Examination of the peripheral blood smear should be considered, along with review of the results of peripheral blood counts and red blood cell indices, an essential component of the initial evaluation of all patients with hematologic disorders. The examination of blood films stained with Wright's stain frequently provides important clues in the diagnosis of anemias and various disorders of leukocytes and platelets. Normal human red blood cells are biconcave disks (diskocytes) with a mean diameter of about 7.5 μm. Erythrocytes are slightly smaller than small lymphocytes. The hemoglobin of red cells is located peripherally, leaving an area of central pallor equal to approximately 30 to 45% of the diameter of the cells. Cells of normal size and hemoglobin content (color) are termed and Larger than normal erythrocytes are (diameter greater than 9 μm); small red cells are (diameter less than 6 μm); and those with central pallor greater than 50% of the diameter are Abnormal variability in size is termed unusual variation in shape is called and significant differences among erythrocytes in the amount of central pallor is referred to as means the erythrocytes have a blue-gray hue to the color of their cytoplasm. From a diagnostic standpoint, poikilocytosis has no specificity, but the recognition of specific forms of poikilocytes (irregularly shaped cells) often points to specific disorders. are round, densely staining red cells that lack central pallor and have a smaller than normal diameter. In , the area of central pallor is elliptical rather than round, giving the cell the appearance of the opening of a mouth (stoma). (codocytes) have a centrally located disk of hemoglobin surrounded by an area of pallor with an outer rim of hemoglobin adjacent to the cell membrane giving the cell the appearance of a target. (or wafer cells) are thin, flat cells with the hemoglobin at the periphery of the cell. (drepanocytes) are elongated, sometimes crescent-shaped, erythrocytes with pointed ends. (ovalocytes) range from slightly oval to elongated cigar-shaped forms. (dacryocytes) are red cells with one end round and the other end more pointed. have several (usually 3 to 7) irregularly spaced blunted projections from the margin of the cells. are also cells with cytoplasmic projections, but in contrast to acanthocytes, the projections are typically evenly spaced on the cell surface, more numerous (often 10 to 15), and frequently have sharper points. (schistocytes) are fragmented erythrocytes appearing in a variety of morphologic forms such as small triangular erythrocytes, helmet cells, and normal-size erythrocytes with 2 to 3 pointed surface projections (keratocytes, or "horn cells"). Round erythrocytes with a single, elliptical or round surface defect are termed is a phrase denoting the stacking of erythrocytes, generally in a curving pattern. Morphologic identification of inclusion bodies within erythrocytes can be helpful clinically. Howell–Jolly bodies are purple spheres, usually about 0.5 μm in diameter, presenting singly, or rarely multiply, in the cytoplasm. Basophilic stippling of erythrocytes refers to numerous very small coarse or fine blue granules within the cytoplasm. When the stippled particles are due to iron granules (demonstrable by the Prussian blue stain), they are termed Malaria parasites may appear as cytoplasmic inclusion bodies within erythrocytes. Platelets overlying erythrocytes may be mistaken for erythrocyte inclusions. There are a number of important morphologic abnormalities of mature granulocytes. Cytoplasmic vacuoles may be recognized. Toxic granulation refers to small, dark blue-staining granules. Döhle bodies are light blue cytoplasmic inclusions, 1 to 2 μm in diameter. The Pelger–Huët anomaly, a disorder characterized by impaired nuclear segmentation of mature neutrophilic granulocytes, appears morphologically as cells with bilobed nuclei (dumbbell or eyeglass shapes) or with round or oval nuclei (Stodtmeister cells). Hypersegmented neutrophils are cells in which there are six or more nuclear lobes. Reactive lymphocytes are usually larger than small lymphocytes, may have cytoplasmic vacuolization, sometimes have deep blue staining of the periphery of the cytoplasm, and contain nuclei that may be kidney bean or monocytoid in shape. Most platelets in the peripheral blood have diameters between 1 and 3 μm. Platelets greater than 3 μm in diameter are "large" (megathrombocytes). In a normal person usually less than 5% of the platelets appear large. Figure 155.1 shows examples of morphologically normal and abnormal erythrocytes.
外周血涂片检查，连同外周血细胞计数和红细胞指数结果的复查，应被视为所有血液系统疾病患者初始评估的重要组成部分。用瑞氏染色的血涂片检查常常能为贫血以及各种白细胞和血小板疾病的诊断提供重要线索。正常人体红细胞呈双凹圆盘状（盘状红细胞），平均直径约7.5μm。红细胞略小于小淋巴细胞。红细胞的血红蛋白位于周边，中央淡染区面积约占细胞直径的30%至45%。大小和血红蛋白含量（颜色）正常的细胞被称为 ；大于正常红细胞的是 （直径大于9μm）；小红细胞是 （直径小于6μm）；中央淡染区大于细胞直径50%的是 。大小的异常变异称为 ，形状的异常变异称为 ，红细胞中央淡染程度的显著差异称为 。 意味着红细胞胞质颜色呈蓝灰色。从诊断角度来看，异形红细胞症并无特异性，但识别特定形式的异形红细胞（形状不规则的细胞）往往指向特定疾病。 是圆形、染色致密的红细胞，无中央淡染区，直径小于正常。在 中，中央淡染区呈椭圆形而非圆形，使细胞看起来像嘴巴张开（气孔）。 （靶形红细胞）有一个位于中央的血红蛋白圆盘，周围是淡染区，细胞膜附近有一圈血红蛋白外缘，使细胞呈现靶形外观。 （或薄饼状细胞）是薄而扁平的细胞，血红蛋白位于细胞周边。 （镰状红细胞）是细长的、有时呈新月形的红细胞，两端尖锐。 （椭圆形红细胞）范围从略呈椭圆形到细长的雪茄形。 （泪滴形红细胞）是一端圆形另一端更尖的红细胞。 有几个（通常3至7个）从细胞边缘不规则间隔伸出的钝性突起。 也是有胞质突起的细胞，但与棘形红细胞不同，突起通常在细胞表面均匀分布，数量更多（通常10至15个）且常常有更尖锐的尖端。 （裂红细胞）是破碎的红细胞，呈现多种形态，如小三角形红细胞、盔形细胞以及带有2至3个尖锐表面突起的正常大小红细胞（角化细胞或“角形细胞”）。有单个椭圆形或圆形表面缺陷的圆形红细胞称为 。 是一个表示红细胞通常呈弯曲模式堆叠的术语。红细胞内包涵体的形态学识别在临床上可能有帮助。豪 - 乔小体是紫色球体，通常直径约0.5μm，单个或很少多个出现在细胞质中。红细胞嗜碱性点彩是指细胞质内众多非常小的粗或细蓝色颗粒。当点彩颗粒是由于铁颗粒（普鲁士蓝染色可显示）导致时，它们被称为 。疟原虫可能表现为红细胞内的细胞质包涵体。覆盖在红细胞上的血小板可能被误认为是红细胞包涵体。成熟粒细胞有许多重要的形态学异常。可识别细胞质空泡。毒性颗粒是指小的深蓝色染色颗粒。杜勒小体是淡蓝色细胞质包涵体，直径1至2μm。Pelger - Huët异常是一种以成熟嗜中性粒细胞核分叶受损为特征的疾病，形态上表现为双核叶（哑铃形或眼镜形）细胞或圆形或椭圆形核（施托德迈斯特细胞）。核分叶过多的中性粒细胞是指有六个或更多核叶的细胞。反应性淋巴细胞通常比小淋巴细胞大，可能有细胞质空泡化，有时细胞质周边有深蓝色染色，且含有可能呈蚕豆形或单核细胞样的核。外周血中大多数血小板直径在1至3μm之间。直径大于3μm的血小板是“大”血小板（巨大血小板）。在正常人中，通常不到5%的血小板看起来大。图155.1展示了形态正常和异常红细胞的示例。
