matched controls (OR = 9, 95%CI: 2.7-30, P < 0.001). Any thrombophilic risk factor was found in 20/32 (62.5%) of patients compared with 12/56 (21.4%) of agematched controls (OR = 6, 95%CI: 2.1-10, P < 0.001) and 12/40 (30%) of HT-matched controls (OR = 4, 95%CI: 1.3-11.8, P = 0.006). Out of the variables that are risk factors of VTE as age, HT or thrombophilic risk factor, ProC Global assay was found in the multivariate analysis - logistic regression, as the parameter that was the most associated with patient group [Exp(B) = 15.8, 95% CI: 4.2-59.0, P < 0.001]. In conclusion, abnormal PCAT-NR is associated with VTE in women using HT. ProC Global assay may potentially serve as a diagnostic tool for evaluating the risk of VTE in women prior to administration of HT.

Absence of association of inherited thrombophilia with unexplained third-trimester intrauterine fetal death.

OBJECTIVE: The purpose of this study was to investigate the alleged association between thrombophilia and unexplained third-trimester stillbirth. STUDY DESIGN: Case subjects were 37 women with a history of a third-trimester unexplained stillbirth. Control subjects were 46 volunteers, group-matched for ethnic origin, with no history of stillbirth, recurrent fetal loss, or thromboembolism. The pathology report of 34/37 placentas of case subjects was reviewed. RESULTS: The prevalence of at least 1 inherited thrombophilia among case subjects was 37.8% compared with 41.3% among control subjects. (OR = 0.87; 95%CI, 0.32-2.29). There was no significant difference between the groups with respect to the prevalence of any single inherited thrombophilia. There was, however, a significantly higher prevalence of antiphospholipid antibodies among case subjects compared with control subjects: 47.2% vs 8.7%, respectively (OR = 9.4; 95%CI, 2.5-42.3). No significant difference was noted in the prevalence of thrombopilia among subjects with or without placental infarcts. CONCLUSION: We did not find an association between unexplained third-trimester intrauterine fetal death and inherited thrombophilia; however, we did find such an association with antiphospholipid antibodies.