The sensitivity and specificity of the immediate-spin crossmatch

The immediate-spin (IS) crossmatch is used to detect ABO incompatibility between donor red cells (RBCs) and the serum of the intended recipient. However, this test may be positive in the absence of ABO incompatibility (false positive) or it may be negative when ABO incompatibility exists (false negative). During a 25-month study, the rates of both false-positive and false-negative IS crossmatch results were evaluated, and the sensitivity and specificity of the IS crossmatch were determined. During the study period, 53,656 IS crossmatches were performed for patients without significant RBC antibodies. Fifty-five patients had positive IS crossmatches, and no false-negative reactions were found. In tests of 55 patients with positive IS crossmatches, 77 false-positive and 5 true-positive reactions were noted. The causes of the false-positive reactions were rouleaux (36 patients), cold-reactive antibodies (8 patients), a combination of rouleaux and cold-reactive antibodies (2 patients), fibrin clot (1 patient), and undetermined (3 patients). The sensitivity and specificity of the IS crossmatch were 100 and 99.86 percent, respectively. Laboratory personnel should be aware that the IS crossmatch may have false-positive or false-negative results, and they should develop written protocols to distinguish quickly between true-positive and false-positive reactions.     

When should antibody screening tests be done for recently transfused patients?

The American Association of Blood Banks (AABB) requires that blood samples used for pretransfusion testing of recently transfused (or pregnant) patients must be obtained within 3 days of scheduled transfusions. This requirement, which became effective in July 1988, amended Standard G2.000 of the AABB, which previously required that pretransfusion testing must be done on blood samples obtained within 2 days of scheduled transfusions. The present study was designed to estimate the risk associated with adopting the amended version of Standard G2.000. Sixty patients who developed significant unexpected alloantibodies after transfusion were studied retrospectively. Thirteen of the 60 patients were found to have newly detectable antibodies within 83 hours of a sample reported to be negative for the new antibody. Had the amended version of Standard G2.000 been in effect, the detection of some of these antibodies might have been delayed up to 24 hours. It was estimated that the implementation of the new AABB requirement at the authors' institution could potentially place about 1 in 3000 transfused patients at risk for an acute or delayed hemolytic transfusion reaction.     

Survey on pretransfusion testing

BACKGROUND: Hospitals and blood centers throughout the United States use a variety of reagents and methods to perform pretransfusion testing. A survey was developed to determine the reagents and methods in use and their relative prevalence in different work settings. STUDY DESIGN AND METHODS: A national survey on pretransfusion testing was conducted. Surveys were distributed to state and regional blood bank associations, which then distributed them to hospitals and blood centers within their region. In most instances, the blood centers distributed the survey to the local hospitals. Completed surveys were returned to the authors for review, and all information was entered into a database for analysis. RESULTS: Analysis of the data shows that the majority of blood banks use monoclonal reagents for ABO testing and monoclonal-polyclonal blended reagents for Rh testing. The data show that anti-IgG and polyclonal antihuman globulin reagents are used almost equally for antibody screening (detection) tests and that most blood banks use a three-cell antibody-screening test. Slightly more than 50 percent of hospitals use an immediate-spin crossmatch in the absence of unexpected antibodies. CONCLUSION: A number of approved reagents and methods are used by blood bank laboratories for pretransfusion testing. Facility size (number of beds) and type tend to influence the choice of methods and reagents employed. This survey provides an opportunity for blood bank laboratories to compare their current practices with those of their peers.     

Effectiveness of a prospective physician self-audit transfusion- monitoring system

BACKGROUND: The purpose of this study was to search for a more effective transfusion-monitoring system than the existing system of retrospective peer review. STUDY DESIGN AND METHODS: This research used a study-control, preintervention and postintervention design, to evaluate the effectiveness of a prospective physician self-audit transfusion-monitoring system that functioned without the direct involvement of transfusion service physicians. This research also evaluated the effectiveness of issuing to physicians a memo with transfusion guidelines. Three process indicators were used to assess physician behavior at various stages of the blood-ordering process: 1) the number of crossmatches ordered per admission, 2) the transfusion-to- crossmatch ratio, and 3) the number of blood units returned to the laboratory after physician self-auditing. The study used two outcome indicators to reflect overall blood utilization: 1) the percentage of patients who received red cell transfusions and 2) the number of blood units transfused per recipient each month. RESULTS: The prospective physician self-audit system implemented at the study hospital did not reverse physician transfusion decisions, and the process of issuing to physicians a memo with transfusion guidelines at the control hospital failed to reduce blood usage. However, a transient reduction in blood utilization was observed at the study hospital. CONCLUSION: The reduction was hypothesized to be due to a Hawthorne effect, in which observed behavior is affected by the subject's awareness of the research study.     

The routine use of Rh-negative reagent red cells for the identification of anti-D and the detection of non-D red cell antibodies

BACKGROUND: Before 1987, fewer than 50 patients per year at the authors' laboratory had a positive antibody detection test due to antepartum Rhesus immunoprophylaxis. However, after 1987, a marked increase was observed in the number of patients who had received Rh immune globulin (RhIG) during pregnancy as part of routine antepartum Rh immunoprophylaxis. In anticipation that an increased use of RhIG during pregnancy would increase the number of patients in whom anti-D was detected by this laboratory, a protocol was developed to abbreviate the process required to identify anti-D. Although this protocol was adopted primarily to address an anticipated increase in antenatal RhIG usage in women, it was also applied to alloimmunized Rh-negative males. STUDY DESIGN AND METHODS: When an Rh-negative patient (male or female) had a reactive screening test for unexpected antibodies and met certain other criteria, the patient's serum was tested with a three-vial set of Rh-negative reagent red cells (Rh-negative screening RBCs), instead of with panels of typed RBCs (panel RBCs), for the identification of anti- D or the detection of non-D antibodies. If the serum under test did not agglutinate or hemolyze Rh-negative screening RBCs, anti-D was identified and no further testing was performed. If the serum agglutinated or hemolyzed Rh-negative screening RBCs, conventional testing with panel RBCs was done to determine the antibody specificity. RESULTS: Rh-negative patients (n = 1174) who had reactive screening tests for unexpected antibodies were tested with Rh-negative screening RBCs; 1079 were found to have anti-D as a single antibody. Seven of these patients subsequently developed a non-D alloantibody, after transfusion or pregnancy, and one patient had anti-C that escaped detection at the time of initial testing with Rh-negative RBCs (a false- negative result). Ninety-two patients had anti-D in combination with a non-D antibody, and three patients had a non-D antibody but not anti-D. Use of the anti-D identification protocol actually reduced the laboratory workload by 176 College of American Pathologists workload units per month, in spite of a marked increase in the number of patients in whom anti-D was detected. No hemolytic transfusion reaction was attributed to the abbreviation of anti-D identification. CONCLUSION: The identification of anti-D may be abbreviated without jeopardizing patient safety. Such a protocol can reduce laboratory workload and might be particularly appealing to health care facilities that perform antibody detection testing on large numbers of Rh-negative pregnant women, especially if antepartum RhIG is administered routinely.     

乌司他丁在预防不同胃肠术后吻合口瘘中的效果观察

目的探讨乌司他丁在预防不同胃肠术后吻合口瘘中的效果。方法选取2005年6月～2011年8月于本院进行胃肠术进行治疗的220例患者为研究对象,将其随机分为对照组和观察组各110例,观察组在对照组的基础上加用乌司他丁,后将两组患者中不同术式的吻合口瘘发生率及术前、术后1 d及3 d的血清超敏C反应蛋白（hs-CRP）、白介素2（IL-2）、白介素6（IL-6）、肿瘤坏死因子α（TNF-α）、血液流变学指标进行统计及比较。结果观察组不同术式的吻合口瘘发生率及总发生率均低于对照组,血清hs-CRP、IL-6、TNF-α水平低于对照组,IL-2高于对照组,血液流变学指标改变幅度小于对照组,差异均有统计学意义（均P〈0.05）。结论乌司他丁可以改善胃肠手术患者的炎性状态及血液循环情况,对于降低吻合口瘘的发生率有着积极的作用。     

Diagnostic Splenectomy for Visceral Leishmaniasis

A 57-year-old-man with a history of malaise, fever,night sweats and shortness of breath presented a diagnostic challenge to his medical team. He was pancytopaenic and had splenomegaly on admission but other investigations, including bone marrow aspiration, proved inconclusive. After the patient deteriorated clinically, the general surgical team was requested to perform a diagnostic splenectomy. The histology of this showed infection with visceral leishmaniasis. He recovered completely with Amphotericin treatment. Although this is a rare condition, particularly for the general surgeon, this case highlights the difficult position surgeons are often put in when performing major surgery diagnostically.     

多聚（ADP-核糖）聚合酶抑制剂对大鼠缺血再灌注肾脏损伤的保护作用

目的探讨多聚（ADP-核糖）聚合酶（PARP）抑制剂3-氨基苯甲酰胺（3-AB）在大鼠-肾脏缺血再灌注损伤中的保护作用及对肾组织血管内皮生长因子A（VEGF-A）和中性粒细胞明胶酶相关脂质运载蛋白（NGAL）mRNA表达的影响。方法将54只大鼠随机分为假手术组（S组）、再灌注后模型组（M组）和PARP抑制剂组（P组）,每组8只。比较各组大鼠右侧肾动脉缺血再灌注后2、6、12h后的血肌酐和尿素氮水平、肾脏组织病理学变化、肾组织PARP蛋白表达及肾组织VEGF-A和NGAI．mRNA表达。结果（1）M组各时间点的血肌酐、尿素氮水平均高于S组,P组各时间点血肌酐、尿素氮明显低于M组,差异均有统计学意义（P〈0．01）;（2）P组肾组织病理学表现较M组改善;（3）P组各时间点肾组织PARP表达明显低于M组,差异有统计学意义（P〈0．05）;（4）与M组相比,P组肾组织的VEGF-AmRNA的表达升高,NGALmRNA表达降低,有统计学差异（P〈0．05）。结论PARP抑制剂3AB对大鼠肾脏缺血再灌注损伤具有保护作用,可下调NGAL及上调VEGF-AmRNA表达。     

预防和治疗抗生素相关性腹泻的药学体会

目的:促进抗生素相关性腹泻的有效预防和治疗。方法:选用临床实例对以益生菌酸奶、活菌制剂及益生元等多种微生态制剂预防和治疗抗生素相关性腹泻的结果进行分析和总结。结果:实例表明,有抗生素相关性腹泻危险因素的患者给予益生菌酸奶和益生元后,能有效预防抗生素相关性腹泻的发生;已发生抗生素相关性腹泻的患者,应用微生态制剂后取得显著疗效。结论:合理应用微生态制剂能预防和治疗抗生素相关性腹泻。     

大连市乙肝疫苗查漏补种情况调查

[目的]了解大连市乙肝疫苗漏种的情况及其影响因素。[方法]2006年10月至2007年5月开展了大连市2002年7月1日至2006年9月3013出生儿童的乙肝疫苗查漏补种工作,对于在补种过程中新发现的漏种儿童,按照“随时发现,随时补种”的原则进行补种。[结果]本次“查漏补种”工作共摸底调查263727名儿童,查出漏种儿童2017人,漏种率为0．76％,应补种针次4198针次;实补种1933人,补种率为95．84％。大连市乙肝疫苗近5年平均接种率为99．9％,漏种率较低;流动儿童较本地常住儿童漏种率高（P〈0.05）,补种率低（P〈0．05）。[结论]流动儿童中仍存在免疫空白现象。