Judd W J, Fullen D R, Steiner E A, Davenport R D, Knafl P C
Blood Bank, Department of Pathology, University of Michigan Health System, Ann Arbor 48108, USA.
Transfusion. 1999 Mar;39(3):295-9. doi: 10.1046/j.1537-2995.1999.39399219287.x.
Omitting the 37 degrees C reading from screening tests for unexpected antibodies results in failure to detect some Rh, K, and Jk agglutinins of potential significance (wanted positives). However, this measure avoids unwanted positive tests due to cold agglutinins.
Using data from prior publications, actual risk calculations (ARCs) were made to predict the risk of eliminating the 37 degrees C reading, pretransfusion direct antiglobulin test (DAT), and routine indirect antiglobulin crossmatch (IAT-XM). ARCs used the equation: wanted positives missed x 0.34 (or 0.80) x 5 x percent antigen-positive, where 0.34 = percent of patients transfused (ARCs for 37 degrees C reading and DAT); 0.80 = percent of crossmatched patients transfused (ARCs for IAT-XM); 5 = average number of units transfused. Following elimination of the 37 degrees C reading, the impact of this change on patient care was monitored. Antibody detection and identification data and transfusion reaction reports for 6 months after the change were reviewed. Recently transfused patients with new antibodies were evaluated for immune hemolysis by review of clinical and laboratory data. The findings were compared with those from the same dates of the preceding year.
The risk of transfusing incompatible blood by eliminating the DAT, IAT-XM, and 37 degrees C reading is approximately 1:13,000, 1:2,000, and 1:2,400 units transfused, respectively. The cumulative risk from eliminating all three tests is approximately. 1 :1,000 units. With respect to the 37 degrees C reading, there were no differences between the pre-change and post-change study periods in the incidence of reported transfusion reactions or cases of immune hemolysis associated with newly formed antibodies. However, unwanted positive tests decreased from 162 to 61 following elimination of the 37 degrees C reading. This represents a decrease of 20 percent in the number of samples requiring antibody identification annually.
Eliminating the 37 degrees C reading from pretransfusion antibody screening tests imposes less risk than omitting the routine IAT-XM, and it avoids the time and costs of evaluating unwanted positive tests, thus reducing expenditures and delays in patient care.
在意外抗体筛查试验中省略37℃读数会导致无法检测到一些具有潜在重要意义的Rh、K和Jk凝集素（所需阳性结果）。然而，这一措施可避免因冷凝集素导致的不必要阳性试验。
利用先前出版物中的数据进行实际风险计算（ARC），以预测省略37℃读数、输血前直接抗球蛋白试验（DAT）和常规间接抗球蛋白交叉配血试验（IAT-XM）的风险。ARC使用的公式为：漏检的所需阳性结果数×0.34（或0.80）×5×抗原阳性百分比，其中0.34 = 输血患者百分比（37℃读数和DAT的ARC）；0.80 = 交叉配血患者输血百分比（IAT-XM的ARC）；5 = 平均输血量。省略37℃读数后，监测这一变化对患者护理的影响。回顾了变化后6个月的抗体检测与鉴定数据以及输血反应报告。通过回顾临床和实验室数据，对近期输血且产生新抗体的患者进行免疫溶血评估。将结果与上一年同期的结果进行比较。
省略DAT、IAT-XM和37℃读数而输注不相容血液的风险分别约为每输注13000、2000和2400单位血液出现1例。省略所有三项检测的累积风险约为每1000单位血液出现1例。关于37℃读数，在报告的输血反应发生率或与新形成抗体相关的免疫溶血病例方面，变化前和变化后的研究期间没有差异。然而，省略37℃读数后，不必要的阳性试验从162例降至61例。这意味着每年需要进行抗体鉴定的样本数量减少了20%。
在输血前抗体筛查试验中省略37℃读数所带来的风险低于省略常规IAT-XM，并且避免了评估不必要阳性试验的时间和成本，从而减少了支出并缩短了患者护理的延迟时间。
