Tobler A
Hämatologisches Zentrallaborator der Universität, Inselspital Bern.
Schweiz Med Wochenschr. 1993 Apr 17;123(15):711-20.
Assessment of peripheral blood counts and blood film analysis are frequently performed as diagnostic procedures in emergency medicine. Far fewer situations exist, however, in which these analyses are the main clue in establishing an emergency diagnosis. Artifacts can lead to wrong diagnosis, e.g. pseudo-thrombocytopenia, which is defined as a low platelet count resulting from a laboratory artifact. Severe neutropenia (agranulocytosis) and extreme hyperleukocytosis, as well as suspicion of acute leukemia, require a rapid diagnostic work-up. A newly detected anemia should not necessarily be treated by packed red cell transfusions. The decision whether an anemic patient ought to receive transfusions should be based on the speed with which the anemia has developed, as well as on clinical judgement. As a rule a chronic anemia patient with hemoglobin above 70 g/l does not need transfusions. An uncritical transfusion policy can even cause emergencies, e.g. in patients with megaloblastic anemia or in anemic multiple myeloma patients with a hyperviscosity syndrome. An elevated hematocrit requires prompt further investigations. This is of utmost importance if one considers the diagnosis of polycythemia vera rubra, a disease in which patients are particularly prone to thrombotic complications. Fragmented red cells (schistocytes) on peripheral blood smears constitute a cardinal diagnostic clue for the detection of microangiopathic hemolytic anemias (MAHA), in particular for the diagnosis of the life-threatening thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Malaria is another example for a chief role of blood smears examination in achieving a rapid diagnosis. If one encounters an unexpected severe thrombocytopenia, a marrow examination reveals whether it is due to rapid peripheral destruction, or due to a marrow failure. Furthermore, in any patients with an unanticipated thrombocytopenia, a disseminated intravascular coagulation and a MAHA should be ruled out. Heparin-induced thrombocytopenia is a rare, but possibly fatal complication of therapy with heparins.
外周血细胞计数评估和血涂片分析在急诊医学中经常作为诊断程序进行。然而，这些分析作为确立急诊诊断的主要线索的情况要少得多。人为因素可导致错误诊断，例如假性血小板减少症，它被定义为由实验室人为因素导致的血小板计数偏低。严重中性粒细胞减少（粒细胞缺乏症）和极度白细胞增多症，以及怀疑急性白血病，都需要迅速进行诊断检查。新发现的贫血不一定需要输注浓缩红细胞进行治疗。贫血患者是否应该接受输血的决定应该基于贫血发展的速度以及临床判断。通常，血红蛋白高于70 g/l的慢性贫血患者不需要输血。不加批判的输血政策甚至可能引发紧急情况，例如在巨幼细胞贫血患者或患有高黏滞综合征的贫血多发性骨髓瘤患者中。血细胞比容升高需要立即进行进一步检查。如果考虑真性红细胞增多症的诊断，这一点至关重要，因为真性红细胞增多症患者特别容易发生血栓并发症。外周血涂片上的破碎红细胞（裂体细胞）是检测微血管病性溶血性贫血（MAHA）的主要诊断线索，特别是对于危及生命的血栓性血小板减少性紫癜（TTP）和溶血性尿毒症综合征（HUS）的诊断。疟疾是血涂片检查在快速诊断中起主要作用的另一个例子。如果遇到意外的严重血小板减少症，骨髓检查可揭示这是由于外周快速破坏还是骨髓衰竭所致。此外，对于任何意外出现血小板减少症的患者，都应排除弥散性血管内凝血和MAHA。肝素诱导的血小板减少症是肝素治疗罕见但可能致命的并发症。
