Gwen Clarke

Gwen Clarke
University of Alberta | UAlberta · Department of Laboratory Medicine and Pathology

BSc MD FRCPC

About

69
Publications
14,931
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1,492
Citations
Citations since 2017
24 Research Items
597 Citations
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
2017201820192020202120222023020406080100
Introduction
Gwen Clarke currently works at Canadian Blood Services and the Department of Laboratory Medicine and Pathology, University of Alberta. Gwen does research in Transfusion Medicine Hematology, and Pathology.

Publications

Publications (69)
Article
RÉSUMÉ Déclarations sommaires 1.Le génotypage RHD fœtal au moyen d’un test non invasif effectué sur l’ADN acellulaire a un degré d’exactitude élevé : il a une sensibilité constamment supérieure à 99 % et produit très peu de faux négatifs (II-2). 2.Même si le risque lié à l’exposition aux immunoglobulines anti-Rh est extrêmement faible, l’administ...
Article
Summary Statements 1.Non-invasive antenatal determination of fetal RHD genotype by cellfree DNA is highly accurate with sensitivities above 99% and very few false-negative results (II-2). 2.While the risks of Rh immune globulin exposure are exceptionally low, it is no longer considered appropriate to treat all D-negative pregnant women with human...
Article
Background: Preparing small-dose red cell concentrates (RCCs) is a common practice for pediatric and neonatal transfusions. However, there is a lack of quality monitoring data to indicate that both the preparation and storage of small-dose RCCs does not alter in vitro red cell quality. The present study seeks to provide data to support this practi...
Article
Full-text available
Background: Following delivery, blood tests are performed on umbilical cord blood (CB) to avoid neonatal venipuncture. Despite widespread and longstanding CB testing, no guidelines exist to suggest which immunohematology tests should be performed on CB. Study design and methods: We performed a scoping review, surveyed national practice, and deve...
Article
Background Irradiation of red blood cells (RBCs) inactivates residual donor T lymphocytes to prevent transfusion‐associated graft‐vs‐host disease (TA‐GVHD) but can have adverse effects on recipients and inventory management. Reported incidence of TA‐GVHD is lower when leukoreduced RBCs and older blood products are transfused; therefore, the impact...
Article
Objective: To provide family physicians with an understanding of blood bank tests performed during pregnancy. The value of routine blood type and antibody tests, as well as the follow-up required when a patient develops a red blood cell antibody or experiences a fetal-maternal hemorrhage (FMH) will be reviewed. Sources of information: The approa...
Article
Background and objectives The aims of the 19th International Society of Blood Transfusion Platelet Immunology Workshop were to compare the sensitivity and specificity of in‐house and commercially available methods for the detection of alloantibodies against human platelet antigens. Survey regarding laboratory management of samples collected for the...
Article
Background Intrauterine transfusion (IUT) is a treatment for fetal anemia. This technique involves ultrasound guided needle placement followed by transfusion of a specially prepared blood component. The most common indications include hemolytic disease of the fetus and newborn (HDFN) and prenatal infection. Methods The literature was reviewed, and...
Article
Objectives: This was a laboratory exercise designed to determine whether combined antibody titrations in the presence of multiple antibodies achieve a critical level earlier or at the same time as antibodies having individual antibody titrations. Background: Management of haemolytic disease of the fetus and newborn involves monitoring maternal a...
Article
BACKGROUND Many countries maintain rare blood programs to provide access to blood for patients with complex serologies. These include a process to screen donors and a registry to record information about rare donors; blood agencies may also freeze some units. However, frozen blood is much more expensive than liquid blood. STUDY DESIGN AND METHODS...
Article
BACKGROUND RhD DEL variants may show complete or partial expression of RhD epitopes. There have been only rare reports of anti‐D causing hemolytic disease of the fetus and newborn (HDFN) in this context. We report a case of severe HDFN associated with a recently described DEL variant. CASE REPORT A multiparous woman presented with an allo‐anti‐D a...
Article
Background: Intravenous unfractionated heparin infusion is often used to minimize the duration of time without anticoagulation around delivery in pregnant patients with high thrombotic risk. Activated partial thromboplastin time is commonly used to monitor and adjust heparin dose. However, using activated partial thromboplastin time is problematic...
Article
Background No direct and thorough accounting of costs related to packed red blood cells (PRBCs) has occurred in recent Canadian history. Our study sought to determine the cost accrued for a unit of PRBC within a Canadian hospital related to the inventory management, storage, testing, issuing and administration of the product. Methods An eight‐step...
Article
Conclusions: Rh is a complex blood group system with diverse genotypes that may encode weak and partial D variants. Standard serologic analysis may identify clinically significant D variants as D+; nevertheless, individuals with these D variants should be managed as D- patients to prevent antibody formation to absent D epitopes. Variant identifica...
Article
Actuellement, la meilleure façon de prendre en charge les femmes enceintes Rh négatives consiste à prédire la présence ou l'absence de l'antigène D chez le fœtus au moyen d'un test non invasif analysant l'ADN acellulaire (ADNa) dans le plasma maternel, et à administrer une prophylaxie à celles dont l'enfant est RHD positif. Cette approche, prise po...
Article
The optimal management of the D-negative pregnant woman is now based on the non-invasive antenatal prediction of fetal D-blood group by cell-free DNA (cfDNA) in maternal plasma, with targeted prophylaxis for women carrying RHD-positive fetuses. This provides the optimal care for D-negative pregnant women and has been adopted as the standard approac...
Poster
Two transfusion medicine (TM) physicians created eight TM cases and critical management items list for each case. Paper cards were designed to simulate blood bank products and laboratory values. TM physicians were trained to facilitate the simulation exercise with residents in small groups. The simulation provided residents with the opportunity to...
Article
Appropriate management of non-infectious adverse transfusion reactions begins with recognition that a change in clinical status during or following a transfusion may represent an adverse event. Appropriate monitoring of patients during transfusion and explicit training of staff to recognize the signs and symptoms of adverse transfusion reactions is...
Article
Background: RhIG prophylaxis for D- pregnant women prevents hemolytic disease of the newborn and typically depends on results of serologic D typing. Interpretation and follow-up of weak D serology is variable. Recent recommendations promote genotyping for RHD status determination in those with weak D serology. Canadian Blood Services performs comp...
Article
Background: HbA1c is used in the diagnosis and monitoring of diabetes mellitus (DM). Interference from hemoglobin variants is a well-described phenomenon, particularly with HPLC-based methods. While immunoassays may generate more reliable HbA1c results in the presence of some variants, these methods are susceptible to negative interference from hi...
Article
Despite the existence of long-standing, well-organized programs for Rh immune globulin (RhIG) prophylaxis, immune anti-D continues to be detected in the D– perinatal population. Between 2006 and 2008, 91 prenatal patients, found to have a previously unidentified anti-D, were followed up with a survey to their treating physician and with additional...
Conference Paper
Full-text available
Introduction: The Gerbich null (Ge-) or Leach phenotype is a rare blood group associated with RBCs that exhibit elliptocytosis. Our patient required a Ge-, O-red cell concentrate (RCC) for potential transfusion from a rare donor. During transportation from a collection site, the whole blood donation underwent a temperature deviation prior to manufa...
Article
Introduction: Most estimates of biologic variation (sb ) are based on periodically acquiring and storing specimens from reference subjects, followed by analysis within a tightly controlled analytic run. We demonstrate that reliable estimates of sb can be derived for virtually all constituents of the CBC from previously obtained paired patient resu...
Article
Objective: The goals of this study were to determine the prevalence and relative frequencies of red blood cell antibodies in a Canadian prenatal population, and to evaluate the fetal and neonatal outcomes of affected pregnancies. Methods: We conducted a retrospective review of pregnancies that screened positive for red cell antibodies between 20...
Article
Early neonatal central cyanosis that is unrelated to cardiopulmonary causes, alerts clinicians to possibility of methaemoglobinaemia. Congenital methaemoglobinaemia due to haemoglobin M is an autosomal dominant disorder characterised by lifelong cyanosis. We report a case presentation and review of diagnostic pitfalls of a newborn who presented wit...
Article
Background and Objectives Determining whether anti-D represents active or passive alloimmunization after RhIg administration is challenging. The objectives were to use antibody reaction strength to differentiate patients who may have become RhD alloimmunized during pregnancy from those manifesting passive anti-D and to investigate which methods wor...
Article
The hematology analyzers of today provide more reproducible analyses compared with those of a few decades ago, necessitating an evolution in hematology quality practices. The improved performance allows use of simple quality control rules. This improved performance also renders the repeat analysis of critical value specimens non value added. Some o...
Article
Full-text available
A 33-year-old woman of Indian origin presented for prenatal care at term. An ultrasound report from earlier in her pregnancy indicated complete placenta previa and placenta increta, which were confirmed by repeat ultrasound. She was admitted to the hospital for monitoring and delivery planning. On admission, brown vaginal spotting was noted on the...
Article
Objective Non-invasive fetal RhD genotyping using cell-free fetal DNA (cffDNA) in the maternal blood allows targeted antenatal RhD prophylaxis in unsensitised RhD negative women. The purpose of this study was to determine the cost and benefit of this approach compared with routine antenatal RhD prophylaxis for all unsensitised RhD negative pregnant...
Article
Body mass index (BMI), the prevalent indicator of obesity, is not easily grasped by patients nor physicians. Waist circumference (WC) is correlated to obesity, is better understood and has a stronger relationship to the metabolic syndrome. We compiled WC, complete blood count (CBC) parameters as well as other pertinent data of 6766 25 to 55 year ol...
Article
Background Transfusion-related acute lung injury (TRALI) is a severe transfusion reaction that manifests as acute respiratory compromise within 6 hours of the infusion of blood products. Intravenous immune globulin (IVIG) is prepared from large pools of human plasma and is commonly administered in the outpatient setting for the treatment of a wide...
Article
Full-text available
Fetal/neonatal alloimmune thrombocytopenia (FNAIT) can be a cause of severe fetal thrombocytopenia, with the common presentation being intracranial hemorrhage in the fetus, usually in the third trimester. A very unusual case of fetal anemia progressed to hydrops. This was further complicated by maternal Mirror syndrome and human chorionic gonadotro...
Article
Full-text available
Thrombotic thrombocytopenia purpura (TTP) is an infrequent but serious disease. Pregnancy is a known risk factor for presentation or relapse of TTP. Difficulties in differentiating TTP from preeclampsia/HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome, and current treatment recommendations are discussed in this case report. A wo...
Article
Full-text available
Posttransfusion purpura (PTP) is an uncommon, but potentially fatal, transfusion reaction characterized by profound thrombocytopenia and bleeding. PTP is caused by alloimmunization to human platelet specific antigens following blood component transfusion. Although there is evidence of a wide serological spectrum of culprit antibodies implicated, An...
Data
Use of the binomial theorem for automated clustering.
Article
Full-text available
Malaria is a serious infectious disease. According to the World Health Organization, it is responsible for nearly one million deaths each year. There are various techniques to diagnose malaria of which manual microscopy is considered to be the gold standard. However due to the number of steps required in manual assessment, this diagnostic method is...
Article
Healthy African Americans are known to have reduced white blood cell counts (WBC) and absolute neutrophil counts (ANC) compared with European Americans, with little agreement about the levels in reference intervals. The objective is to establish race-specific reference intervals for WBC and ANC using US National Health and Nutrition Examination Sur...
Article
Pediatric patients may require small-volume transfusions necessitating splitting of red cell (RBC) units. This process usually involves temporary storage of aliquots in pediatric blood bags or, in some cases, plastic syringes, until they are transfused. While many studies have been published on the efficacy of storage in blood bags, there is little...
Article
Transformation of polycythemia vera to chronic myelogenous leukemia is a rare event. We report 2 women with long-standing polycythemia vera who developed chronic myelogenous leukemia. Both patients had no BCR/ABL1 fusion at the time of polycythemia vera diagnosis but were positive for the fusion at chronic myelogenous leukemia onset. Most patients...
Article
Many remote hospitals keep small on-site stocks of red blood cell (RBC) units for emergency use and to support patient care programs. In Canada, the blood supplier does not accept returned units into inventory. Discard rates can, therefore, be high. To transport near-outdate RBC units to a high-usage hospital site, which would reduce overall discar...
Article
Context.—Many remote hospitals keep small on-site stocks of red blood cell (RBC) units for emergency use and to support patient care programs. In Canada, the blood supplier does not accept returned units into inventory. Discard rates can, therefore, be high. Objective.—To transport near-outdate RBC units to a high-usage hospital site, which would r...
Article
The purpose of this study was to validate a procedure for using red blood cell suspensions stored for up to 10 days in an immediate spin crossmatch. Ten group A and 10 group B SAG-M donor unit segments were opened on day 0. The red cells were divided into 2 tubes and each diluted with saline to a 3% to 5% cell suspension. The cell suspensions were...
Article
A high-performance liquid chromatography (HPLC) method designed for the measurement of haemoglobin (Hb)A(1c) in blood was investigated for use as a screening method for the presence of HbS in blood. In the Bio-Rad VARIANT II HbA(1c) method, HbS was found to have a specific retention time and percentage Hb value that enabled the detection of HbS in...
Article
Full-text available
Take-Home Message: The majority of transfusions occur in controlled conditions to surgical and chronically transfused patients. Emergent patients comprise a small proportion of transfusions. Rural hospitals do not proportionally transfuse more trauma patients than urban hospitals. Methods: All transfusions were categorized into either trauma, surgi...
Article
Febrile non-hemolytic transfusion reactions (FNHTRs) are a common complication of platelet concentrate (PC) and RBC transfusions, usually ascribed to cytokines released by WBCs and perhaps the platelets themselves during storage. Prestorage WBC reduction should abrogate the accumulation of these cytokines reducing the number of FNHTRs. A retrospect...
Article
Full-text available
Transfusion-related acute lung injury (TRALI) is a life-threatening complication of hemotherapy. We report a series of 90 TRALI reactions in 81 patients secondary to transfusion with whole blood platelets (72 reactions), apheresis platelets (2), packed red cells (15), and plasma (1). The overall prevalence was 1 in 1120 cellular components. To exam...

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