China
Africa
Explore chapters and articles related to this topic
Critical Care and Anaesthesia
Published in Tjun Tang, Elizabeth O'Riordan, Stewart Walsh, Cracking the Intercollegiate General Surgery FRCS Viva, 2020
Rajkumar Rajendram, Alex Joseph, John Davidson, Avinash Gobindram, Prit Anand Singh, Animesh JK Patel
What is a bleeding disorder and how do you screen for it?A congenital or acquired disorder that predisposes the patient to bleedingDiagnosed with the following blood tests: FBC and blood filmAPTT − intrinsic and common (X to fibrin) pathwaysPT − extrinsic (VII) and common pathways; expressed as INRTT − deficiencies of fibrinogen or thrombin inhibitionCoagulation factor tests − VIII, IX, etc.FDP levels − useful in DIC
Oedema, Haemorrhage and Thrombosis
Published in Jeremy R. Jass, Understanding Pathology, 2020
The term thrombosis describes the haemostatic process of platelet aggregation with concurrent formation of fibrin. It is also used to indicate the exaggerated process resulting in the formation of a pathological mass within the bloodstream. Physiological haemostasis and abnormal platelet aggregation differ quantitatively only. Platelets are small, non-nucleated, membrane-bound cytoplasmic fragments found within blood and formed by budding off from large multinucleated cells called megakaryocytes which are located within the bone marrow. They are of fundamental importance in the process of normal haemostasis. Endothelial injury leads to platelet adhesion (by the platelet adhesion molecule P-selectin) and aggregation, particularly upon exposure of the underlying basement membrane collagen. The adherent platelets attract more platelets by secreting ADP, thromboxane A2and serotonin. There is simultaneous activation of coagulation upon the platelet membrane which utilises fibrinogen released by the platelet. Additional factors serve to promote platelet aggregation, including thrombin and von Willebrand factor, the latter being released by damaged endothelial cells. Von Willebrand’s disease is a bleeding disorder resulting in deficiency of the factor and is inherited as an autosomal dominant trait. Platelet deficiency, affecting either numbers or function, is a further cause of bleeding disorders.
A Systematic Approach To The Diagnosis Of Bleeding Disorders
Published in Genesio Murano, Rodger L. Bick, Basic Concepts of Hemostasis and Thrombosis, 2019
The initial screening of a bleeding disorder includes: A blood smear and count for estimation of platelet numberA template bleeding time (TBT) and aspirin tolerance test (ATT) for evaluation of platelet and vascular integrityA prothrombin time (PT)A partial thromboplastin time (PTT)
Hemostasis-on-a-chip / incorporating the endothelium in microfluidic models of bleeding
Published in Platelets, 2023
Yumiko Sakurai, Elaissa T. Hardy, Wilbur A. Lam
Bleeding disorders (i.e. hemophilia and von Willebrand disease) affect hemostasis, and affected patients may exhibit various degrees of bleeding problems. Historically, patients with a suspected bleeding disorder underwent a “bleeding time test” to directly assess the patient’s bleeding risk. This test includes small incisions on the patient’s arm and recording the time when the bleeding stops [1] but the procedure is difficult to control and is invasive. Currently, the bleeding time test has largely been replaced by assays using blood collected through a venipuncture, assessing the risks of abnormal bleeding and blood clotting. Specifically, the assays include prothrombin and partial thromboplastin time, platelet function assays, and various viscoelastic tests. The assays can be performed as point-of-care in clinical settings [2–4] where timely assessment is needed in the emergency department, surgery, trauma involving hemorrhagic shock, and more recently, COVID-19-associated coagulopathy [5]. They can determine the patient’s hemostatic competence more precisely but other critical factors that control hemostasis in the body may be omitted. For example, the fluid dynamics of blood flow and blood interaction with the cells composing the vasculatures, i.e. endothelial cells and the underlying matrix. Additionally, the assays can determine the risk of the blood clotting through direct observation of platelet behaviors and coagulation, but bleeding risks are only indicated by the lack of or the reduced amount of activity. There is no direct observation of “bleeding” and hemostasis to assess patient’s hemostatic competence.
Gastrointestinal bleeding in von Willebrand patients: special diagnostic and management considerations
Published in Expert Review of Hematology, 2023
Edwin Ocran, Nicholas L.J. Chornenki, Mackenzie Bowman, Michelle Sholzberg, Paula James
Von Willebrand Disease (VWD) is the most prevalent-inherited bleeding disorder. The disease is autosomally inherited and is caused by a deficiency or dysfunction of von Willebrand Factor (VWF), resulting in impaired blood clotting. The trait may occur in about 1% of the general population, with a symptomatic prevalence of 1 in 1000 [1]. VWF plays essential roles in normal hemostasis including the protection of coagulation factor VIII (FVIII) from early degradation, the binding to exposed subendothelial collagen at sites of vascular injury, and the binding to platelet surface glycoproteins, which leads to platelet adhesion and subsequent platelet aggregation under high shear stress [2,3]. Recently, VWF has been linked to other non-hemostatic roles including inflammation, cell proliferation and angiogenesis, as discussed by Rauch et al. [3].
Testing strategies used in the diagnosis of rare inherited bleeding disorders
Published in Expert Review of Hematology, 2023
Patients with a high bleeding score but normal results of hemostatic testing may have collagen vascular bleeding disorder such as Ehlers-Danlos Syndrome (EDS). Major clinical manifestations of EDS variants include joint hypermobility, skin fragility, and hyperextensibility. The Beighton screening tool assesses for joint hypermobility (Table 3), seen in selected variants of EDS and assigns a score. This score provides a likelihood of joint hypermobility [12]; additional clinical findings in EDS variants with bruising as a prominent symptom are shown in Table 4. More detailed description of EDS variants is described in recent publications [13]. Although EDS variants were felt to be rare and are not included in the definition of RBD, a recent study estimated a prevalence of approximately 1 in 500 in the general population [14]. Follow-up testing for EDS, if indicated, consists of molecular genetic testing for genes implicated in each subtype of EDS listed in (Table 4). The modes of inheritance and genes implicated in the pathogenesis of each subtype vary. It should be noted that patients with EDS may also have co-existing hemostatic abnormalities [15]. Most of these variants have a relatively benign clinical course except for vascular type (formerly type IV), which has a propensity for life-threatening complications, such as arterial rupture. Finally, despite exhaustive testing, a defined group of patients with an evident bleeding tendency, but no diagnostic laboratory findings are categorized as bleeding disorders of unknown cause [16].