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Methodology of myelogram (red bone marrow examination)
Last reviewed: 04.07.2025

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To examine the red bone marrow, a puncture of the sternum or ilium is performed, and smears are prepared from the puncture for cytological analysis. When aspirating bone marrow, blood always gets in, the more blood the more aspirate is obtained. The puncture is usually diluted with peripheral blood by no more than 2.5 times. Signs of a greater degree of dilution of bone marrow with peripheral blood are as follows:
- Poverty of punctate in cellular elements.
- Absence of megakaryocytes.
- A sharp increase in the leukocyte-erythroblastic ratio (if the ratio is 20:1 or higher, the puncture is not examined).
- Decrease in the neutrophil maturation index to 0.4-0.2.
- Approaching the relative content of segmented neutrophils and/or lymphocytes to that in peripheral blood.
When examining red bone marrow, the percentage of bone marrow elements is calculated, and the absolute content of myelokaryocytes and megakaryocytes is determined.
- Myelokaryocytes. A decrease in the content of myelokaryocytes is observed in hypoplastic processes of various etiologies, exposure of the human body to ionizing radiation, some chemicals and drugs, etc. The number of nuclear elements decreases especially sharply in aplastic processes. With the development of myelofibrosis, myelosclerosis, the bone marrow puncture is scanty and the number of nuclear elements in it is also reduced. In the presence of a syncytial connection between the bone marrow elements (in particular, in myeloma), bone marrow puncture is difficult to obtain, therefore the content of nuclear elements in the puncture may not correspond to the true number of myelokaryocytes in the bone marrow. A high content of myelokaryocytes is observed in leukemia, vitamin B 12 -deficiency anemia, hemolytic and posthemorrhagic anemia, that is, in diseases accompanied by bone marrow hyperplasia.
- Megakaryocytes and megakaryoblasts are detected in small quantities, they are located along the periphery of the preparation, determination of their percentage in the myelogram does not reflect the true position, therefore they are not counted. Usually only an approximate, subjective assessment of the relative shift towards younger or mature forms is carried out. An increase in the number of megakaryocytes and megakaryoblasts can cause myeloproliferative processes and metastases of malignant neoplasms to the bone marrow (especially in gastric cancer). The content of megakaryocytes also increases in idiopathic autoimmune thrombocytopenia, radiation sickness during the recovery period, chronic myelogenous leukemia. A decrease in the number of megakaryocytes and megakaryoblasts (thrombocytopenia) can cause hypoplastic and aplastic processes, in particular, in radiation sickness, immune and autoimmune processes, metastases of malignant neoplasms (rare). The content of megakaryocytes also decreases in acute leukemia, B12 -deficiency anemia, myeloma, and systemic lupus erythematosus.
- Blast cells: an increase in their number with the appearance of polymorphic ugly forms against the background of cellular or hypercellular red bone marrow is characteristic of acute and chronic leukemia.
- Megaloblasts and megalocytes of different generations, large neutrophilic myelocytes, metamyelocytes, hypersegmented neutrophils are characteristic of vitamin B12 - deficiency and folate deficiency anemia.
- Myeloid elements: an increase in the number of their mature and immature forms (reactive bone marrow) is caused by intoxication, acute inflammation, purulent infections, shock, acute blood loss, tuberculosis, malignant neoplasms. Promyelocytic-myelocytic bone marrow with a decrease in the number of mature granulocytes against the background of a cellular or hypercellular reaction can cause myelotoxic and immune processes. A sharp decrease in the content of granulocytes against the background of a decrease in myelokaryocytes is characteristic of agranulocytosis.
- Bone marrow eosinophilia is possible with allergies, helminthic infestations, malignant neoplasms, acute and chronic myeloid leukemia, and infectious diseases.
- Monocytoid cells: an increase in their number is detected in acute and chronic monocytic leukemia, infectious mononucleosis, chronic infections, and malignant neoplasms.
- Atypical mononuclear cells: an increase in their number against the background of a decrease in mature myelokaryocytes can be caused by viral infections (infectious mononucleosis, adenovirus, influenza, viral hepatitis, rubella, measles, etc.).
- Lymphoid elements: an increase in their number, the appearance of naked forms (Gumprecht's shadow) with an increase in the cellularity of the red bone marrow can cause lymphoproliferative diseases (chronic lymphocytic leukemia, Waldenström's macroglobulinemia, lymphosarcomas).
- Plasma cells: an increase in their number with the appearance of polymorphism, binuclear cells, and a change in the color of the cytoplasm can cause plasmacytomas (plasmoblastomas, as well as reactive conditions).
- Erythrocytes: an increase in their number without disruption of maturation is observed in erythremia. An increase in the content of erythrocytes and a decrease in the leukoerythrocytic ratio can cause posthemorrhagic anemia and most hemolytic anemias. A decrease in the content of erythrocytes with a decrease in the total number of myelokaryocytes and a small (relative) increase in blast cells, lymphocytes, and plasma cells cause hypoaplastic processes.
- Cancer cells and their complexes are detected in metastases of malignant tumors.
To evaluate a myelogram, it is not so much the determination of the number of bone marrow elements and their percentage content that is important, but their mutual relationship. The composition of a myelogram should be judged by specially calculated bone marrow indices that characterize these relationships.
- The erythroblast maturation index characterizes the state of the erythroid germ and is the ratio of the percentage of normoblasts containing hemoglobin (i.e. polychromatophilic and oxyphilic) to the total percentage of all normoblasts. A decrease in this index reflects a delay in hemoglobinization, which is observed in iron deficiency and sometimes hypoplastic anemia.
- The neutrophil maturation index characterizes the state of the granulocytic germ. It is equal to the ratio of the percentage of young elements of the granular series (promyelocytes, myelocytes and metamyelocytes) to the percentage of mature granulocytes (band and segmented). An increase in this index in cell-rich red bone marrow indicates a delay in neutrophil maturation, while in cell-poor bone marrow it indicates an increased release of mature cells from the bone marrow and depletion of the granulocytic reserve. An increase in the neutrophil maturation index is observed in myeloleukemia, leukemoid reactions of the myeloid type, and some forms of agranulocytosis; its decrease is observed in delayed maturation at the stage of mature granulocytes or a delay in their washout (in hypersplenism, some infectious and purulent processes).
- The leukoerythroblastic ratio is the ratio of the sum of the percentage of all elements of the granulocytic lineage to the sum of the percentage of all elements of the erythroid lineage of the bone marrow. Normally, this ratio is 2: 1-4: 1, that is, in normal bone marrow the number of white cells is 2-4 times greater than the number of red cells. An increase in the index with high cellularity of the red bone marrow (more than 150×10 9 /l) indicates hyperplasia of the leukocyte lineage (chronic leukemia); with low cellularity (less than 80×10 9 /l) - about a reduction of the red lineage (aplastic anemia) or a large admixture of peripheral blood. A decrease in the index with high cellularity of the red bone marrow indicates hyperplasia of the red lineage (hemolytic anemia), with low cellularity - about a predominant reduction of the granulocytic lineage (agranulocytosis). The leukoerythroblastic ratio decreases in hemolytic, iron deficiency, posthemorrhagic, and B12 -deficiency anemias, increases in leukemias, and sometimes in the suppression of the erythroid germ in patients with hypoplastic anemia.