Contents
Bone marrow (BM) is the most important hematopoietic (myeloid) tissue of the human body. Stem cells multiply and mature in it – the precursor cells of all blood cells: erythrocytes, leukocytes, platelets. They are the main component of the bone marrow. Bone marrow is inside all the bones of the human body. Bones have a porous structure, densely penetrated by permeable vessels, into which young blood cells easily enter.
There are two types of CM: red and yellow. The mass of the KM is about 4,6% of the total weight of a person. At the same time, the weight of its red and yellow types in the bones is approximately the same. Red bone marrow is located in the pelvic bones, flat bones, ends of tubular bones and vertebrae. It is in it that the processes of hematopoiesis take place.
The yellow type is localized in the cavities of the tubular bones and represents adipose tissue, which serves as a reserve for the red type of CM. Under conditions of an acute shortage of young blood cells, the yellow brain transforms into red and hematopoiesis begins in it.
A myelogram is the result of an intravital qualitative and quantitative study of the tissue and cellular composition of the bone marrow. The term comes from words of Greek origin and literally translates as “bone marrow record”. The interpretation of the results of the study of a smear or punctate of the KM is drawn up in the form of a table, which presents the percentage of different cells.
Unlike blood, which can be easily sampled from peripheral vessels for analysis, CM is not available for simple sampling. To perform its study, it is necessary to perform a puncture or biopsy of the bone. This manipulation for a hematologist is not difficult, but requires special tools and appropriate qualifications of the doctor, so it is not performed in conventional clinical laboratories.
Taking biomaterial
A red CM is required for myelogram. A sample can be obtained by puncture of the sternum (sternal puncture), biopsy of the ilium (trephine biopsy), calcaneus, femur, or tibia.
The first two procedures for taking a biomaterial sample in hematology are used most often. Trepanobiopsy allows you to get a large amount of biomaterial for research. BM sampling from the calcaneus and other leg bones is used in newborns and young children.
Indications and contraindications
The purpose of the study of BM is to identify violations of hematopoiesis. Myelogram study is indicated for:
- anemia (except for iron deficiency) and cytopenias;
- causeless increase in ESR in the general blood test;
- acute and chronic leukemias;
- erythremia;
- myeloma;
- lymphogranulomatosis and non-Hodgkin’s lymphomas;
- metastasis of malignant tumors in the bone;
- hereditary diseases (diseases of Nimmann-Pick, Gaucher, Urbach-Wite);
- splenomegaly of unknown origin.
Bone marrow puncture is performed to establish the stage and phase of leukemia, their differential diagnosis with leukemoid reactions. Myelogram examination is indicated to determine the histocompatibility of the bone marrow of the donor and recipient.
Sternal puncture or trepanobiopsy is contraindicated in patients with acute myocardial infarction, stroke, at the time of an attack of angina pectoris, suffocation, with a hypertensive crisis.
Preparing for the procedure
The procedure for taking CM is common in hematology. No special preparation of the patient for sternal puncture or trepanobiopsy is required.
Preparation for manipulation differs little from preparation for other minimally invasive procedures:
- the patient should be examined before the manipulation (general blood test, coagulogram);
- in a few days, anticoagulants and antiplatelet agents are canceled, as well as all other medicines, except for vital ones;
- for several hours the patient should not eat and drink (if the procedure is scheduled for the afternoon, the patient needs a light breakfast in the morning);
- 2 hours before the manipulation, you need to empty the intestines, and immediately before it – the bladder;
- if there is hair at the site of the future skin puncture, they are shaved off.
If the subject has any allergies, the doctor should be notified, especially if it is an allergic reaction to local anesthetics.
On the day of biomaterial sampling, the patient should not be prescribed other procedures and surgical interventions. With a strong sense of fear, the patient should take sedatives half an hour before the procedure, which should be reported to the doctor. Sternal puncture and trepanobiopsy are not pleasant manipulations, but it is difficult to attribute them to painful ones.
The puncture site of the skin and periosteum is treated with a local anesthetic, so pain in this place is not felt.
Immediately before the procedure, the patient is given informed consent to the manipulation: the course of its implementation is explained to him, as well as possible complications after it. If the puncture is for minor children, informed consent is taken from their parents or other legal representatives.
Carrying out a bone marrow puncture
The patient is placed on the couch: during sternal puncture – on the back (a roller is placed between the shoulder blades), with trepanobiopsy – on the right side or abdomen. The puncture site is treated with an alcoholic solution of iodine and anesthetized with local anesthetics.
To carry out the manipulation, special tools are needed: a Kassirsky needle (for sternal puncture) or a trocar needle with a mandrel (for trepanobiopsy). At the free end of the trocar there are notches that play the role of a kind of “cutter”. With the help of this “cutter”, the outer layer of the bone is “drilled” with twisting movements.
The sternal puncture needle is inserted between the third and fourth ribs in the midline. A puncture of the skin and ilium during a trepanobiopsy is done in the area of localization of the bone ridge, often to the left of the spine: this makes it easier for the doctor to manipulate.
In young children, the sternum is too thin and soft, so there is a possibility of a through puncture, which is an unfavorable complication. For this reason, a bone marrow sample is taken from the femur or tibia in children, and from the calcaneus in newborns. Other bones instead of the sternum are also chosen for biopsy in older people with severe osteoporosis and in people who take long-term corticosteroids (because of the risk of sternum fracture).
The taken punctate (biopsy) is removed from the needle and placed on a glass slide (for cytological examination) or in a vial with formalin (for histological examination). To prevent coagulation of the liquid part of the bone marrow on a glass slide, fixatives are added to the punctate.
The dimensions of the taken biopsy should allow obtaining sections for examination with an area of at least 2 × 20 mm or 3 × 15. It is very important when performing a puncture (biopsy) to take the bone marrow from the bone marrow cavity. If most of the preparation is occupied by the periosteum or subcortical bone marrow cells, a full-fledged histological examination will not be carried out: for the conclusion, it is necessary to view 5 or more bone marrow cells.
After taking the biomaterial, the needle is removed from the bone, the puncture site is treated with an antiseptic, a sterile napkin is applied and sealed with a plaster.
Possible complications
Taking a punctate (biopsy) of the bone marrow is considered a safe procedure. If it is performed by an experienced doctor and in compliance with all the rules, complications after it occur very rarely. These rare effects include:
- infection of the puncture site;
- bleeding;
- through puncture or fracture of the sternum;
- fainting and shock states in hysteroid patients.
To avoid possible consequences, the doctor must strictly observe all stages of the procedure, and before it, conduct a confidential conversation with the patient.
Recovery after manipulation
The procedure itself lasts no more than 15 minutes. After taking samples, the patient is under medical supervision for an hour: they control the pulse, blood pressure, temperature. If no complications are found within an hour, the patient is allowed to go home. Patients with pain can take painkillers.
Since dizziness and fainting are possible after the procedure, it is forbidden for the examined patients to drive a car on this day. The risk of bleeding from the skin puncture site is the reason for the prohibition to do heavy work, play sports or drink alcoholic beverages for several days after the procedure.
To prevent infection of the skin puncture site, it is necessary to change napkins in a timely manner and treat the wound with antiseptics. Until the wound heals, it is forbidden to visit public pools, saunas, swim in the river.
Cytological and histological examination
Bone marrow smears are prepared immediately after taking a puncture. A biopsy specimen for histological examination is preserved in special solutions. In the laboratory, histological sections are prepared from the biopsy, stained and evaluated. At the same time, they try to prepare as many BM micropreparations as possible, especially in hypoplastic processes, when the samples taken are very poor in cellular elements. Cytological examination is carried out on the day of sampling, histology takes up to 10 days.
In a cytological study, myelograms evaluate:
- the number and ratio of different types of cells;
- pathological changes in the shape, size and structure of cellular elements;
- type of hematopoiesis;
- cytosis;
- bone marrow indices;
- the presence of specific cells.
The result of a cytological study has the form of a table of three columns: the first contains the names of cellular elements, the second – the indicators determined in the BM samples, the third – the reference (normal) quantitative or percentage indicators.
Normal myelogram
In a bone marrow sample of a healthy person, no more than 2% of stromal cells are present: fibro- and osteoblasts, adipocytes, and endothelial cells. Among the cellular elements of the parenchyma, undifferentiated stem, blast (young) and mature cells are found. The number of blasts does not exceed 1,7%.
Five cell lineages are found in the BM:
- Erythroid (represented by erythroblasts, pronormocytes, normocytes, reticulocytes and erythrocytes).
- Platelet (it includes megakaryoblasts, promegakaryocytes, megakaryocytes and thrombocytes).
- Granulocytic (represented by myeloblasts, promyelocytes, myelocytes, metamyelocytes, stab and segmented neutrophils, basophils and eosinophils).
- Lymphoid (it includes lymphoblasts, prolymphocytes and lymphocytes).
- Monocytic (consists of monoblasts, pronormocytes and monocytes).
Cells of different germs have their own structural features and properties, for example, sensitivity to acids, alkalis or other chemical compounds. These distinctive features are used in the study of CM samples, using various dyes for processing smears and sections.
In addition to the cytological composition of BM, the rate of their maturation is also important. It is determined by determining the ratios (indices) between maturing and mature cells:
- neutrophil maturation index (norm – 0,6-0,8);
- erythroblast maturation index (norm – 0,8-0,9);
- the ratio of white and red germ cells (the norm is 3-4: 1).
In the study of trephine biopsy, the ratio between the BM parenchyma, adipose and bone tissue in sections is also determined. Their ratio is considered normal 1:0,75:0,45. Violation of these ratios indicates the pathology of the bone marrow. A histological examination is more diagnostically significant than a cytological one for BM hypoplasia, leukemia, and cancerous bone metastases.
Pathological myelogram
An increase, a decrease in the pool of individual sprouts of bone marrow cells and a violation of their ratios indicate pathology. An increase in the number of megakaryocytes in the bone marrow indicates the presence of cancerous bone metastasis. An increase in the number of blast cells by 20% or more is observed in acute leukemia. An increase in the ratio of white germ to red may indicate chronic myeloid leukemia, subleukemic myelosis, or leukemoid reactions. With a blast crisis or chronic myeloid leukemia, the neutrophil maturation index increases.
An increase in the number of eosinophils indicates allergic reactions, helminthic invasions, oncological diseases, acute leukemia, lymphogranulomatosis. Basophils grow in erythremia, basophilic leukemia, chronic myeloid leukemia. An increase in the concentration of lymphocytes is characteristic of aplastic anemia or chronic lymphocytic leukemia.
Erythroblasts increase with anemia and acute erythromyelosis, monocytes – with sepsis, tuberculosis, leukemia, chronic myeloid leukemia, plasma cells – with multiple myeloma, agranulocytosis, aplastic anemia.
A decrease in the number of megakaryocytes indicates hypo- and aplastic autoimmune processes, inhibition of CM after radiation therapy and the use of cytostatics. The ratio of white and red germs falls after heavy bleeding, hemolysis, with acute erythromyelosis and erythremia. A decrease in the erythroblast maturation index is characteristic of B12 deficiency anemia. The number of erythroblasts decreases with aplastic anemia, red cell aplasia of the bone marrow, after radiation and chemotherapy.
The cost of taking bone marrow samples by sternal puncture or trepanobiopsy followed by a myelogram ranges from 1 to 3 thousand rubles. The price depends on the form of ownership of a specialized laboratory, the method of sampling and the scope of CM studies (cytology, histology).