Inheritance and bleeding in factor XI deficiency

Laboratory and Molecular Diagnosis of Factor XI Deficiency

The prevalence of factor XI (FXI) deficiency is 1 per 10 to 20,000 in the general population, much higher than that reported in most texts. The prevalence is higher in Ashkenazi Jews where it is about 1:20. Clinically, FXI deficiency presents as a mild bleeding disorder mostly associated with posttraumatic or postsurgical hemorrhages or unexplained minor bleeding. It is often discovered due to incidental finding of a prolonged activated partial thromboplastin time (aPTT) on routine laboratory screening. FXI deficiency is an autosomal recessive bleeding disorder with many causative F11 gene defects. Diagnosis is based on FXI activity, antigen levels, and molecular diagnostics. As FXI levels do not correlate with bleeding symptoms, identification of pathogenic genetic variants may be a more accurate predictor of bleeding risk and therefore aid in the clinical management of the patient. Two variants in the F11 gene account for most cases found in the Jewish and Arab populations. Patients with FXI deficiency can develop inhibitors to FXI although spontaneously acquired inhibitors are extremely rare. We will discuss laboratory and molecular assays used to diagnose FXI deficiency as well as interferences that can complicate diagnosis including new anticoagulants and acquired FXI inhibitors.

Factor XIa inhibition as a therapeutic strategy for atherothrombosis

When selecting an anticoagulant, clinicians consider individual patient characteristic, the treatment indication, drug pharmacology, and safety and efficacy as demonstrated in randomized trials. An ideal anticoagulant prevents thrombosis with little or no increase in bleeding. Direct oral anticoagulants represent a major advance over traditional anticoagulants (e.g., unfractionated heparin, warfarin) but still cause bleeding, particularly from the gastrointestinal tract which can limit their use. Epidemiological studies indicate that patients with congenital factor XI (FXI) deficiency have a lower risk of venous thromboembolism (VTE) and ischemic stroke (IS) than non-deficient individuals, and do not have an increased risk of spontaneous bleeding, even with severe deficiency. These observations provide the rationale for targeting FXI as a new class of anticoagulant. Multiple FXI inhibitors have been introduced and several are being evaluated in Phase III trials. In this review, we explain why drugs that target FXI may be associated with a lower risk of bleeding than currently available anticoagulants and summarize the completed and ongoing trials.

Testing strategies used in the diagnosis of rare inherited bleeding disorders

INTRODUCTION

Rare Bleeding Disorders have a low population prevalence and may not be recognized by most clinicians. In addition, knowledge gaps of the indicated laboratory tests and their availability add to the potential for delayed diagnosis or misdiagnosis. The lack of widely available commercial, regulatory body approved esoteric tests limit them to reference laboratories, thus limiting easy access for patients.

AREAS COVERED

A literature search of Pubmed, Medline, Embase and review of international society guidelines was performed. Additional references from published articles were reviewed. A patient-centered approach to recognition and evaluation of RBD is discussed.

EXPERT OPINION

Recognition of RBD relies on obtaining a detailed patient personal and family hemostatic history. Inquiry into a history of involvement of other organ systems is important and if present should lead to suspicion of an inherited platelet disorder or a variant of Ehlers Danlos Syndrome. Multiple factors contribute to the complexity of development of efficient algorithms for diagnostic testing. Limitations in diagnostic sensitivity and specificity of screening tests, diagnostic tests, and esoteric tests further compound the complexity of establishing a diagnosis. Educational efforts focusing on clinician awareness of RBDs and available testing options are vital for optimal management of such patients.

Perioperative Management of a Patient with Hemophilia C and Allergy to Fresh Frozen Plasma

Hemophilia C is a rare bleeding disorder characterized by a deficiency in clotting factor XI (fXI) and has no standard of care for preoperative optimization before cardiac surgery. Normalization of fXI levels in patients with hemophilia C can be achieved with fresh frozen plasma (FFP), which sometimes results in allergic reactions. We present a case of a patient with hemophilia C requiring coronary artery bypass grafting surgery who developed an allergic reaction to FFP. Our report underscores the balance between thrombosis and bleeding risks when devising a perioperative plan for patients with hemophilia C.

Tissue factor pathway inhibitor is a potential modifier of bleeding risk in factor XI deficiency

BACKGROUND

Factor (F) XI deficiency is associated with increased bleeding risk in some individuals. Neither FXI levels nor clinical clotting assays predict the bleeding risk. Compared with controls, FXI-deficient bleeders have reduced clot formation, decreased fibrin network density, and increased susceptibility to fibrinolysis. Tissue factor pathway inhibitor (TFPI) was recently implicated as a modifying factor in individuals with bleeding of unknown cause.

OBJECTIVES

To determine the potential of TFPI in modifying the bleeding risk in FXI-deficient individuals.

METHODS

The effects of TFPI on thrombin generation and clot formation, structure, and fibrinolysis in FXI-deficient plasma were measured in vitro in the absence or presence of inhibitory anti-TFPI antibody or exogenous recombinant TFPIα. Total plasma TFPI concentration was measured in 2 independent cohorts of controls and FXI-deficient individuals classified as bleeders or nonbleeders (cohort 1: 10 controls and 16 FXI-deficient individuals; cohort 2: 48 controls and 57 FXI-deficient individuals) and correlated with ex vivo plasma clot formation and fibrinolysis parameters associated with bleeding risk.

RESULTS

In an in vitro FXI deficiency model, inhibition of TFPI enhanced thrombin generation and clot formation, increased the network density, and decreased fibrinolysis, whereas an increase in TFPI had the opposite effects. Compared with controls, plasma from FXI-deficient bleeders had higher TFPI concentration. Total plasma TFPI concentrations correlated with parameters from ex vivo clotting and fibrinolysis assays that differentiate FXI-deficient bleeders and nonbleeders.

CONCLUSION

Coagulation and fibrinolysis parameters that differentiate FXI-deficient nonbleeders and bleeders were altered by plasma TFPIα. Total plasma TFPI was increased in FXI-deficient bleeders. TFPI may modify the bleeding risk in FXI-deficient individuals.

Epidural analgesia in a patient with factor XI deficit

FXI deficiency is a rare bleeding disorder characterised by a decreased level or activity of factor. Pregnant women are at increased risk of uterine bleeding during childbirth. Neuroaxial analgesia may increase the risk of epidural hematoma in these patients. However, there is no consensus on the anaesthetic management. We present the clinical case of a 36-year-old woman with a personal history of factor XI deficiency, pregnant with 38 weeks gestation who is scheduled to perform birth induction. Pre-induction factor levels were measured. They were less than 40%, so it was decided to transfuse 20 ml/kg of fresh frozen plasma. After the transfusion it had levels greater than 40%, so epidural analgesia was performed without incident. The patient had no complications secondary to epidural analgesia or transfusion of a high volume of plasma.

Molecular heterogeneity of factor XI deficiency in Tunisia

Factor XI (FXI) deficiency is a rare inherited bleeding disorder that is highly prevalent in Ashkenazi Jewish ancestry but sporadically observed in most ethnic groups. It is heterogeneous both in clinical presentation and in genetic causality. Although a large spectrum of mutations associated with this disorder has been reported in several populations, genetic data of FXI deficiency in Tunisia are poorly described. The purpose of this study was to determine the molecular basis of FXI deficiency among Tunisian patients. Fourteen index cases from nine unrelated families with FXI deficiency, referred to Hemophilia Treatment Center of Aziza Othmana Hospital, were included in this study. The patients' F11 genes were amplified by PCR and subjected to direct DNA sequencing analysis. Sequencing analysis of F11 genes identified three distinct mutations; the Jewish type II nonsense mutation E117X, one previously reported missense mutation E602Q and one novel missense mutation V271M, which led to the disruption of the third apple domain structure of FXI. Furthermore, seven polymorphisms previously described, were also detected: C321F, c. 294A>G, -138 A>C, p.D125D, p.T249T, p.G379G, p.D551D. This report represents the first genetic study analyzing the molecular characteristics of factor XI deficiency within Tunisian population. Identification of the Jewish type II mutation in two families, as well as one missense previously reported mutation and one novel mutation confirmed the genetic heterogeneity of this disorder. Screening a large number of Tunisian factor XI deficient would reveal the spectrum mutations causing factor XI deficiency in Tunisia.

Maternal and foetal outcomes following natural vaginal versus caesarean section (c-section) delivery in women with bleeding disorders and carriers

BACKGROUND

Bleeding disorders are uncommon but may pose significant bleeding complications during pregnancy, labour and following delivery for both the woman and the foetus. While many bleeding disorders in women tend to improve in pregnancy, thus decreasing the haemorrhagic risk to the mother at the time of delivery, some do not correct or return quite quickly to their pre-pregnancy levels in the postpartum period. Therefore, specific measures to prevent maternal bleeding and foetal complications during childbirth, are required. The safest method of delivery to reduce morbidity and mortality in these women is controversial. This is an update of a previously published review.

OBJECTIVES

To assess the optimal mode of delivery in women with, or carriers of, bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the Cochrane Pregnancy and Childbirth Group's Trials Register as well as trials registries and the reference lists of relevant articles and reviews. Date of last search of the Group's Trials Registers: 21 June 2021.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled clinical trials investigating the optimal mode of delivery in women with, or carriers of, any type of bleeding disorder during pregnancy were eligible for the review.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No trials matching the selection criteria were eligible for inclusion.

AUTHORS' CONCLUSIONS

The review did not identify any randomised controlled trials investigating the safest mode of delivery and associated maternal and foetal complications during delivery in women with, or carriers of, a bleeding disorder. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials, case studies) to decide upon the optimal mode of delivery to ensure the safety of both mother and foetus. Given the ethical considerations, the rarity of the disorders and the low incidence of both maternal and foetal complications, future randomised controlled trials to find the optimal mode of delivery in this population are unlikely to be carried out. Other high quality controlled studies (such as risk allocation designs, sequential design, and parallel cohort design) are needed to investigate the risks and benefits of natural vaginal and caesarean section in this population or extrapolation from other clinical conditions that incur a haemorrhagic risk to the baby, such as platelet alloimmunisation.

The Association between Factor XI Deficiency and the Risk of Bleeding, Cardiovascular, and Venous Thromboembolic Events

The objective of this study was to assess the relationship between factor XI (FXI) deficiency and the risks of bleeding and cardiovascular (CV) events. We conducted a retrospective cohort study using data from Maccabi Healthcare Services (MHS). We identified adults with FXI deficiency (severe: <15%, partial: 15 to <50%, any deficiency: <50%) that had been tested for FXI between 2007 and 2018 and matched to patients from the general MHS population. We estimated 10-year risks of outcomes using the Kaplan–Meier approach. Using Cox proportional hazards regression, we compared outcomes among patients with versus without FXI deficiency. Less than 10% of patients tested for FXI activity had activity levels <50% (mean age: 39 years; 72.2% females). Compared with the general population, patients with any FXI deficiency were at higher risk of severe bleeding (adjusted hazard ratio [aHR]: 2.56, 95% confidence interval [CI]: 1.13–5.81; 10-year risk: 1.90%, 95% CI: 0.50–3.20% vs. 0.90%, 95% CI: 0.50–1.30%) and clinically relevant nonsevere bleeding (CRNSB) (aHR: 1.45, 95% CI: 1.08–1.97; 10-year risk: 11.60%, 95% CI: 8.30–14.80% vs. 9.20%, 95% CI: 8.00–10.40%). Severe FXI deficiency was associated with a greater risk of CRNSB. While few CV events ( N  = 2) and venous thromboembolisms (VTE) ( N  = 1) were observed in the FXI overall deficient group, there was a nonsignificant negative association between any FXI deficiency and CV events (aHR: 0.55; 95% CI: 0.13–2.36) and VTEs (aHR: 0.45; 95% CI: 0.06–3.47). Overall FXI deficiency was associated with an increased risk of severe bleeding and CRNSB. Further research is warranted to explore the lower risk of CV and VTE among patients with FXI deficiency compared with the general population.

[Congenital factor Ⅺ deficiency: a retrospective analysis of 80 cases]

目的

分析遗传性凝血因子Ⅺ（FⅪ）缺乏症的临床表现、实验室检查、治疗及转归。

方法

对2006年9月至2020年10月就诊于中国医学科学院血液病医院的80例遗传性FⅪ缺乏症患者进行回顾性分析。结果 80例患者中，男33例（41.3％），女47例（58.8％），中位年龄32（2～66）岁。28例（35.0％）存在出血事件，其中自发性出血11例（13.8％），皮肤磕碰后瘀斑或出血9例（11.3％），手术后出血9例（11.3％），女性患者月经过多11例（23.4％），阴道分娩后出血1例（2.1％）。实验室检查表现为活化部分凝血活酶时间（APTT）延长、凝血酶原时间（PT）正常、FⅪ活性（FⅪ∶C）减低。9例（11.3％）患者接受F11基因检测，共检测到11种突变。27例（33.8％）患者接受新鲜冰冻血浆（FFP）治疗，15例（18.8％）手术前预防性输注患者均未发生术中、术后出血。

结论

多数遗传性FⅪ缺乏症患者无出血症状或症状轻微，FⅪ∶C与出血严重程度之间缺乏相关性，FⅪ∶C与F11基因纯合或杂合突变类型具有较好的一致性。预防性输注FFP可有效降低手术出血风险。

Pharmacological management of rare coagulation factor deficiencies besides hemophilia

INTRODUCTION

Rare coagulation factor deficiencies are less-known disorders with variable effects on the patient's life. Management of such patients is a challenge due to the paucity of evidence-based data, more so when patients with these rare disorders encounter a more rare, related condition, like inhibitor development or thrombosis.

AREA COVERED

A comprehensive literature search related to RCFDs and management was performed in PubMed in order to discuss therapeutic options and challenges, prophylaxis, management of minor and major surgeries, obstetric and gynecological complications, inhibitor development, and thrombosis.

EXPERT OPINION

Although significant changes have occurred in the management of RCFDs in recent years, more evidence-based studies besides expert opinion are needed for optimal management.

Tissue Factor-Independent Coagulation Correlates with Clinical Phenotype in Factor XI Deficiency and Replacement Therapy

BACKGROUND

 In factor XI (FXI) deficiency, bleeding cannot be predicted by routine analyses. Since FXI is involved in tissue factor (TF)-independent propagation loop of coagulation, we hypothesized that investigating the spatiotemporal separated phases of coagulation (TF-dependent and -independent) could improve diagnostics.

OBJECTIVES

 This article investigates the correlation of parameters describing TF-dependent and -independent coagulation with the clinical phenotype of FXI deficiency and their ability to assess hemostasis after FXI replacement.

METHODS

 We analyzed: (1) plasma from healthy controls (n = 53); (2) normal plasma (n = 4) spiked with increasing concentrations of a specific FXI inhibitor (C7P); (3) plasma from FXI-deficient patients (n = 24) with different clinical phenotypes (13 bleeders, 8 non-bleeders, 3 prothrombotics); (4) FXI-deficient plasma spiked with FXI concentrate (n = 6); and (5) plasma from FXI-deficient patients after FXI replacement (n = 7). Thrombin generation was measured with the reference method calibrated automated thrombogram and with Thrombodynamics (TD), a novel global assay differentiating TF-dependent and -independent coagulation.

RESULTS

 C7P dose-dependently decreased FXI activity, prolonged activated partial thromboplastin time, and hampered TF-independent coagulation. In FXI-deficient bleeders, TD parameters describing TF-independent propagation of coagulation and fibrin clot formation were reduced compared with controls and FXI-deficient nonbleeders and increased in FXI-deficient patients with prothrombotic phenotype. Receiver operating characteristic analysis indicated that TF-independent parameters were useful for discriminating FXI-deficient bleeders from non-bleeders. In FXI-deficient plasma spiked with FXI concentrate and in patients receiving FXI replacement, TD parameters were shifted toward hypercoagulation already at plasma FXI levels around 20%.

CONCLUSION

 TF-independent coagulation parameters assessed by TD have the potential to identify the clinical phenotype in FXI-deficient patients and to monitor FXI replacement therapy.

A case of arthroscopic ankle arthrodesis for hemophilic arthropathy of the bilateral ankles

•

We successfully treated hemophilic arthropathy in both ankles with arthroscopic arthrodesis.

•

In surgery for patients with hemophilia, perioperative supplementation of the deficient coagulation factor was necessary.

•

There were many advantages in arthroscopic ankle arthrodesis, compared to open ankle arthrodesis.

Introduction

Hemophilic arthropathy can affect multiple joints including ankle. However, only one report has been published regarding both arthroscopic ankle arthrodesis with hemophilic arthropathy.

Presentation of case

The patient was a 23-year-old man with hemophilia A and a 3-year history of recurrent hemarthrosis in both ankles. We undertook surgery to treat arthropathy. His left ankle was treated first and the right ankle 6 months later. In both ankles, the cartilage was worn and eburnated. The remaining cartilage was removed and more dimples were created to fuse the tibia and talus. The ankle was fixed using 3 cannulated screws. Postoperatively, the patient wore an immobilization cast with no weight-bearing for 2 weeks. Thereafter, weight-bearing was allowed and the cast was removed 4 weeks after surgery.

Discussion

At the 1-year follow-up, bony union was satisfactory, functional outcome was acceptable, and pain relief was good. The Japanese Society for Surgery of the Foot ankle-hindfoot scale score increased from 24 preoperatively to 87 postoperatively.

Conclusion

We report successful treatment with arthroscopic arthrodesis in a case of hemophilic arthropathy in both ankles.

Heterozygote carriers of mutations in the F11 gene, encoding Factor XI, have normal coagulation by thromboelastography during pregnancy

BACKGROUND

Evidence to guide clinical decision-making in pregnant women who are usually asymptomatic, but identified as heterozygote carriers of F11 mutations, is lacking. We hypothesized that women identified on prenatal screening as heterozygous for a mutation in the F11 allele would have minimal evidence of an in vitro coagulation abnormality.

METHODS

We prospectively enrolled women identified by prenatal screening as F11 mutation carriers and pregnant women who were presumed to be normal as controls. We collected blood during antepartum visits or at presentation for delivery and assessed Factor XI (FXI) coagulant activity level, as well as whole-blood coagulation, by thromboelastography.

RESULTS

F11 mutation carriers had lower serum FXI activity levels than controls (51.2 ± 8.5% vs 94.1 ± 19.4%; P <0.0001). Thromboelastography values of all control subjects and F11 mutation carriers were within the normal range. The R-time was slightly longer in F11 mutation carriers (5.3 ± 1.0 s vs 4.2 ± 0.8 s, P <0.002), but no other statistically significant differences in thromboelastogram parameters were identified between groups.

CONCLUSIONS

Despite lower FXI activity in the F11 mutation group, we found minimal differences in whole-blood measures of coagulation using thromboelastography. These findings support our hypothesis that a single copy of an F11 mutation does not produce significant evidence of an in vitro coagulation abnormality. Thromboelastography might be useful in determining the risk of neuraxial anesthesia in pregnant women, but additional work is required to establish the validity of this test.

Severe Ankle Arthritis After Multiple Hemarthrosis Secondary to Factor XI Deficiency: A Case Report

Hemophilic arthropathy of the ankle is an extremely unique condition that affects a small subset of the population in the United States. We present the case of a 66-year-old male with factor XI deficiency, which, over years of repetitive microtrauma as a professional soccer player, led to multiple hemarthrosis and severe arthropathy of his right ankle. The patient successfully underwent total ankle replacement arthroplasty and was able to return to recreational sports and competitive road cycling.

Desmopressin acetate (DDAVP) for preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders

BACKGROUND

Congenital bleeding disorders can cause obstetric haemorrhage during pregnancy, labour and following delivery. Desmopressin acetate (DDAVP) is found to be an effective drug which can reduce the risk of haemorrhage and can also stop bleeding in certain congenital bleeding disorders. Its use in pregnancy has been controversial. Hence beneficial and adverse effects of DDAVP in these groups of pregnant women should be evaluated.This is an update of a Cochrane Review first published in 2013 and updated in 2015.

OBJECTIVES

To evaluate the efficacy and safety of DDAVP in preventing and treating acute bleeding in pregnant women with bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant and abstract books of conferences proceedings. We also searched several clinical trial registries and grey literature (27 August 2017).Date of most recent search of the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register: 01 October 2018.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials investigating the efficacy of DDAVP versus tranexamic acid or factor VIII or rFactor VII or fresh frozen plasma in preventing and treating congenital bleeding disorders during pregnancy were eligible.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No trials matching the selection criteria were eligible for inclusion.

AUTHORS' CONCLUSIONS

No randomised controlled trials were identified investigating the relative effectiveness of DDAVP for bleeding during pregnancy in women with congenital bleeding disorders. In the absence of high-quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials) to decide whether or not to treat women with congenital bleeding disorders with DDAVP.Given the ethical considerations, future randomised controlled trials are unlikely. However, other high-quality controlled studies (such as risk allocation designs, sequential design, parallel cohort design) to investigate the risks and benefits of using DDAVP in this population are needed.Given that there are unlikely to be any trials published in this area, this review will no longer be regularly updated.

Emicizumab, the bispecific antibody to factors IX/IXa and X/Xa, potentiates coagulation function in factor XI-deficient plasma in vitro

Essentials Emicizumab mimics factor (F)VIIIa cofactor function, augments the intrinsic tenase activity. We assessed the emicizumab-driven hemostatic function in FXI-deficient plasmas. Emicizumab improved the coagulation potentials in severe FXI-deficient plasma. Emicizumab may provide a possibility for clinical application in patients with FXI deficiency. SUMMARY: Background Patients with factor (F)XI deficiency commonly present with markedly prolonged activated partial thromboplastin times (APTT), although bleeding phenotypes are heterogeneous. Emicizumab, a bispecific monoclonal antibody to FIX/FIXa and FX/FXa, mimics FVIIIa cofactor function on phospholipid (PL) surfaces. Antibody reactions were designed, therefore, to augment mechanisms during the propagation phase of blood coagulation. Aim To assess emicizumab-driven hemostatic function in FXI-deficient plasmas. Methods and Results Standard ellagic acid (Elg)/PL-based APTTs of different FXI-deficient plasmas (n = 13; FXI activity, < 1 IU dl-1 ) were markedly shortened dose dependently by the presence of emicizumab. To further analyze the effects of emicizumab, clot waveform analysis (CWA) in FXI-deficient plasmas with emicizumab, triggered by tissue factor (TF)/Elg demonstrated improvements in both clot times, reflecting the initiation phase, and coagulation velocity, which represents the propagation phase. Emicizumab also enhanced the TF/Elg-triggered thrombin generation in FXI-deficient plasmas dose-dependently although the degree of enhancement varied in individual cases. Thrombin generation with either FVII-deficient plasma or FIX-deficient plasma treated with anti-FXI antibody showed little or no increase by the co-presence of emicizumab, suggesting that the accelerated thrombin generation in FXI-deficient plasmas by emicizumab should depend on the FIXa-involved coagulation propagation initially triggered by FVIIa/TF. The ex vivo addition of emicizumab to whole blood from three patients with severe FXI deficiency demonstrated modest, dose-dependent improvements in Ca2+ -triggered thromboelastograms (NATEM mode). Conclusion Emicizumab appeared to improve coagulation function in severe FXI-deficient plasma, and might provide possibilities for clinical application in patients with FXI deficiency.

Rare congenital bleeding disorders

The rare congenital bleeding disorders are a heterogeneous group of diseases which include deficiencies of fibrinogen, prothrombin and factors V, V + VIII, VII, X, XI and XIII. They are usually transmitted as autosomal recessive disorders, and the prevalence of the severe forms ranges from one case in 500,000 for factor VII up to one in 2,000,000 for factor XIII in the general population. Patients with rare congenital bleeding disorders may have a broad spectrum of clinical symptoms, ranging from mucocutaneous bleeding to life-threatening haemorrhages, such as those occurring in the central nervous system. The treatment of these disorders is based principally on the replacement of the deficient factor using, when available, specific plasma-derived or recombinant products. The aim of this narrative review is to summarise current knowledge about these rare bleeding conditions.

Abnormal plasma clot formation and fibrinolysis reveal bleeding tendency in patients with partial factor XI deficiency

Individuals with factor XI (FXI) deficiency have a variable bleeding risk that cannot be predicted from plasma FXI antigen or activity. This limitation can result in under- or overtreatment of patients and risk of bleeding or thrombosis. Previously, plasma clot fibrinolysis assays showed sensitivity to bleeding tendency in a small cohort of patients with severe FXI deficiency. Here, we determined the ability of plasma clot formation, structure, and fibrinolysis assays to predict bleeding tendency in a larger, independent cohort of patients with severe and partial FXI deficiency. Patients were characterized as nonbleeders or bleeders based on bleeding after tonsillectomy and/or dental extraction before diagnosis of FXI deficiency. Blood was collected in the absence or presence of the contact pathway inhibitor corn trypsin inhibitor (CTI). Clotting was triggered in platelet-poor plasma with tissue factor, CaCl2, and phospholipids in the absence and presence of thrombomodulin or tissue plasminogen activator. Clot formation and fibrinolysis were assessed by turbidity and confocal microscopy. CTI-treated plasmas from bleeders showed significantly reduced clot formation and decreased resistance to fibrinolysis compared with plasmas from controls or nonbleeders. Differences were enhanced in the presence of CTI. A model that combines activated partial thromboplastin time with the rate of clot formation and area under the curve in fibrinolysis assays identifies most FXI-deficient bleeders. These results show assays with CTI-treated platelet-poor plasma reveal clotting and clot stability deficiencies that are highly associated with bleeding tendency. Turbidity-based fibrinolysis assays may have clinical utility for predicting bleeding risk in patients with severe or partial FXI deficiency.

Tissue Factor: An Essential Mediator of Hemostasis and Trigger of Thrombosis

Tissue factor (TF) is the high-affinity receptor and cofactor for factor (F)VII/VIIa. The TF-FVIIa complex is the primary initiator of blood coagulation and plays an essential role in hemostasis. TF is expressed on perivascular cells and epithelial cells at organ and body surfaces where it forms a hemostatic barrier. TF also provides additional hemostatic protection to vital organs, such as the brain, lung, and heart. Under pathological conditions, TF can trigger both arterial and venous thrombosis. For instance, atherosclerotic plaques contain high levels of TF on macrophage foam cells and microvesicles that drives thrombus formation after plaque rupture. In sepsis, inducible TF expression on monocytes leads to disseminated intravascular coagulation. In cancer patients, tumors release TF-positive microvesicles into the circulation that may contribute to venous thrombosis. TF also has nonhemostatic roles. For instance, TF-dependent activation of the coagulation cascade generates coagulation proteases, such as FVIIa, FXa, and thrombin, which induce signaling in a variety of cells by cleavage of protease-activated receptors. This review will focus on the roles of TF in protective hemostasis and pathological thrombosis.

2017 Scientific Sessions Sol Sherry Distinguished Lecture in Thrombosis: Factor XI as a Target for New Anticoagulants

The goal of anticoagulant therapy is to attenuate thrombosis without compromising hemostasis. Although the direct oral anticoagulants are associated with less intracranial hemorrhage than vitamin K antagonists, bleeding remains their major side effect. Factor XI has emerged as a promising target for anticoagulants that may be safer than those currently available. The focus on factor XI stems from epidemiological evidence of its role in thrombosis, the observation of attenuated thrombosis in factor XI-deficient mice, identification of novel activators, and the fact that factor XI deficiency is associated with only a mild bleeding diathesis. Proof-of-concept comes from the demonstration that compared with enoxaparin, factor XI knockdown reduces venous thromboembolism without increasing bleeding after elective knee arthroplasty. This article rationalizes the selection of factor XI as a target for new anticoagulants, reviews the agents under development, and outlines a potential path forward for their development.

Anticoagulation beyond direct thrombin and factor Xa inhibitors: indications for targeting the intrinsic pathway?

Antithrombotic drugs like vitamin K antagonists and heparin have been the gold standard for the treatment and prevention of thromboembolic disease for many years. Unfortunately, there are several disadvantages of these antithrombotic drugs: they are accompanied by serious bleeding problems, it is necessary to monitor the therapeutic window, and there are various interactions with food and other drugs. This has led to the development of new oral anticoagulants, specifically inhibiting either thrombin or factor Xa. In terms of effectiveness, these drugs are comparable to the currently available anticoagulants; however, they are still associated with issues such as bleeding, reversal of the drug and complicated laboratory monitoring. Vitamin K antagonists, heparin, direct thrombin and factor Xa inhibitors have in common that they target key proteins of the haemostatic system. In an attempt to overcome these difficulties we investigated whether the intrinsic coagulation factors (VIII, IX, XI, XII, prekallikrein and high-molecular-weight kininogen) are superior targets for anticoagulation. We analysed epidemiological data concerning thrombosis and bleeding in patients deficient in one of the intrinsic pathway proteins. Furthermore, we discuss several thrombotic models in intrinsic coagulation factor-deficient animals. The combined results suggest that intrinsic coagulation factors could be suitable targets for anticoagulant drugs.

Molecular diagnosis of factor XIII deficiency, data from comprehensive coagulation laboratory in Iran

: Diagnosis of factor XIII (FXIII) deficiency (FXIIID) as a rare bleeding disorder is a challenge worldwide. Thus, in the present study, we used different methods including two molecular methods for detection of FXIIID. This study was conducted on individuals suspected to FXIIID. All individuals were checked by two routinely used methods of clot solubility test in Iran and two other clot solubility tests as well as FXIII activity and antigen assays. Molecular analysis was performed by PCR-restriction fragment length polymorphism (PCR-RFLP) and tetra-primer amplification refractory mutation system (T-ARMS)-PCR for only FXIIID mutation in southeast Iran (p.Trp187Arg), previously associated with severe FXIIID. Out of 151 individuals, 26 had abnormal clot solubility test with all four methods. PCR-RFLP revealed that 27 patients were homozygotes for p.Trp187Arg, whereas 12 were heterozygotes. Molecular analysis revealed that in routinely used clot solubility combinations, two homozygotes (∼8%) were missed, whereas in two other combinations, one patient (∼4%) was missed. One false positive result was observed in routinely used methods, whereas further combinations don't have false positive. T-ARMS-PCR had three discrepancies with PCR-RFLP and sequencing confirmed that the results of T-ARMS-PCR were false. FXIII antigen assay diagnosed all homozygotes, whereas in FXIII activity assay, two homozygotes had higher than 5% FXIII activity that inconsistent with severe deficiency. It seems that clot solubility test is not enough sensitive and specific and molecular analysis is the most reliable method for detection of FXIIID in areas such Iran with one or few specific mutations.

Maternal and foetal outcomes following natural vaginal versus caesarean section (c-section) delivery in women with bleeding disorders and carriers

BACKGROUND

Bleeding disorders are uncommon but may pose significant bleeding complications during pregnancy, labour and following delivery for both the woman and the foetus. While many bleeding disorders in women tend to improve in pregnancy, thus decreasing the haemorrhagic risk to the mother at the time of delivery, some do not correct or return quite quickly to their pre-pregnancy levels in the postpartum period. Therefore, specific measures to prevent maternal bleeding and foetal complications during childbirth, are required. The safest method of delivery to reduce morbidity and mortality in these women is controversial. This is an update of a previously published review.

OBJECTIVES

To assess the optimal mode of delivery in women with, or carriers of, bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the Cochrane Pregnancy and Childbirth Group's Trials Register as well as trials registries and the reference lists of relevant articles and reviews.Date of last search of the Group's Trials Registers: 16 February 2017.

SELECTION CRITERIA

Randomised controlled trials and all types of controlled clinical trials investigating the optimal mode of delivery in women with, or carriers of, any type of bleeding disorder during pregnancy were eligible for the review.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion MAIN RESULTS: No results from randomised controlled trials were found.

AUTHORS' CONCLUSIONS

The review did not identify any randomised controlled trials investigating the safest mode of delivery and associated maternal and foetal complications during delivery in women with, or carriers of, a bleeding disorder. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials, case studies) to decide upon the optimal mode of delivery to ensure the safety of both mother and foetus.Given the ethical considerations, the rarity of the disorders and the low incidence of both maternal and foetal complications, future randomised controlled trials to find the optimal mode of delivery in this population are unlikely to be carried out. Other high quality controlled studies (such as risk allocation designs, sequential design, and parallel cohort design) are needed to investigate the risks and benefits of natural vaginal and caesarean section in this population or extrapolation from other clinical conditions that incur a haemorrhagic risk to the baby, such as platelet alloimmunisation.

Reaction-diffusion waves of blood coagulation

One of the main characteristics of blood coagulation is the speed of clot growth. In the current work we consider a mathematical model of the coagulation cascade and study existence, stability and speed of propagation of the reaction-diffusion waves of blood coagulation. We also develop a simplified one-equation model that reflects the main features of the thrombin wave propagation. For this equation we estimate the wave speed analytically. The resulting formulas provide a good approximation for the speed of wave propagation in a more complex model as well as for the experimental data.

Molecular genetic analysis of the F11 gene in 14 Turkish patients with factor XI deficiency: identification of novel and recurrent mutations and their inheritance within families

BACKGROUND

Factor XI (FXI) deficiency is an autosomal bleeding disease associated with genetic defects in the F11 gene which cause decreased FXI levels or impaired FXI function. An increasing number of mutations has been reported in the FXI mutation database, most of which affect the serine protease domain of the protein. FXI is a heterogeneous disorder associated with a variable bleeding tendency and a variety of causative F11 gene mutations. The molecular basis of FXI deficiency in 14 patients from ten unrelated families in Turkey was analysed to establish genotype-phenotype correlations and inheritance of the mutations in the patients' families.

MATERIAL AND METHODS

Fourteen index cases with a diagnosis of FXI deficiency and family members of these patients were enrolled into the study. The patients' F11 genes were amplified by polymerase chain reaction and subjected to direct DNA sequencing analysis. The findings were analysed statistically using bivariate correlations, Pearson's correlation coefficient and the nonparametric Mann-Whitney test.

RESULTS

Direct DNA sequencing analysis of the F11 genes revealed that all of the 14 patients had a F11 gene mutation. Eight different mutations were identified in the apple 1, apple 2 or serine protease domains, except one which was a splice site mutation. Six of the mutations were recurrent. Two of the mutations were novel missense mutations, p.Val522Gly and p.Cys581Arg, within the catalytic domain. The p.Trp519Stop mutation was observed in two families whereas all the other mutations were specific to a single family.

DISCUSSION

Identification of mutations confirmed the genetic heterogeneity of FXI deficiency. Most of the patients with mutations did not have any bleeding complications, whereas some had severe bleeding symptoms. Genetic screening for F11 gene mutations is important to decrease the mortality and morbidity rate associated with FXI deficiency, which can be life-threatening if bleeding occurs in tissues with high fibrinolytic activity.

Von Willebrand Factor Antigen and Factor XI Activity Levels As Predictors of Bleeding Tendency in Israeli Patients with Von Willebrand's Disease

Previous preliminary data and case reports have suggested an association of von Willebrand's disease (vWD) with factor XI deficiency and platelet abnormalities. We have analyzed the prevalence of factor XI deficiency and thrombocytopathy in a cohort of Israeli patients with vWD. Decreased factor XI levels (<67 U/dl) were documented in 35 of 63 (36%) vWD subjects; factor XI levels were <30 U/dl in five of 60 (8%). A significant decline in ADP-induced platelet aggregation (<30% of control) was found in 48% of vWD patients. Likewise, epinephrine-induced aggregation was reduced in 41%, and collagen-induced aggregation was decreased in 7% of vWD patients. Logistic regression analysis showed that while Ivy bleeding time, ristocetin cofactor, and ristocetin-induced platelet aggregation did not predict bleeding, both von Willebrand factor antigen and factor XI activity levels predict bleeding in patients with vWD. These findings suggest that mild factor XI deficiency and thrombocytopathy are common in Israeli subjects with vWD and that associated factor XI deficiency can result in clinical bleeding in these patients. Key Words: Von Willebrand' s disease—Factor XI deficiency—Thrombocytopathy.

One case of rare gastric cancer combined with lack of factor XI

The patient, a 50-year-old woman, was admitted to hospital diagnosed with gastric cancer. While performing preoperative examination, we found that this patient had a lack of factor XI. This is the first case diagnosed with gastric cancer combined with lack of emitted factor XI, at least in China. We used only fresh frozen plasma to correct the blood coagulation disorder to perform an operation. Firstly, we think this is a rare case that should be reported. Secondly, what we have done to help this patient may help other doctors to make decisions when they meet any similar cases.

Desmopressin acetate (DDAVP) for preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders

BACKGROUND

Congenital bleeding disorders can cause obstetric haemorrhage during pregnancy, labour and following delivery. Desmopressin acetate is found to be an effective drug which can reduce the risk of haemorrhage and can also stop bleeding in certain congenital bleeding disorders. Its use in pregnancy has been controversial. Hence beneficial and adverse effects of desmopressin acetate in these groups of pregnant women should be evaluated.This is an update of a Cochrane review first published in 2013.

OBJECTIVES

To determine the efficacy of desmopressin acetate in preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant and abstract books of conferences proceedings. We also searched for any randomised controlled trials in a registry of ongoing trials and the reference lists of relevant articles and reviews.Date of most recent search: 18 June 2015.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials investigating the efficacy of desmopressin acetate versus tranexamic acid or factor VIII or rFactor VII or fresh frozen plasma in preventing and treating congenital bleeding disorders during pregnancy were eligible.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No trials matching the selection criteria were eligible for inclusion.

AUTHORS' CONCLUSIONS

The review did not identify any randomised controlled trials investigating the relative effectiveness of desmopressin acetate for bleeding during pregnancy in women with congenital bleeding disorders. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials) to decide whether or not to treat women with congenital bleeding disorders with desmopressin acetate.Given the ethical considerations, future randomised controlled trials are unlikely. However, other high quality controlled studies (such as risk allocation designs, sequential design, parallel cohort design) to investigate the risks and benefits of using desmopressin acetate in this population are needed.

Sample conditions determine the ability of thrombin generation parameters to identify bleeding phenotype in FXI deficiency

Individuals with Factor XI (FXI) deficiency have a variable bleeding tendency that does not correlate with FXI:C levels or genotype. Comparing a range of sample conditions, we tested whether the thrombin generation assay (TGA) could discriminate between control subjects (n = 50) and FXI-deficient individuals (n = 97), and between those with bleeding tendency (n = 50) and without (n = 24). The comparison used platelet-rich plasma (PRP) and platelet-poor plasma (PPP), either with or without corn trypsin inhibitor (CTI) to prevent contact activation, over a range of tissue factor (TF) concentrations. When contact activation was inhibited and platelets were absent, FXI:C levels did not correlate with thrombin generation parameters, and control and FXI-deficient individuals were not distinguished. In all other sample types, the best discrimination was obtained using TF 0.5 pM and assay measures: endogenous thrombin potential (ETP) and peak height. We showed that although a number of conditions could distinguish differences between the groups tested, TGA measured in PRP with CTI best differentiated between bleeders and nonbleeders. These measures provided high sensitivity and specificity (peak height receiver operating characteristic [ROC] area under the curve [AUC] = 0.9362; P < .0001) (ETP ROC AUC = 0.9362; P < .0001). We conclude that by using sample conditions directed to test specific pathways of FXI activation, the TGA can identify bleeding phenotype in FXI deficiency.

Maternal and foetal outcomes following natural vaginal versus caesarean section (c-section) delivery in women with bleeding disorders and carriers

BACKGROUND

Bleeding disorders are uncommon but may pose significant bleeding complications during pregnancy, labour and following delivery for both the woman and the foetus. While many bleeding disorders in women tend to improve in pregnancy, thus decreasing the haemorrhagic risk to the mother at the time of delivery, some do not correct or return quite quickly to their pre-pregnancy levels in the postpartum period. Therefore, specific measures to prevent maternal bleeding and foetal complications during childbirth, are required. The safest method of delivery to reduce morbidity and mortality in these women is controversial.

OBJECTIVES

To assess the optimal mode of delivery in women with, or carriers of, bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the Cochrane Pregnancy and Childbirth Group's Trials Register as well as trials registries and the reference lists of relevant articles and reviews.Date of last search of the Group's Trials Registers: 13 January 2015.

SELECTION CRITERIA

Randomised controlled trials and all types of controlled clinical trials investigating the optimal mode of delivery in women with, or carriers of, any type of bleeding disorder during pregnancy were eligible for the review.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion

MAIN RESULTS

No results from randomized controlled trials were found.

AUTHORS' CONCLUSIONS

The review did not identify any randomised controlled trials investigating the safest mode of delivery and associated maternal and foetal complications during delivery in women with, or carriers of, a bleeding disorder. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials, case studies) to decide upon the optimal mode of delivery to ensure the safety of both mother and foetus.Given the ethical considerations, the rarity of the disorders and the low incidence of both maternal and foetal complications, future randomised controlled trials to find the optimal mode of delivery in this population are unlikely to be carried out. Other high quality controlled studies (such as risk allocation designs, sequential design, and parallel cohort design) are needed to investigate the risks and benefits of natural vaginal and caesarean section in this population or extrapolation from other clinical conditions that incur a haemorrhagic risk to the baby, such as platelet alloimmunisation.

Factor XI deficiency and orthognathic surgery: a case report on anesthesia management

Factor XI deficiency (Hemophilia C) is a very rare autosomal recessive bleeding disorder. Patients with factor XI deficiency do not typically show any spontaneous bleeding or specific symptoms. Sometimes those who have this disorder are identified during special situations such as trauma or surgery. Orthognathic surgery is particularly associated with a high bleeding risk. Therefore, great care must be taken when treating patients with bleeding disorders such as factor XI deficiency. There are a few reports that address the management of patients with bleeding disorders during orthognathic surgery. The current report describes a patient with factor XI deficiency who underwent Le Fort I osteotomy together with bilateral sagittal split osteotomy. The patient's condition was assessed using both rotation thromboelastometry (ROTEM™) and noninvasive measurements of total hemoglobin (SpHb) using Masimo Radical 7 (Masimo Co. CA, USA).

Novel insights into the molecular pathogenesis of CYP4V2-associated Bietti's retinal dystrophy

Bietti's crystalline dystrophy (BCD) is a rare, autosomal recessive retinal degenerative disease associated with mutations in CYP4V2. In this study, we describe the genetic and clinical findings in 19 unrelated BCD patients recruited from five international retinal dystrophy clinics. Patients underwent ophthalmic examinations and were screened for CYP4V2 mutations by Sanger sequencing and quantitative polymerase chain reaction (qPCR) copy number variation screening. Eight CYP4V2 mutations were found in 10/19 patients, including three patients in whom only monoallelic mutations were detected. Four novel mutations were identified: c.604G>A; p.(Glu202Lys), c.242C>G; p.(Thr81Arg), c.604+4A>G; p.(?), and c.1249dup; p.(Thr417Asnfs*2). In addition, we identified a heterozygous paternally inherited genomic deletion of at least 3.8 Mb, encompassing the complete CYP4V2 gene and several other genes, which is novel. Clinically, patients demonstrated phenotypic variability, predominantly showing choroidal sclerosis, attenuated vessels, and crystalline deposits of varying degrees of severity. To our knowledge, our study reports the first heterozygous CYP4V2 deletion and hence a novel mutational mechanism underlying BCD. Our results emphasize the importance of copy number screening in BCD. Finally, the identification of CYP4V2-negative patients with indistinguishable phenotypes from CYP4V2-positive patients might suggest the presence of mutations outside the coding regions of CYP4V2, or locus heterogeneity, which is unreported so far.

Abnormal plasma clot structure and stability distinguish bleeding risk in patients with severe factor XI deficiency

BACKGROUND

Factor XI (FXI) deficiency is a rare autosomal recessive disorder. Many patients with even very low FXI levels (< 20 IU dL(-1) ) are asymptomatic or exhibit only mild bleeding, whereas others experience severe bleeding, usually following trauma. Neither FXI antigen nor activity predicts the risk of bleeding in FXI-deficient patients.

OBJECTIVES

(i) Characterize the formation, structure and stability of plasma clots from patients with severe FXI deficiency and (ii) determine whether these assays can distinguish asymptomatic patients ('non-bleeders') from those with a history of bleeding ('bleeders').

METHODS

Platelet-poor plasmas were prepared from 16 severe FXI-deficient patients who were divided into bleeders or non-bleeders, based on bleeding associated with at least two tooth extractions without prophylaxis. Clot formation was triggered by recalcification and addition of tissue factor and phospholipids in the absence or presence of tissue plasminogen activator and/or thrombomodulin. Clot formation and fibrinolysis were measured by turbidity and fibrin network structure by laser scanning confocal microscopy.

RESULTS

Non-bleeders and bleeders had similarly low FXI levels, normal prothrombin times, normal levels of fibrinogen, factor VIII, von Willebrand factor and factor XIII, and normal platelet number and function. Compared with non-bleeders, bleeders exhibited lower fibrin network density and lower clot stability in the presence of tissue plasminogen activator. In the presence of thrombomodulin, seven of eight bleeders failed to form a clot, whereas only three of eight non-bleeders did not clot.

CONCLUSIONS

Plasma clot structure and stability assays distinguished non-bleeders from bleeders. These assays may reveal hemostatic mechanisms in FXI-deficient patients and have clinical utility for assessing the risk of bleeding.

The spectrum of factor XI deficiency in Italy

Factor XI (FXI) deficiency is a rare inherited bleeding disorder invariably caused by mutations in the FXI gene. The disorder is rather frequent in Ashkenazi Jews, in whom around 98% of the abnormal alleles is represented by Glu117X and Phe283Leu mutations. A wide heterogeneity of causative mutations has been previously reported in a few FXI deficient patients from Italy. In this article, we enlarge the knowledge on the genetic background of FXI deficiency in Italy. Over 4 years, 22 index cases, eight with severe deficiency and 14 with partial deficiency, have been evaluated. A total of 21 different mutations in 30 disease-associated alleles were identified, 10 of which were novel. Among them, a novel Asp556Gly dysfunctional mutation was also identified. Glu117X was also detected, as previously reported from other patients in Italy, while again Phe283Leu was not identified. A total of 34 heterozygous relatives were also identified. Bleeding tendency was present in very few cases, being inconsistently related to the severity of FXI deficiency in plasma. In conclusion, at variance with other populations, no single major founder effect is present in Italian patients with FXI deficiency.

Desmopressin acetate (DDAVP) for preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders

BACKGROUND

Congenital bleeding disorders can cause obstetric haemorrhage during pregnancy, labour and following delivery. Desmopressin acetate is found to be an effective drug which can reduce the risk of haemorrhage and can also stop bleeding in certain congenital bleeding disorders. Its use in pregnancy has been controversial. Hence beneficial and adverse effects of desmopressin acetate in these groups of pregnant women should be evaluated.

OBJECTIVES

To determine the efficacy of desmopressin acetate in preventing and treating acute bleeds during pregnancy in women with congenital bleeding disorders.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coaguopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant and abstract books of conferences proceedings. We also searched for any randomised controlled trials in a registry of ongoing trials and the reference lists of relevant articles and reviews.Date of most recent search: 28 February 2013.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials investigating the efficacy of desmopressin acetate versus tranexamic acid or factor VIII or rFactor VII or fresh frozen plasma in preventing and treating congenital bleeding disorders during pregnancy were eligible.

DATA COLLECTION AND ANALYSIS

No trials matching the selection criteria were eligible for inclusion.

MAIN RESULTS

No trials matching the selection criteria were eligible for inclusion.

AUTHORS' CONCLUSIONS

The review did not identify any randomised controlled trials investigating the relative effectiveness of desmopressin acetate for bleeding during pregnancy in women with congenital bleeding disorders. In the absence of high quality evidence, clinicians need to use their clinical judgement and lower level evidence (e.g. from observational trials) to decide whether or not to treat women with congenital bleeding disorders with desmopressin acetate.Given the ethical considerations, future randomised controlled trials are unlikely. However, other high quality controlled studies (such as risk allocation designs, sequential design, parallel cohort design) to investigate the risks and benefits of using desmopressin acetate in this population are needed.

Inherited bleeding disorders in pregnancy

Women with inherited bleeding disorders may face several haemostatic challenges during pregnancy and childbirth. Pregnancy in these women requires specialised and individualised care. Prenatal diagnosis is primarily considered in families affected by severe bleeding disorder such as haemophilia. Non-invasive fetal sex determination by analysis of free fetal DNA in maternal blood offers carriers of haemophilia a means of avoiding invasive testing and its associated risks in female pregnancies. With the exception of fibrinogen and factor XIII deficiencies, it is currently unclear whether women with inherited bleeding disorders are at increased risk of miscarriage or antepartum haemorrhage. However, they are at increased risk of primary and secondary postpartum haemorrhage. The fetus, if severely affected, is at risk of cranial bleeding during labour and delivery. Appropriate haemostatic cover during labour and delivery, avoidance of prolonged labour and traumatic delivery, and active management of third stage of labour can minimise the risk of bleeding complications for the mother and her fetus.

Factor deficiencies in pregnancy

Pregnancy, childbirth, and the puerperium are hemostatically challenging to women with bleeding disorders. This article provides general recommendations for the management of pregnant women with inherited coagulation disorders. Each factor deficiency is discussed, providing an up-to-date review of the literature and, where possible, guidance about how to manage patients throughout pregnancy, delivery, and the puerperium. The factor deficiencies covered are inherited abnormalities of fibrinogen; deficiencies of prothrombin, factor (F)V, FVII, FX, FXI, FXIII; combined deficiencies of FV and FVIII; and the inherited deficiency of vitamin K-dependent clotting factors. The management of carriers of hemophilia A and B is also discussed.