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Mucocutaneous bleeding symptoms and/or persistent thrombocytopenia occur in individuals with congenital disorders of platelet function and number. Apart from bleeding, these disorders are often associated with additional hematologic and clinical manifestations, including auditory, immunologic, and oncologic disease. Autosomal recessive, dominant, and X-linked inheritance patterns have been demonstrated. Precise delineation of the molecular cause of the platelet disorder can aid the pediatrician in the detection and prevention of specific disorder-associated manifestations and guide appropriate treatment and anticipatory care for the patient and family., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Inherited platelet function disorders are of variable severity and unknown frequency and may be difficult to diagnose. Nevertheless, they are increasingly recognized as an important cause of bleeding in pediatrics, particularly in adolescent girls with menorrhagia, where they may be more common than von Willebrand disease. This article reviews the presentation of these disorders, summarizes the most common types of platelet function disorders, discusses the challenges in diagnostic testing, and details treatment and supportive care options., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to assess perioperative platelet function with 2 types of monitors (a whole-blood aggregometer [WBA analyzer; Mebanix, Tokyo, Japan]) and the Sonoclot monitor [Sienco, Wheat Ridge, CO]) in patients undergoing hypothermic cardiopulmonary bypass (CPB)., Design: Prospective, observational study., Setting: Single-center study at a university hospital., Participants: Twenty-six patients who underwent coronary artery bypass grafting or valve replacement under hypothermic CPB without platelet transfusion or fresh frozen plasma administration., Interventions: Blood sampling was performed at the following time periods: after anesthetic induction, after CPB, and on the first postoperative day. These samples were assessed with the WBA analyzer and the Sonoclot., Measurements and Main Results: Significant attenuation of adenosine diphosphate-induced platelet aggregation was detected shortly after CPB by 2 WBA analyzer-derived parameters: a decrease in the filtration pressure rate and an increase in the platelet aggregatory threshold index. Platelet aggregation returned to the preoperative level on the next day. There was no correlation between the amount of postoperative mediastinal drainage and defects in platelet aggregation. On the other hand, time to peak obtained by the Sonoclot did not show any significant changes., Conclusions: Whole-blood aggregation measured with the WBA analyzer detected transient platelet dysfunction shortly after CPB, whereas the Sonoclot was less sensitive to this change.

Amyloid diseases can be associated with potentially life-threatening hemorrhage. Pathogenetic factors contributing to the abnormal bleeding tendency in this setting are heterogeneous and depend on the type of amyloidosis and pattern of organ involvement. In patients with light-chain (AL) amyloidosis, acquired hemostatic abnormalities, including coagulation factor deficiencies, hyperfibrinolysis, and platelet dysfunction, can be regarded as the most important pathogenetic factors. In patients with other types of amyloidosis, acquired hemostatic defects are rare, and amyloid deposition has also been reported to be the main cause of abnormal bleeding manifestations. Amyloid angiopathy with increased fragility of blood vessels and impaired vasoconstriction may promote bleeding in this setting. Rupture of solid organs caused by amyloid deposition also was reported. Whereas therapeutic options in bleeding caused by local amyloid deposition are restricted to supportive measures and, in severe cases, surgery, acquired hemostatic defects may be treated according to the causative mechanism. In this review, we focus on bleeding risks in patients with amyloid diseases. Current concepts with regard to pathophysiology, diagnosis, and treatment are summarized and discussed.

Platelets are small, disc-shaped, anucleated cells formed by fragmentation of megakaryocytes in the bone marrow. They circulate in blood with a lifespan of 7 to 10 days and, together with fibrin, form hemostatic plugs at sites of vessel injury. Abnormalities of platelets, either quantitative or qualitative, may cause clinically significant bleeding with resultant morbidity and, on occasion, mortality. This review will focus on platelet disorders in neonates, defined as infants of up to 4 months of age. Special emphasis will be given to the physiology of platelet function in healthy and sick newborn infants. The review will be divided into sections as follows: role of platelets in hemostasis, platelet function in newborn infants, quantitative platelet disorders, qualitative platelet disorders, and platelet transfusion therapy.