Off-the-shelf cryopreserved platelets for the detection of HIT and VITT antibodies.

Heparin-induced thrombocytopenia (HIT) is suspected much more often than it is confirmed. Technically simple platelet factor 4 (PF4)-polyanion enzyme-linked immunosorbent assays (ELISAs) are sensitive but nonspecific. In contrast, accurate functional tests such as the serotonin release assay, heparin-induced platelet activation assay, and PF4-dependent P-selectin expression assay require fresh platelets and have complex assay end points, limiting their availability to specialized reference laboratories. To enable broad deployment of functional testing, we sought to extend platelet viability significantly by optimizing storage conditions and developed a simple functional assay end point by measuring the release of a platelet α-granule protein, thrombospondin-1 (TSP1), in an ELISA format. Platelet cryopreservation conditions were optimized by freezing platelets at controlled cooling rates that preserve activatability. Several-month-old cryopreserved platelets were treated with PF4 or heparin and were evaluated for their ability to be activated by HIT and vaccine-induced immune thrombotic thrombocytopenia (VITT) antibodies in the TSP1 release assay (TRA). HIT and spontaneous HIT patient samples induced significantly higher TSP1 release using both PF4-treated (PF4-TRA) and heparin-treated cryopreserved platelets relative to samples from patients suspected of HIT who lacked platelet-activating antibodies. This latter group included several patients that tested strongly positive in PF4-polyanion ELISA but were not platelet-activating. Four VITT patient samples tested in the TRA activated PF4-treated, but not heparin-treated, cryopreserved platelets, consistent with recent data suggesting the requirement for PF4-treated platelets for VITT antibody detection. These findings have the potential to transform the testing paradigm in HIT and VITT, making decentralized, technically simple functional testing available for rapid and accurate in-hospital diagnosis.

Use of crushed tranexamic acid tablets in water for paediatric patients with bleeding disorders.

BACKGROUND: Ε-Aminocaproic acid oral solution (EACA OS) is the only commercially available antifibrinolytic for patients who cannot swallow tablets. Insurance denials and high costs remain barriers to its use. OBJECTIVES: To determine the safety and efficacy of crushed tranexamic acid tablets in water (cTXAw) for children with bleeding disorders. METHODS: We retrospectively reviewed records of children (<10 years) with bleeding disorders who received cTXAw or EACA OS from 1 December 2018, through 31 July 2022, at Mayo Clinic (Rochester, Minnesota). Bleeding outcomes were defined according to ISTH criteria. RESULTS: Thirty-two patients were included (median age, 3 years; male, n = 23). Diagnoses were VWD (n = 17), haemophilia (n = 5), FVII deficiency (n = 3), inherited platelet disorder (n = 4), ITP (n = 2), and combined FV and FVII deficiencies (n = 1). Thirty-two courses of cTXAw (monotherapy 24/32; mean duration 6 days) and fifteen courses of EACA (monotherapy 12/15; mean duration 5 days) were administered. No surgical procedures (n = 28) were complicated by bleeding. Of the 19 bleeding events, 16 had effective haemostasis, two had no reported outcome, and one had no response. cTXAw and EACA were equally effective in preventing and treating bleeding (p value > .1). No patients had adverse effects. Eight of 19 patients (42%) who were initially prescribed EACA OS did not receive it because of cost or insurance denial. The estimated average wholesale price of one treatment was $94 for cTXAw and $905 for EACA OS. CONCLUSIONS: CTXAw appears to be an effective, safe, and low-cost alternative option to EACA OS for young children with bleeding disorders.

The Use of Bypassing Treatment Strategies in Hemophilia and Their Effect on Laboratory Testing.

Factor VIII and IX inhibitors in congenital hemophilia A and B, respectively, neutralize the infused coagulation factor concentrate rendering them ineffective. Bypassing agents (BPAs) that circumvent the block imposed by the inhibitors are used for the prevention and management of bleeding. Activated prothrombin complex concentrate was the original BPA, recombinant activated factor VII was then introduced, and more recently nonfactor agents that target the procoagulant and anticoagulant systems have been developed and are in clinical use (e.g., emicizumab, a bispecific antibody for hemophilia A). Other BPAs are in clinical trials (e.g., fitusiran targets antithrombin, concizumab and marstacimab target tissue factor pathway inhibitor, and SerpinPC targets activated protein C). The BPAs have a varied effect on coagulation assays, and as more patients are exposed to these agents, it is important to be aware of the effects. Herein, we present an overview of the effect of BPAs on routine and specialized coagulation assays including thrombin generation and viscoelastic assays.

Von Willebrand Factor Multimer Analysis and Classification: A Comprehensive Review and Updates.

Von Willebrand factor (VWF) is a multimeric glycoprotein with essential roles in primary hemostasis. Patients with von Willebrand disease (VWD), due to quantitative and/or qualitative defects of VWF usually experience mucocutaneous bleeding. Based on the laboratory results of VWF antigen, various VWF activities, factor VIII activity, and VWF multimer patterns, VWD can be categorized as type 1, 2, and 3 VWD. VWF multimer analysis by either manual or semi-automated electrophoresis and immunoblotting is a critical part of the laboratory testing to differentiate type 1, type 2 VWD, and subtypes of type 1 or 2 VWD. The multimer distribution patterns can also help to understand the underlying molecular mechanism of VWF synthesis, multimerization, and clearance defects in VWD. This review will cover VWF synthesis, multimerization, secretion, VWF multimer analysis, and VWF multimer interpretation of various types and subtypes of VWD.

A prospective, blinded study of a PF4-dependent assay for HIT diagnosis.

Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14-labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.

Risk of thrombosis in women with cancer undergoing controlled ovarian hyperstimulation for fertility preservation.

PURPOSE: The study aims to evaluate the risk factors and incidence of thromboembolic events among adult women with cancer who underwent controlled ovarian hyperstimulation (COH) for fertility preservation. METHODS: Retrospective, descriptive cohort analysis of patient demographics, medical history, cancer type/treatment, laboratory values, thrombosis within 6 months of COH. RESULTS: 4 of 127 study participants experienced a venous thromboembolic event within 6 months of COH. The median time between oocyte aspiration and the event was 0.25 years (range = 0.10-0.50). The average age at time of event was 25.3 years (SD = 5.3). Three of four thrombotic patients had ovarian cancer, one had breast cancer. All had received surgery and chemotherapy for treatment. All underwent an antagonist cycle ovarian stimulation protocol - none developed ovarian hyperstimulation syndrome. The average anti-mullerian hormone level at the time of hyperstimulation in the thrombosis group was 1.6 (SD = 1.3), compared to 3.6 in the non-thrombosis group. The average max estradiol level reached during ovarian stimulation was 1281.3 (SD = 665.3) in the thrombosis group and 1839.1 (SD = 1513.9) in the non-thrombosis group. Thromboembolic events were not directly associated with mortality. CONCLUSIONS: Within this small descriptive study, the incidence of thromboembolic events in women with cancer undergoing COH for fertility preservation is high. Cancer may play a greater role than COH in thrombosis risk. Ovarian cancer patients who undergo ovarian stimulation may have an increased risk compared to other cancer types. These findings may inform future, prospective studies to determine the role of thromboprophylaxis.

Cerebral venous sinus thrombosis associated with spontaneous heparin-induced thrombocytopenia syndrome after total knee arthroplasty.

Spontaneous heparin-induced thrombocytopenia (HIT) syndrome, characterized by clinical and serologic features of HIT despite the absence of proximate heparin exposure, can be triggered by total knee arthroplasty (TKA). A 56-year-old female receiving aspirin thromboprophylaxis post-TKA presented with aphasia and thrombocytopenia on post-operative day 11. Imaging studies revealed cerebral venous sinus thrombosis (CVST) and intravenous bivalirudin was initiated. Her serum tested strong-positive for IgG anti-PF4/polyanion complexes and serotonin-release assay in the presence and absence of heparin; strong-positive IgG-specific chemiluminescent immunoassay; and moderate-positive latex immunoturbidimetric assay. Two 65 g doses of IVIG were administered. With the improvement of her platelet count, she was transitioned from bivalirudin to warfarin. At one-year follow-up, she remained free of recurrent thrombosis and neurologically stable with a normal platelet count. Previous reports of post-TKA spontaneous HIT syndrome include venous/arterial thrombosis and adrenal hemorrhage, and this report of CVST expands the clinical spectrum of this rare complication of orthopedic surgery.

Hemostatic prophylaxis and colonoscopy outcomes for patients with bleeding disorders: A retrospective cohort study and review of the literature.

INTRODUCTION: Hemostatic prophylaxis (HP) is recommended for patients with bleeding disorders (PWBD) before invasive procedures. However, evidence-based guidelines are needed to determine optimal HP strategies. AIM: To determine outcomes of HP for PWBD undergoing colonoscopy. METHODS: We undertook a retrospective cohort study of HP and outcomes of colonoscopy procedures performed between 9 November 1993 and 13 February 2018 for PWBD who received care in the Mayo Clinic Comprehensive Hemophilia Treatment Center. RESULTS: During the study period, 73 PWBD (58 with milder phenotypes: haemophilia, von Willebrand disease [subtypes 1 and 2; II, VII and XI deficiency]) underwent 141 procedures. Preprocedural HP was given to 61%, and interventions were performed in 47%. Of the 39% without preprocedural HP, postprocedural HP was given for 11%. One major (0.7%; 6 days postprocedure despite HP) and 10 minor (7%) bleeding complications occurred, which tended to be in patients with severe disease and/or after excision of larger polyps. There was no significant difference in the rate of bleeding complications with or without preprocedural HP (8.1% vs 5.5%, respectively; P = .74, Fisher's exact test). CONCLUSION: The low bleeding rates in our cohort suggest that preprocedure HP may be withheld for patients with mild bleeding disorders who undergo colonoscopy with a low likelihood of requiring an intervention or who require only low-risk intervention. This strategy may be best used in experienced centres, provided optimal local hemostasis measures are undertaken and postprocedural HP is rapidly available if high-risk intervention is required. Further studies are needed to determine optimal evidence-based HP strategies for PWBD undergoing colonoscopy.

Factor IX Gene (F9) Genotyping Trends and Spectrum of Mutations Identified: A Reference Laboratory Experience.

In hemophilia B (HB), factor IX gene (F9) genotyping is used for molecular confirmation of affected individuals, for carrier testing, to facilitate the identification of those at risk for anaphylaxis/inhibitors (associated with large deletions), and to assist in assigning disease severity. Owing to test costs, optimal test utilization involves pre/post-test counseling and appropriate patient and test selection (e.g., mutation screening [F9MS] vs. known mutation [F9KM] testing). This article aims to review the trends and outcomes of F9-genotyping orders and describe the spectrum of variants identified in a sample of individuals in our reference laboratory. We performed a retrospective review of consecutive orders submitted to the Special Coagulation DNA Diagnostic Laboratory, Mayo Clinic, between 2012 and 2015. A total of 133 orders (38%) were identified for men: 118 (88%) were F9MS and 15 (12%) were F9KM. Thirteen orders (10%) were cancelled. A total of 209 orders were identified for women: 178 (85%) were F9MS and 31 (15%) were F9KM. Thirty-seven orders (18%) were cancelled and 30% of the tests performed yielded negative results. A total of 164 samples (47%) were received without clinical information. Seventeen previously unreported variants were identified. F9 genotyping provides useful information for HB management; however, 18% of our orders were cancelled and almost half were received without relevant clinical information, thus reaffirming the need for ongoing scrutiny of submitted orders. Optimal patient and test selection is important as is the accurate interpretation of variants identified. Most of the pathogenic variants identified were point mutations, with very few large deletions, consistent with the literature.

Hermansky-Pudlak syndrome subtype 5 (HPS-5) novel mutation in a 65 year-old with oculocutaneous hypopigmentation and mild bleeding diathesis: The importance of recognizing a subtle phenotype.

Hermansky-Pudlak syndrome (HPS) - characterized by the distinct clinical phenotypes of both oculocutaneous albinism and mild bleeding diathesis-is caused by mutations in genes that have crucial roles in the assembly of cellular organelles (skin melanosomes, platelet delta [dense] granules, lung lamellar bodies, and cytotoxic T-cell lymphocyte granules). Immunodeficiency, pulmonary fibrosis and granulomatous colitis are associated with some, but not all subtypes of HPS, with varying degrees of clinical severity. We describe a patient diagnosed with platelet dense granule storage pool deficiency (DG-SPD) at age 38 years after he presented with spontaneous intracranial hemorrhage. His mild oculocutaneous hypopigmentation was subtle. In the following 27 years, he did not develop severe bleeding nor pulmonary or gastrointestinal complications. A novel homozygous c.1960A>T; p.Lys654* mutation in the HPS-5 protein gene (HPS5) was identified through next generation sequencing, (NGS) which is consistent with the patient's clinical and laboratory phenotypes. This case underscores the importance of recognizing the mild clinical phenotype of HPS-5 and utilization of both laboratory and molecular testing for diagnosis, prognostication, and surveillance for end organ damage in patients affected with HPS.

Diagnostic laboratory standardization and validation of platelet transmission electron microscopy.

Platelet transmission electron microscopy (PTEM) is considered the gold standard test for assessing distinct ultrastructural abnormalities in inherited platelet disorders (IPDs). Nevertheless, PTEM remains mainly a research tool due to the lack of standardized procedures, a validated dense granule (DG) count reference range, and standardized image interpretation criteria. The aim of this study was to standardize and validate PTEM as a clinical laboratory test. Based on previously established methods, we optimized and standardized preanalytical, analytical, and postanalytical procedures for both whole mount (WM) and thin section (TS) PTEM. Mean number of DG/platelet (plt), percentage of plts without DG, platelet count (PC), mean platelet volume (MPV), immature platelet fraction (IPF), and plt light transmission aggregometry analyses were measured on blood samples from 113 healthy donors. Quantile regression was used to estimate the reference range for DG/plt, and linear regression was used to assess the association of DG/plt with other plt measurements. All PTEM procedures were standardized using commercially available materials and reagents. DG interpretation criteria were established based on previous publications and expert consensus, and resulted in improved operator agreement. Mean DG/plt was stable for 2 days after blood sample collection. The median within patient coefficient of variation for mean DG/plt was 22.2%; the mean DG/plt reference range (mid-95th %) was 1.2-4.0. Mean DG/plt was associated with IPF (p = .01, R2 = 0.06) but not age, sex, PC, MPV, or plt maximum aggregation or primary slope of aggregation (p > .17, R2 < 0.02). Baseline ultrastructural features were established for TS-PTEM. PTEM was validated using samples from patients with previously established diagnoses of IPDs. Standardization and validation of PTEM procedures and interpretation, and establishment of the normal mean DG/plt reference range and PTEM baseline ultrastructural features, will facilitate implementation of PTEM as a valid clinical laboratory test for evaluating ultrastructural abnormalities in IPDs.

The impact of postpartum hemorrhage on hospital length of stay and inpatient mortality: a National Inpatient Sample-based analysis.

BACKGROUND: Postpartum hemorrhage is a major cause of maternal morbidity and mortality, but the association between postpartum hemorrhage and hospital length of stay has not been rigorously investigated. OBJECTIVE: We explored the impact of postpartum hemorrhage on hospital length of stay and inpatient mortality, as these outcomes have both clinical and economic significance. STUDY DESIGN: We performed a retrospective analysis using data from the National Inpatient Sample database during the 2012 through 2013 time period. Deliveries were classified as postpartum hemorrhage due to uterine atony, nonatonic postpartum hemorrhage, or not complicated by postpartum hemorrhage (nonpostpartum hemorrhage). Average length of stay and inpatient mortality rates were compared between groups. RESULTS: Over the study interval, postpartum hemorrhage occurred in 3% of deliveries. Among deliveries complicated by postpartum hemorrhage, 76.6% were attributed to uterine atony and 23.4% were nonatonic. Women with nonatonic postpartum hemorrhage had the highest average length of stay (3.67 days) followed by atonic postpartum hemorrhage (2.98 days) and nonpostpartum hemorrhage (2.63 days); P < .001, all comparisons. Inpatient mortality rate of nonatonic postpartum hemorrhage over the entire study period was 104 per 100,000 compared to 019 per 100,000 for atonic postpartum hemorrhage and 3 per 100,000 for nonpostpartum hemorrhage deliveries (P < .001). CONCLUSION: From 2012 through 2013, women with postpartum hemorrhage experienced significantly longer length of stay and higher inpatient mortality rates than women without postpartum hemorrhage, largely attributable to nonatonic causes of postpartum hemorrhage. As hospital length of stay and inpatient mortality are important outcomes from both clinical and societal perspectives, interventions to reduce morbidity and mortality related to postpartum hemorrhage may simultaneously facilitate delivery of more cost-effective care and improve both maternal and population health.

Sex-based disparities in venous thromboembolism outcomes: A National Inpatient Sample (NIS)-based analysis.

Venous thromboembolism (VTE) contributes to significant morbidity, mortality, and socioeconomic burden. There is a paucity of literature regarding sex-based sociodemographic differences in VTE presentation and short-term outcomes. We aimed to compare clinical outcomes between men and women hospitalized for VTE management. We performed a retrospective analysis using data from the National Inpatient Sample (NIS) database from 2012 to 2013. Inclusion criteria were age 18 years and older and a primary discharge diagnosis of VTE. Sociodemographic features and medical comorbidities were analyzed, as were hospital length of stay and in-hospital mortality rates. A total of 107,896 patients met the inclusion criteria; 53% were female. Median age was 65 years (interquartile range 51-77) and women were older than men (65 vs 62 years, p<0.001). There were significant differences between men and women with respect to race, primary insurance payer and medical comorbidities, and small differences with respect to VTE location. Female sex was associated with a small but significantly longer hospital length of stay (mean ratio 1.04, 95% CI 1.03-1.05, p<0.001) but no significant difference in in-hospital mortality (2.2% vs 2.1%, p=0.15). In a multivariate model, there was no significant difference between women and men with respect to hospital length of stay or in-hospital mortality. In conclusion, we used data from the NIS to study over 100,000 patients hospitalized for VTE, and identified several sex-based disparities in sociodemographic factors and location of VTE. However, in a multivariable analysis correcting for these factors, sex was not associated with significant differences in clinical outcomes.

Therapeutic plasma exchange for perioperative management of patients with congenital factor XI deficiency.

BACKGROUND: Factor XI (FXI) deficiency (hemophilia C [HEM-C]) is a bleeding disorder with unpredictable severity that correlates poorly with FXI coagulation activity (FXI:C). It poses a perioperative hemostatic management challenge. For US patients with severe disease, fresh frozen plasma (FFP) or, in current use, thawed plasma is the most readily available option but comes with risk of volume overload. We report our experience of using therapeutic plasma exchange (TPE) as an alternative perioperative management strategy. METHODS: A retrospective review of all HEM-C patients who underwent surgical procedures. Data were collected, including demographics, bleeding history, surgical site, perioperative hemostatic intervention, and outcome. RESULTS: Between July 1997 and September 2014, 28 HEM-C patients (12 men) were identified, 4 with severe disease (FXI:C <2% or excessive bleeding). Nineteen patients underwent 91 invasive procedures. For nearly 60% of the procedures, no periprocedural hemostatic intervention was provided; before 4 procedures (3 patients), 1 plasma volume TPE preoperatively with FFP was administered. Patient 1, a 28-year-old woman (FXI:C, 35%) with a history of excessive surgical bleeding, underwent 2 TPE procedures before laparoscopic pelvic biopsy and subsequent abdominal hysterectomy with salpingo-oophorectomy that increased her FXI:C to 48%. Patient 2, a 79-year-old man (FXI:C, <2%), had TPE before total hip arthroplasty, increasing his FXI:C to 24%. Patient 3, a 59-year-old man (FXI:C, <2%), had TPE before prostate laser enucleation, increasing his FXI:C to 46%. Patients 1 and 3 had mild reactions during TPE; no patient had evidence of volume overload. All patients had adequate intraoperative surgical hemostatic outcomes. CONCLUSION: TPE is an effective alternative presurgical hemostatic intervention in HEM-C with potentially lower risk of circulatory volume overload.

Clinical and laboratory characteristics in congenital ANKRD26 mutation-associated thrombocytopenia: A detailed phenotypic study of a family.

The clinical and laboratory characteristics of patients with non-syndromic, autosomal dominant thrombocytopenia secondary to germ line ANKRD26 mutations appear to be heterogeneous. Except for a targeted molecular genotyping approach, there is no distinct clinical or laboratory phenotype that has been specifically associated with this particular gene mutation. Such heterogeneity could be due to variations in mutation and genetic background in different families. To understand the phenotypic heterogeneity, we thoroughly studied one affected family using the International Society for Thrombosis and Haemostasis bleeding assessment tool and both clinically validated standard and esoteric platelet testing (electron microscopy (EM) and flow cytometry). We found that decreased platelet aggregation with arachidonic acid and epinephrine agonists was common in affected family members. EM studies demonstrated persistent borderline low mean dense granules per platelet, decreased alpha granules and an increased canalicular network pattern in all affected members. Since these characteristics are subtle or non-pathognomonic, molecular testing for ANKRD26 mutation remains the most reliable test to render a diagnosis and should be considered when evaluating a patient or family with congenital thrombocytopenia, particularly if there is a history of myeloid neoplasms.