Abnormal Activated Partial Thromboplastin Time Research Articles

Coagulation Parameters as a Prognostic Factor for Mortality in a Neonate with Duodenal Obstruction

Background: Although the mortality cases of duodenal obstruction are only about 5%, this abnormality remains a burden in pediatric surgery. Several conditions can worsen a patient’s outcome and a proper understanding of the coagulation parameters is vital for a good outcome. Methods: This study was a descriptive-analytic study. Data of duodenal obstruction in neonate patients were taken from medical records from 2016 to 2020 . The data were then processed using SPSS 26.0 Results: From 59 samples of neonates with duodenal obstruction, most of them were born aterm pregnancy 38 (64%) patients, with male 32 patients and female 27 patients. There were neonates died based on complete obstruction 12 (20.3%), there was no significantly different neonates died between low birth weight and normal birth weight 9 (15.3%). The most commonly performed surgical procedure was kimura procedure 43 patients, with 14% patients was died. Coagulation parameters platelets, Protrombine time (PT), and Activated Partial Thromboplastin Time (APTT), only APTT there was significance correlation with P- value (0.016) , OR 3.98 Conclusion: There was a significant correlation between Activated Partial Thromboplastin Time (APTT) and mortality, with abnormal APTT had 3.98 times higher risk of dying than normal.

Analysis of APTT Based Clot Waveform Parameters in Various Clinical Conditions – A Study at A Tertiary Care Center

Various coagulation tests like Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) are estimated by automated coagulation analyzers. The newer fully automated analyzers generate clot wave forms aPTT-CWA for these parameters are derived. In this study, the objective was to analyze clot wave form characteristics morphology and its first and second derivative values in cases with abnormal APTT. ACL TOP 300 generated curves for APTT in a total 125 patients with 20 normal controls are included. First derivative, second derivative, morphology of curve: sigmoid, biphasic, prolonged pre-coagulation phase, second derivative morphology like early and late shoulder, biphasic peak, delayed deceleration were the analyzed parameters. Wave clot forms of 125 patients were included in this study. Patients (M:F - 2.2:1, mean age: 46.9 ± 20 years). A spectrum of clinical conditions was Covid (20%), liver disease (23%), polytrauma (10.4%), cardiac diseases (8.8%), sepsis/DIC (7.2%), thromboembolism (7.2%), renal diseases (6.4%), bacterial infections (4%), dengue (4%), snake bite (1.6%) and factor deficiency (1.6%). Liver and heart disease showed a significant difference in acceleration and deceleration peaks followed by sepsis, dengue, polytrauma and sepsis/DIC. Deceleration peak was prolonged in patients of Covid (p<0.05). Sepsis and liver diseases showed prolonged first derivative peak (p<0.05). CWA is very easily available on all automated coagulation analyzers. It is inexpensive with fast turn round time. Both quantitative as well as qualitative informations such as velocity, acceleration of clot formation and wave pattern details were recorded. Our study highlights importance of quantitative and qualitative CWA parameters acquired by performing APTT test for the automated analyzers.

Analysis of Risk Factors of Coagulation Dysfunction and Hemorrhage in Newly Diagnosed Hyperleukocytic Acute Myeloma Leukemia.

Purpose To explore whether and why abnormal coagulation function and hemorrhage can appear in patients with hyperleukocytic acute myeloid leukemia (HAML). Method We retrospectively reviewed the charts of 724 acute myeloid leukemia (AML) patients admitted with a white blood cell count of >100 × 109/L between 2010 and 2019 in order to analyze the coagulation index of patients with HAML and explore the correlation of abnormal coagulation. Result Prothrombin time (PT) was extended in group HAML compared with group non-HAML. Respiratory failure, intracranial hemorrhage, and infection were more common in the HAML group. Among the 76 HAML patients, there were 33 patients who had ≥3 abnormal items of coagulation index, and 51.5% of them had level 2 hemorrhage which was more than level 0 hemorrhage, and the difference is statistically significant (P < 0.01). Similarly, we can discover that 40.9% of patients with 2 abnormal items had level 2 hemorrhage in contrast to 0 abnormal items. The use of hydroxyurea had a significant effect on PT and D-dimer (DD). Survival analysis by the Kaplan–Meier method showed that there were statistically significant differences in white blood cell (WBC) count＞200 × 109//L and DD. Abnormal PT is associated with WBC count＞200 × 109//L, and abnormal activated partial thromboplastin time (APTT) is associated with HLA-DR mutation. Infection and respiratory failure were independent influencing factors for the coagulation of patients. Conclusion DD had a marked effect on the survival rate. Infection and respiratory failure were independent influencing factors for the coagulation of patients.

Relationship between admission coagulopathy and prognosis in children with traumatic brain injury: a retrospective study

BackgroundCoagulopathy in adult patients with traumatic brain injury (TBI) is strongly associated with unfavorable outcomes. However, few reports focus on pediatric TBI-associated coagulopathy.MethodsWe retrospectively identified children with Glasgow Coma Scale ≤ 13 in a tertiary pediatric hospital from April 2012 to December 2019 to evaluate the impact of admission coagulopathy on their prognosis. A classification and regression tree (CART) analysis using coagulation parameters was performed to stratify the death risk among patients. The importance of these parameters was examined by multivariate logistic regression analysis.ResultsA total of 281 children with moderate to severe TBI were enrolled. A receiver operating characteristic curve showed that activated partial thromboplastin time (APTT) and fibrinogen were effective predictors of in-hospital mortality. According to the CART analysis, APTT of 39.2 s was identified as the best discriminator, while 120 mg/dL fibrinogen was the second split in the subgroup of APTT ≤ 39.2 s. Patients were stratified into three groups, in which mortality was as follows: 4.5 % (APTT ≤ 39.2 s, fibrinogen > 120 mg/dL), 20.5 % (APTT ≤ 39.2 s and fibrinogen ≤ 120 mg/dL) and 60.8 % (APTT > 39.2 s). Furthermore, length-of-stay in the ICU and duration of mechanical ventilation were significantly prolonged in patients with deteriorated APTT or fibrinogen values. Multiple logistic regression analysis showed that APTT > 39.2 s and fibrinogen ≤ 120 mg/dL was independently associated with mortality in children with moderate to severe TBI.ConclusionsWe concluded that admission APTT > 39.2 s and fibrinogen ≤ 120 mg/dL were independently associated with mortality in children with moderate to severe TBI. Early identification and intervention of abnormal APTT and fibrinogen in pediatric TBI patients may be beneficial to their prognosis.

The effect of unfractionated heparin, enoxaparin, and danaparoid on lupus anticoagulant testing: Can activated carbon eliminate false‐positive results?

BackgroundHeparins and heparinoids interfere with functional clotting assays used for lupus anticoagulant (LAC) detection. However, current guidelines for LAC testing do not provide clear guidance on this matter. ObjectivesWe aimed to assess to effect of unfractionated heparin (UFH), enoxaparin, and danaparoid on LAC assays over broad anti‐Xa activity ranges and to evaluate whether activated carbon (AC) is able to neutralize these effects. MethodsUFH (0.1‐3.0 IU/mL), enoxaparin (0.2‐2.9 IU/mL), and danaparoid (0.6‐2.2 IU/mL) were spiked to normal pooled plasma. AC was added at multiple activity levels. Anti‐Xa assays and LAC tests were performed on all samples using Stago analyzers and reagents. ResultsAbnormal activated partial thromboplastin time (APTT) screening and mixing tests were obtained at the lowest levels for all compounds. Abnormal APTT confirmation tests were seen from 2.5 and 1.9 anti‐Xa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dilute Russell’s viper venom test (dRVVT) screening tests were obtained from 1.6, 1.4, and 1.1 anti‐Xa IU/mL for UFH, enoxaparin, and danaparoid, respectively. Mixing tests were abnormal from 2.5 and 1.3 anti‐Xa IU/mL for enoxaparin and danaparoid, respectively. Abnormal dRVVT confirmation results were seen for danaparoid only from 1.9 anti‐Xa IU/mL. AC was unable to neutralize anti‐Xa activity in plasma and overcome the effect of the tested anticoagulants on LAC assays but may cause prolongation of APTT clotting times. ConclusionsUFH, enoxaparin, and danaparoid clearly affected LA tests; however, false‐positive LAC conclusions were obtained at supratherapeutic enoxaparin and danaparoid levels only. AC may prolong APTT screen clotting times, requiring 3‐step testing to avoid potential misdiagnosis of LAC.

Determination of coagulopathy complicating severe preeclampsia and eclampsia with platelet count in a University Hospital, South-South, Nigeria

Background: Pre-eclampsia is a multisystemic disorder complicating pregnancy. It is associated with a significant burden on maternal and perinatal health, especially when complicated by coagulation abnormalities. Objective: The objective of the study was to determine the level of thrombocytopenia that predicts a risk of abnormalities of coagulation indices in severe preeclampsia and eclampsia. Materials and Methods: Haemostatic factors including platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT) and plasma fibrinogen were done for a cohort of 90 patients with severe preeclampsia and eclampsia at the Department of Obstetrics and Gynaecology, University of Benin Teaching Hospital, Benin City. Their demographic and laboratory data were analysed using the Statistical Package for Social Sciences version 20.0 and GraphPad InStat 3 software. Results: Twenty-one (23.3%) of the 90 patients had eclampsia. Mean age was 29.78 ± 4.7 years, parity was 2.54 ± 1.6 and gestational age was 36.14 ± 2.9 weeks. Thrombocytopenia was found in 13 (14.4%) patients, whereas biochemical coagulopathy was found in 6 (6.7%) patients. Thrombocytopenia was 43% more likely with eclampsia than severe preeclampsia (47.6% vs 4.3, P = 0.001). Abnormal PT, APTT and plasma fibrinogen were more likely with platelet count below 80000 cell/µl (P = 0.046, P = 0.014 and P = 0.001, respectively). Eclampsia complicated with thrombocytopenia was associated with the most severe biochemical coagulopathy. Conclusion: Thrombocytopenia frequently complicates eclampsia more than severe preeclampsia at platelet count levels below 80000 cell/µl. This level is discriminatory for biochemical coagulopathy, and it should prompt coagulation studies and warrant clinical vigilance.

The Platelet Function Analyser (PFA)-100 and von Willebrand disease: a story well over 16 years in the making.

The Platelet Function Analyser (PFA)-100 and von Willebrand disease: a story well over 16 years in the making.

Predictors of 1 year mortality in adult injured patients admitted to the trauma center.

Background:Traditional approach to predicting trauma-related mortality utilizes scores based on anatomical, physiological, or a combination of both types of criteria. However, several factors are reported in literature to predict mortality independent of severity scores. The objectives of the study were to identify predictors of 1 year mortality and determine their magnitude and significance of association in a resource constrained scenario.Materials and Methods:Prospective observational study enrolled 572 patients. Information regarding factors known to affect mortality was recorded. Other factors which may be important in resource constrained settings were also included. This included referral from a peripheral hospital, number of surgeries performed on the patient, and his socioeconomic status (below poverty line (BPL) card). Patients were followed till death or upto a period of 1year. Logistic regression, actuarial survival analysis, and Cox proportionate hazard model were used to identify predictors of 1year mortality. Limited estimate of external validity of the study was obtained using bootstrapping.Results:Age of patient, Injury Severity Score (ISS), abnormal activated partial thromboplastin time (APTT), Glasgow Coma Scale (GCS) score at admission, and systolic blood pressure (BP) at admission were found to significantly predict mortality on logistic regression and Cox proportionate hazard models. Abnormal respiratory rate at admission was found to significantly predict mortality in the logistic regression model, but no such association was seen in Cox proportionate hazard model. Bootstrapping of the logistic regression model and Cox proportionate hazard model provide us with a set of factors common to both the models. These were age, ISS, APTT, and GCS score at admission.Conclusion:Multivariate analysis (logistic and Cox proportionate hazard analysis) and subsequent bootstrapping provide us with a set of factors which may be considered as valid predictors universally. However, since bootstrapping only provides limited estimates of external validity, there is a need to test these factors against the well accepted requirements of external validity namely population, ecological, and temporal validity.

The Influence of Hemocoagulation Disorders on the Development of Posttraumatic Cerebral Infarction and Outcome in Patients with Moderate or Severe Head Trauma

Posttraumatic cerebral infarction (PTCI) is a severe secondary insult of head injury and often leads to a poor prognosis. Hemocoagulation disorder is recognized to have important effects on hemorrhagic or ischemic damages. We sought to assess if posttraumatic hemocoagulation disorders were associated with cerebral infarction, and evaluate their influence on outcome among patients with moderate or severe head trauma. In this study, PTCI was observed in 28 (10.57%) of the 265 patients within the first week after injury. In multivariate analysis, the thrombocytopenia (odds ratio (OR) 2.210, 95% confidence interval (CI) 1.065–4.674), abnormal prothrombin time (PT) (OR 3.241, 95% CI 1.090–7.648), D-dimer (>2 mg/L) (OR 7.260, 95% CI 1.822–28.076), or disseminated intravascular coagulation (DIC) scores (≥5) (OR 4.717, 95% CI 1.778–12.517) were each independently associated with an increased risk of PTCI. Admission Glasgow Coma Scale (GCS) score, abnormal activated partial thromboplastin time (APTT) and fibrinogen, and D-dimer (>2 mg/L) and DIC scores (≥5) showed an independent predictive effect on poor outcome. In conclusion, recognition of this important treatable cause of PTCI and the associated risk factors may help identify the group at risk and tailor management of patients with TBI.

Isolated Prolonged Prothrombin Time Correlates with Serum Immunoglobulin Levels in Patients with Multiple Myeloma

Abstract 1225▪▪This icon denotes a clinically relevant abstract Background:Secondary hemostatic defects resulting in bleeding diathesis occur in a subset of patients with plasma cell neoplasms due to a variety of mechanisms. Abnormal screening coagulation tests are frequently observed in asymptomatic patients with multiple myeloma and other plasma cell neoplasms. However, whether these coagulation abnormalities correlate with changes in serum proteins, diagnosis, or other disease parameters has not been systematically evaluated. Study Design:The objective of this study was to determine the prevalence of abnormal screening coagulation tests in patients with different plasma cell neoplasms and correlate clotting times with clinical history and diagnostic parameters. Methods:The medical records of 292 consecutive patients referred to the Myeloma Institute for Research and Therapy at UAMS from January 2010 to October 2010 were reviewed. Nineteen patients were excluded because they lacked screening coagulation tests or did not fulfill WHO diagnostic criteria for plasma cell neoplasm. Prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen activity were determined using mechanical detection. Abnormal APTT was defined as clotting times outside the normal range (23–36.9 sec). Prolonged PT was defined as ≥15.0 seconds (normal range: 11.5–14.7 sec) or INR > 1.2. Patients with prolonged PT or APTT due to warfarin therapy, liver disease or disseminated intravascular coagulation were also excluded. Results:A total of 79 patients had abnormal screening coagulation tests. An isolated prolonged PT was found in 62 patients (25%) and 10 patients had prolonged PT and APTT (3.5%). An isolated prolonged APTT was present in 2 patients (<1%) and decreased APTT seen in 5 patients (2%). According to the clinical notes, none of the patients had significant bleeding.Patients with isolated prolonged PT (62 total) and patients with normal screening tests (173 total) were compared with respect to age, fibrinogen, serum immunoglobulin level determined by protein electrophoresis, diagnosis, immunoglobulin isotype, and history of previous chemotherapy. There was no difference in age between patients with prolonged PT and those with normal PT (Table 1), previous chemotherapy or immunoglobulin isotype. Fibrinogen was significantly decreased in patients with prolonged PT (Table 1); however, there was no correlation between plasma fibrinogen and PT (p=0.1321). In contrast, serum immunoglobulin levels were significantly greater in patients with a prolonged PT (Table 1) and were positively correlated with PT (Figure 1).Table 1Patient CharacteristicsAll patients (mean ± SEM)PT < 15 sec (mean ± SEM)PT ≥ 15 sec (mean ± SEM)Age (yr)61.4 ± 0.71860.9 ± 0.83262.7 ± 1.415NSFibrinogen (mg/dL)414 ± 7.61427 ± 8.43377 ± 15.84p=0.0057Serum Immunoglobulin (g/dL)1.63 ± 0.1191.11 ± 0.0973.10 ± 0.287p<0.0001Values from patients with PT<15 sec were compared with those with PT≥15 sec using a Mann-Whitney (two-tailed) t-test. [Display omitted] As shown in Table 2, prolonged PT was more frequently observed in patients with multiple myeloma while patients with MGUS were less likely to have prolonged PT. No differences were observed with other plasma cell neoplasms; however, the numbers of patients in these diagnostic groups was small.Table 2:Patient DiagnosisDiagnosisAll PatientsPT <15 secPT ≥ 15 secORMultiple Myeloma (MM)157105523.37 (p=0.0009)MM, Non or Hyposecretory660NSMM with Plasmacytoma440NSSmoldering Myeloma21165NSMGUS343040.33 (p=0.037)Plasmacytoma11101NSAmyloid220NSTotal23517362Incidence of elevated PT in patients with indicated disease was determined by Fisher's exact test. Odds-Ratio (OR) was calculated using GraphPad Prism. Conclusion:An isolated prolonged PT (≥15 sec) was the most common abnormal coagulation test in our cohort. An association between disease severity and prolonged PT is suggested by our finding that patients with multiple myeloma were more likely to have prolonged PT than were patients with other plasma cell neoplasms. Of the factors examined, only serum immunoglobulin levels correlated with PT and were significantly elevated in patients with isolated prolonged PT. Disclosures:No relevant conflicts of interest to declare.

An assessment of the utility of unselected coagulation screening in general hospital practice

Coagulation screening using prothrombin time (PT) and activated partial thromboplastin time (APTT) is widely used. We performed an audit of coagulation screening in an Irish teaching hospital. We analysed PT and/or APTT results received during normal working hours during a 1-week period in our hospital. Abnormal results due to anticoagulants were excluded from further study. In samples with PT longer than 15.5 s and/or APTT longer than 42 s, we proceeded to 1: 1 mixing studies if the PT was prolonged and 1: 1 mixing studies, factor XII assay and lupus screen if the APTT was prolonged. We also obtained referral source for all samples and clinical details for abnormal samples. Six hundred and seventy-one coagulation requests were received during the study period. Three hundred and eighteen of 671 (47.4%) coagulation requests were for monitoring of anticoagulation. Three hundred and fifty-three of 671 (52.6%) requests were for coagulation screening rather than anticoagulant monitoring. In the coagulation screens received, PT was prolonged in 19 of 353 (5.4%). PT was longer than 20 s in four of 353 cases (1.1%). APTT was prolonged in 19 of 353 (5.4%). APTT was longer than 50 s in four of 353 (1.1%). No patients with abnormal PT or APTT had any bleeding sequelae during the study period. Unregulated coagulation screening has a low yield of abnormal results; the majority of these abnormal results show mild prolongation of PT or APTT with no evidence that they are associated with an increased bleeding risk.

A study of atypical APTT derivative curves on the ACL TOP coagulation analyser

The graphical representation of clotting data can provide useful information. A novel feature of the ACL TOP software allows display of clot reaction curves with superimposed first and second derivative curves. We noted atypical derivative plots associated with normal 'S'-shaped clot reaction curves in some abnormal activated partial thromboplastin time (APTT). We tested 179 citrate plasmas with four different APTT reagents on the ACL TOP. We documented the prevalence and utility of these APTT atypical derivative curves in these patients. Ellagic acid APTT reagents commonly produce atypical derivative curves despite normal 'S'-shaped clot reaction curves. Occasionally, these atypical second derivative curves may cause incorrect APTT results. With silica activator APTT reagents, atypical derivative curves were associated with genuine coagulation abnormalities such as single factor deficiencies and lupus anticoagulants (LAs). To our knowledge, this novel finding has not been reported. Atypical derivative curves seen in ellagic acid APTTs are of limited diagnostic use because of the frequency with which they occur. This may be related to the need to optimize the data reduction utilized on the ACL TOP for these reagents. With silica activator APTTs, the presence of atypical derivative curves proved to be a very simple tool when troubleshooting unexpected abnormal APTT results, commonly predicting a factor deficiency or LA that would warrant further investigation. The cause of these aberrant derivative curves is probably related to abnormal thrombin generation in the APTT test and warrants further study.

Clinical characteristics and outcomes of cerebral venous sinus thrombosis during pregnancy and puerperium

To explore the clinical features and outcomes of patients with cerebral venous sinus thrombosis (CVT) during pregnancy and puerperium. A retrospective study was performed in 24 cases of pregnant women with CVT among 15 625 deliveries in Xuanwu Hospital from January 2002 to October 2009, including 7 cases happened during pregnancy and 17 during puerperium. The etiology, clinical presentations, imaging examination results, other relevant examinations, and pregnant outcomes of these patients were analyzed. (1) Incidence and etiology: the incidence of CVT during pregnancy and puerperium was 0.15% (24/15 652) and 29% (7/24) of the patients fell ill during pregnancy and 71% (17/24) during puerperium. Five were complicated with severe preeclampsia, while another 5 complicated with hyperemesis. One woman was complicated with anemia. CVT was identified after spontaneous delivery in 9 cases and 8 after cesarean section. (2) CLINICAL PRESENTATIONS: Among the 24 CVT cases, 22 (92%) suffered from headache, 16 (67%) reported nausea and vomiting, 15(63%) experienced hyperspasmia and 6 (25%) complained of blurred vision. On admission, 8 (33%) patients were unconscious, 3 (13%) with hemiplegia, and 8 (33%) were febrile. (3) Imaging and laboratory examinations: twelve patients underwent digital subtraction arteriography (DSA) and were diagnosed. Fifteen women showed superior sagittal sinus thrombosis in MRI and magnetic resonance intravenous angiograph (MRV). Examination of the fundus found papilledema in 4 cases. Normal cerebral sinus fluid and laboratory routine tests were reported in 13 cases, but 6 cases of hyperlipidemia, 7 cases of abnormal activated partial thromboplastin time (APTT), 5 cases of abnormal international normalized ratio (INR), 3 cases elevated platelet count, 4 cases of positive D-dipolymer, 1 cases of low hemoglobulin level (<10 g/L), 4 cases with abnormal hematocrit, and 10 cases of elevated fibrinogen (>4 g/L) were identified. (4) Management and pregnancy outcomes: among the 7 cases happened during pregnancy, 2 were complicated with severe preeclampsia and delivered through cesarean section immediately and discharged after proper management including depressurization, spasmolysis, dehydration and anticoagulant therapy. Five of the 7 cases presented with CVT during early pregnancy, among which 1 was discharged after dilation and curettage followed by anticoagulant therapy, 2 received endovascular thrombolysis after which one was discharged and the other one left with right hemiparesis and 2 patients died. Among the 17 patients presented with CVT during puerperium, 10 received anticoagulant therapy after which 4 were fully recovered, 5 left with functional disturbance (3 with hemiplegia, 1 with incomplete motor aphasia and hemiparesis and 1 with blurred vision) and one died. Among the rest 7 cases who underwent endovascular thrombolysis, 3 were fully recovered, 3 left with functional impairment (1 with blind and headache and 2 with hemiplegia), and one died. Altogether, there were 14 patients underwent systemic anticoagulant therapy after which 7 were fully recovered, 5 left with dysfunction and 2 died. Among the 10 cases received endovascular thrombolysis, 4 were fully recovered, 4 remained some dysfunction and 2 died. CVT, mostly presented as superior sagittal sinus thrombosis, are more common in puerperium than during pregnancy and DSA is the golden standard for the diagnosis of CVT. Anticoagulant therapy and endovascular thrombolysis are effective in the treatment of CVT, but may left the patients with functional disturbance or even death. Prompt diagnosis and treatment ensure a better outcome for pregnant women complicated with CVT.

Inadvertent postdialysis anticoagulation due to heparin line locks

Large-bore dual lumen in-dwelling venous catheters are used in hemodialysis. These catheters are usually locked with heparin after the treatment. This study addressed the underappreciated postdialysis coagulopathy that can result. Thirty-six patients were included: 7 dialyzed through arterio-venous fistulae, 29 through in-dwelling venous catheters. The latter group was further subdivided according to whether they received heparin or heparin-free dialysis. To assess the heparin lock, a full-dose heparin lock as well as a much weaker heparin lock and a citrate lock were used. To assess the coagulopathy, blood was taken 1 hr after dialysis. The activated partial thromboplastin time (APTT) and anti-Xa level was measured. Additionally, 6 venous catheters were removed and the amount of fluid expelled upon locking with saline was measured. Clotting from the patient group with arterio-venous fistulae was normal following dialysis. The patients with in-dwelling venous catheters and heparin locks had significantly deranged clotting; 6 out of 10 patients had abnormal APTT results. All patients with catheters, heparin-free dialysis, and heparin locks had deranged clotting (7 out of 7). The rate decreased significantly when heparinized saline was used as a lock. A subset of patients had a citrate lock rather than a heparin lock; the clotting results normalized in all but one patient. An in vitro study demonstrated immediate leakage of fluid from the end of the ports upon locking. Significant postdialysis anticoagulation can occur after dialysis, which can be attributed to the heparin line locks. This risk is considerably reduced when a citrate lock is used instead.

Disseminated Intravascular Coagulation in Cattle with Abomasal Displacement

The purpose of the study was to evaluate haemostatic function in cattle with abomasal displacement (AD) and to reflect the occurrence of disseminated intravascular coagulation (DIC). Ten adult cattle with left displacement of abomasum (LDA) (group I), 10 adult cattle with right displacement of abomasum with volvulus (RDA) (group II) and 10 clinically healthy adult cattle (control group) were used as material. Numbers of platelets (PLT) and coagulation tests (activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), serum fibrin/fibrinogen degradation products (FDPs), fibrinogen) were measured before the surgical treatment of cattle with LDA and RDA. APTT was prolonged only in group II compared with the control and group I (p<0.05). However, when the individual values of coagulation profiles of each cow were evaluated, two cattle in group I and three cattle in group II had at least three abnormal coagulation profiles, which reflect the occurrence of DIC. These cattle died after surgical treatment. The two cattle with LDA had abnormal APTT, FDPs and PLT values; three cattle with RDA had abnormal APTT, PT, TT, FDPs and PLT values. APTT (5 cases), FDPs (5 cases) and thrombocytopenia (5 cases) were the three most common abnormal tests on coagulation profile in the cattle with LDA and RDA. The results of the study indicate that cattle with AD had a spectrum of haemostatic dysfunction and that DIC was a significant risk factor for mortality.

The multiple faces of the partial thromboplastin time APTT

The multiple faces of the partial thromboplastin time APTT

Auto-anticorps anti-facteur VIII et infection à Chlamydia pneumoniae

We report the case of a 64-year-old man without haemorragic history experiencing epistaxis. The standard haemostasis assessment including prothrombin index, activated partial thromboplastin time (APTT) and platelet count found an isolated abnormal APTT (105 sec vs 33 sec). Therefore, coagulation factors were explored. An acquired factor VIII deficiency (5%) with anti-FVIII antibody (4.5 Bethesda unit·mL –1) was recognised. This anti-FVIII antibody was related to a Chlamydia pneumoniae pulmonary infection. Treatment consisted of : i) Four successive anterior packing and activated factor VII infusion (Novoseven®) ; ii) steroids injection and bi-antibiotherapy. The time course of the epistaxis was favourable under treatment.

Differential effects of unfractionated heparin and low-molecular-weight heparins on tissue thromboplastin inhibition test.

Circulating anticoagulants are endogenously produced substances that interfere with in vitro tests of coagulation like activated partial thromboplastin time (APTT), and cause prolongation of the clotting times. Evaluation of the abnormal APTT involving various factor assays and mixing studies may provide inconclusive and ambiguous results. Tissue thromboplastin inhibition test (TTIT) is one of the screening assays for detection of circulating anticoagulants. However, this test is influenced by the presence of unfractionated heparin (UFH) from concentrations 0.2 U/mL and higher. Since low-molecular-weight heparins (LMWHs) are increasingly used for the prevention of thrombotic disorders and may replace UFH in the future, in this study the authors studied the influence of LMWHs on the performance of TTIT and compared the results with UFH. UFH and LMWHs showed a prolongation of TTIT in the concentration range of 0.25-1.0 U/mL. The marked prolongation of the TTIT with UFH and different LMWHs is in decreasing order of UFH > ardeparin > tinzaparin > dalteparin > enoxaparin. Patients with circulating anticoagulants who are given LMWHs may have false-positive results of TTIT and this influence should be kept in mind during patient management.

Laboratory performance of haemophilia centres in developing countries: 3 years' experience of the World Federation of Hemophilia External Quality Assessment Scheme.

A World Federation of Hemophilia External Quality Assessment Scheme has been established to promote high standards of laboratory performance in haemophilia centres worldwide. Results from 21 International Haemophilia Training Centres (IHTCs) provide target values for the prothrombin time (PT), activated partial thromboplastin time (APTT), factor VIII:C, IX:C and von Willebrand factor (VWF) assays, against which the performance of Haemophilia Centres in developing countries (HCs) can be assessed. Eight surveys were distributed over a 3-year period between 1994 and 1997. A higher proportion of HCs failed to identify an abnormal PT or APTT in samples from donors with mild deficiencies of the extrinsic and intrinsic systems, respectively. For factor VIII:C and IX:C assays, agreement between HC results was consistently poorer than between IHTCs. However, improvement in between-centre agreement could be seen for two samples distributed on more than one occasion. A minority of HCs perform assays for VWF, and a questionnaire revealed equipment and reagent costs as limiting the range of assays which could be carried out in several centres. However, agreement was in some cases better between those HCs that did perform VWF assays than between IHTCs. The problems of screening test sensitivity and between-centre agreement for factor assays need to be addressed, together with the limitations which prevent HCs from performing a full range of tests in the diagnosis and treatment of bleeding disorders.

Lupus anticoagulant in patients with peripheral vascular disease: A prospective study

To assess the incidence of lupus anticoagulant (LAC) in patients with peripheral vascular disease. Prospective clinical study. University Hospital. 20 patients with claudication (group 2), 20 patients with critical ischaemia (group 3) and 20 patients prior to elective abdominal aortic aneurysm surgery (group 4) were compared to 20 general surgical controls (group 1). Venous blood samples for coagulation assay. Positive results for LAC by the Dilute Russell's viper venom time (DRVVT) with the platelet neutralisation procedure were present in 26 out of 60 vascular patients compared with none of the 20 general surgical controls. The three vascular groups showed a similar prevalence of LAC and this differed significantly from that in the control group (chi 2 = 10.94, p = 0.0009). Of the 26 positive results only three were associated with an abnormal activated partial thromboplastin time (APTT), which has previously been used as a marker for the presence of LAC activity. Fibrinogen levels were raised in seven of 20 patients in group 2 but were normal in the remaining vascular groups (p = 0.001). The mean factor VII level (124.1 units dl-1) in group 2 was higher than the mean of the remaining vascular patients (109.3 units dl-1, p < 0.05). The high prevalence of LAC in patients with peripheral vascular disease and the associated increased risk of early graft thrombosis may justify routine testing by DRVVT prior to reconstructive vascular surgery. Treatment of these patients with antiplatelet agents or formal anticoagulation perioperatively should be considered.