QUESTION: I am suspicious that my patient with aortic stenosis may have acquired von Willebrand syndrome. What laboratory tests should I order if I suspect this diagnosis

Coberly, Emily

QUESTION: What is the difference between packed red blood cells that are called "CMV negative" and those that are called "CMV safe"

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5/30/2018 ASK A SPECIALIST: ASK A PATHOLOGISThttps://www.printfriendly.com/p/g/MWBn9U 1/2July 9, 2015ASK A SPECIALIST: ASK A PATHOLOGISTmedicine2.missouri.edu/jahm/ask-a-specialist-ask-a-pathologist/¹Emily Coberly MD¹Department of Pathology and Anatomical Sciences, University of Missouri Health Care, Columbia,MO and¹Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TNAddress correspondence to coberlyE@health.missouri.eduCitation: E Coberly, Ask A Specialist: Ask A Pathologist. Journal of Academic Hospital Medicine 2015Volume 7 Issue 3QUESTIONWhat is the difference between packed red blood cells that are called “CMV negative” and thosethat are called “CMV safe”?ANSWER Cytomegalovirus (CMV) infection may be transmitted through transfusion of cellular blood products(packed red blood cells and platelets).  There are currently two main methods available to reducetransfusion-transmitted CMV.  One option is to test individual blood donors for the presence of IgGand/or IgM antibodies against CMV at the time of donation, and to select blood products only fromdonors who test as negative (a “CMV negative” blood product).  The disadvantage to this method isthat it will not detect donors who are in the window period after acute CMV infection and have notyet had time to develop a detectable antibody response.The second strategy to reduce CMV transmission is to provide leukocyte reduced (“CMV safe”)blood products, in which the product is filtered to remove white blood cells.  Since CMV generallyresides within peripheral blood monocytes, filtering and removing white blood cells significantlyreduces the risk of transmission even from CMV positive donors.  The disadvantage of this methodis that a small number of residual white blood cells will remain after filtration, so transmission maystill occur if the donor has a high viral load at the time of donation.A large study comparing leukocyte reduced versus CMV negative transfusions in bone marrowtransplant recipients found no statistically significant difference in the rate of CMV transmissionbetween the two groups.   Subsequent smaller studies have shown mixed results, with leukocytereduction having either equivalent or slightly higher rates of CMV transmission compared to CMVnegative products.  The published failure rates for CMV negative or leukocyte reduced units rangebetween 1-4% for both methods.   However, many of these studies use an older, now obsolete filtertechnology for leukocyte reduction, so rates of CMV transmission may actually be much lower withcurrent filtration technology.15/30/2018 ASK A SPECIALIST: ASK A PATHOLOGISThttps://www.printfriendly.com/p/g/MWBn9U 2/2There are additional benefits to leukocyte reduction, including a decreased risk of febriletransfusion reactions and a decreased risk of HLA immunization.  Because of this, the majority ofblood collection centers in the US now perform universal leukocyte reduction on all cellular bloodproducts shortly after collection, and many hospitals are now providing only leukocyte reduced“CMV safe” blood products to all patients without needing a special order for this modification fromthe health care provider.  Check with your hospital’s blood bank to determine if they use universalleukocyte reduction for cellular blood products.References1. Bowden RA, Slichter SJ, Sayers M, et al. A comparison of filtered leukocyte-reduced andcytomegalovirus seronegative blood products for the prevention of transfusion-associatedCMV infection after marrow transplant. Blood. 1995 86: 3598-3603.Copyright © 2018 - The Curators of the University of Missouri System. All rights reserved. DMCA and other copyright information. An equal opportunity/affirmative actioninstitution.

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QUESTION: My patient has thrombocytopenia, but after the last platelet transfusion his platelet count only increased from 21,000/μL to 26,000/μL. Does he need crossmatched platelets

5/30/2018 ASK A PATHOLOGIST - American Journal of Hospital Medicinehttps://www.printfriendly.com/p/g/xgH9fp 1/2April 7, 2015ASK A PATHOLOGIST - American Journal of HospitalMedicinemedicine2.missouri.edu/jahm/ask-a-pathologist/¹Emily Coberly MD¹Department of Pathology and Anatomical Sciences, University of Missouri Health Care, Columbia,MO and ¹Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TNCorresponding Author: Emily Coberly coberlyE@health.missouri.eduCitation: E Coberly, Ask A Specialist: Ask A Pathologist. Journal of Academic Hospital Medicine 2015Volume 7 Issue 2QUESTIONMy patient has thrombocytopenia, but after the last platelet transfusion his platelet count onlyincreased from 21,000/µL to 26,000/µL. Does he need crossmatched platelets?ANSWERAs a general rule of thumb, transfusion of one unit of apheresis platelets or a single pooled unit (“5pack” or “6 pack”) of whole blood derived platelets is expected to increase an adult’s platelet countby about 30,000-50,000/µL. If two or more platelet transfusions result in a lower than expectedincrease in platelet count, platelet refractoriness should be considered. If platelet refractoriness is suspected, pre- and post-transfusion platelet counts should be measuredon at least two separate occasions. The post transfusion platelet count should be drawn 10 to 60minutes after the platelet transfusion is completed. These values can then be used to calculate thecorrected count increment (CCI):(Platelet count(post) – platelet count(pre)) x body surface area (m2) CCI = —————————————————————————————— Number of platelets transfused (x 1011)A total CCI of less than 5000 indicates platelet refractoriness.For the scenario in question, the change in platelet count of 5,000 multiplied by an average malebody surface area of 1.9 (m2) divided by the minimum required number of platelets in an apheresisunit of 3.0 (x 1011) equals 3167, consistent with platelet refractoriness. Units are usually omittedwhen reporting the CCI result.Platelet refractoriness may be caused by a variety of immune-mediated or nonimmune causes.Nonimmune mechanisms such as infection, fever, bleeding, DIC, splenomegaly and drugs accountfor the majority of cases of platelet refractoriness. In these cases, treatment should be aimed at the5/30/2018 ASK A PATHOLOGIST - American Journal of Hospital Medicinehttps://www.printfriendly.com/p/g/xgH9fp 2/2underlying cause whenever possible; crossmatched or HLA matched platelets are of no additionalbenefit over random platelets in non-immune cases.If nonimmune causes have been excluded, the next step is to confirm that the patient received ABOidentical or compatible platelet units. Although platelets do not require ABO matching, they doexpress a small number of ABO antigens which may contribute to a decreased count increment insome cases. If available, ABO compatible platelet units should be requested.When platelet refractoriness is immune-mediated, it is most commonly caused by antibodiesagainst HLA class I antigens or platelet specific antigens. In these cases, crossmatched platelets orHLA-matched platelets may be helpful. Crossmatched platelets can usually be obtained morequickly than HLA-matched platelets (1-2 days) and can detect HLA, ABO, and platelet specificantibodies. HLA-matched platelets generally take longer to obtain, but may be considered forpatients who are highly alloimmunized when crossmatch compatible platelets cannot be found. Ifimmune-mediated platelet refractoriness is suspected, consult your blood bank pathologist todetermine if crossmatched or HLA matched platelets may be an option for your patient.REFERENCESKopko PM, Warner P, Kresie L, Pancoska C. Methods for the selection of platelet products foralloimmune-refractory patients. Transfusion. 2015;55(2):235-244. Nester T, Jain S, Poisson J. Hemotherapy decisions and their outcomes. In: Fung MK, Grossman BJ,Hillyer CD, Westhoff CM editors. AABB technical manual. 18th ed. Bethesda, Maryland: AmericanAssociation of Blood Banks; 2014. 507-517.Copyright © 2018 - The Curators of the University of Missouri System. All rights reserved. DMCA and other copyright information. An equal opportunity/affirmative actioninstitution.

5/30/2018 ASK A SPECIALIST: ASK A PATHOLOGISThttps://www.printfriendly.com/p/g/s5Z4cP 1/2January 5, 2015ASK A SPECIALIST: ASK A PATHOLOGISTmedicine2.missouri.edu/jahm/ask-specialist-ask-pathologist-2/¹Emily Coberly MD¹Department of Pathology and Anatomical Sciences, University of Missouri Health Care, Columbia,MO and¹Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TNAddress correspondence to coberlyE@health.missouri.eduCitation:E Coberly, Ask A Specialist: Ask A Pathologist. Journal of Academic Hospital Medicine 2015Volume 7 Issue 1QUESTIONI am suspicious that my patient with aortic stenosis may have acquired von Willebrand syndrome. What laboratory tests should I order if I suspect this diagnosis?ANSWERThe association between aortic stenosis and bleeding, particularly mucosal bleeding fromgastrointestinal angiodysplasia, was described by Dr. Edward Heyde in 1958.  Since that time, it hasbeen determined that Heyde syndrome is associated with acquired type 2A von Willebrandsyndrome (AvWS), characterized by a loss of large von Willebrand factor (vWF) multimers.Although AvWS may also be seen in hematopoietic malignancies, hypothyroidism, and otherconditions, the mechanism of this acquired deficiency in cardiovascular disorders such as aorticstenosis or left ventricular assist device patients is thought to be high shear forces which inducestructural changes in vWF.  These changes expose the cleavage site for ADAMTS13 protease,leading to degredation and loss of high molecular weight vWF multimers.AvWS is common in patients with aortic stenosis and likely underdiagnosed; Vincentelli, et al, foundabnormal platelet function assays and a reduction in high molecular weight vWF multimers in 92%of patients with severe aortic stenosis and 50% of patients with moderate aortic stenosis.  Bleedingepisodes, most commonly from skin or mucosal sites, occurred in 21% of patients with severe aorticstenosis within the 6 months prior to valve replacement surgery.   Studies have found that AvWSdue to aortic stenosis improves with surgical valve replacement.Several laboratory tests are available to assist in the diagnosis of AvWS in patients with aorticstenosis:Platelet function assays (PFA-100) generally show prolonged closure times in AvWS, however thistest may also be abnormal in patients with platelet dysfunction from other causes and may befalsely prolonged in patients with significant anemia or thrombocytopenia.5/30/2018 ASK A SPECIALIST: ASK A PATHOLOGISThttps://www.printfriendly.com/p/g/s5Z4cP 2/2The ristocetin cofactor activity and vWF antigen levels may be normal or even elevated in AvWS dueto cardiovascular causes, as both are positive acute phase reactants.  The interpretation of ristocetincofactor activity and vWF antigen levels should include an assessment of ABO blood type, sincebaseline levels may be up to 30% lower in patients who are ABO blood type O.  A decrease in theratio of ristocetin cofactor to vWF antigen is consistent with the diagnosis of AvWS.vWF multimer analysis, which is often performed by Western blot, will show the characteristicdecrease in high molecular weight multimers.REFERENCESVincentelli A, Susen S, Tournea TL, et al.  Acquired von Willebrand Syndrome in Aortic Stenosis.  NEngl J Med 2003; 349:343-349.Tiede A, Rand JH, Budde U, et al.  How I treate the acquired von Willebrand syndrome.  Blood 2011;117:6777-6785.Copyright © 2018 - The Curators of the University of Missouri System. All rights reserved. DMCA and other copyright information. An equal opportunity/affirmative actioninstitution.

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