Bone marrow (KM) is the most important hematopoietic (myeloid) tissue of the human body. It multiplies and matures stem cells - the precursor cells of all blood cells: erythrocytes, leukocytes, platelets. They are the main component of the bone marrow. The bone marrow is inside all the bones of the human body. The bones have a porous structure, densely penetrated by permeable vessels into which young blood cells easily fall.
There are two types of CM: red and yellow. Mass KM is about 4.6% of the total weight of the person. At the same time, the weight of the red and yellow types in the bones is approximately the same. Red bone marrow is deployed in the bones of the pelvis, flat bones, the ends of the tubular bones and vertebrae. It is in it that blood formation processes take place.
The yellow type is localized in the cavities of the tubular bones and is a fatty tissue that serves as a reserve for the red type KM. Under the conditions of an acute shortage of young blood cells, the yellow brain transforms into red and hematopoiesis begins in it.
Myelogram is the result of an in vivo qualitative and quantitative study of the tissue and cellular composition of the bone marrow. The term comes from the words of Greek origin and literally translates as “bone marrow record”. The interpretation of the results of the study of a smear or punctate KM is made in the form of a table in which the percentage of different cells is presented.
Unlike blood, a portion of which can be easily taken for analysis from peripheral vessels, CM is not available for simple sampling. To perform his research, it is necessary to perform a puncture or a biopsy of the bone. This manipulation for the hematologist is not complicated, but requires special tools and appropriate qualifications of a doctor, so it is not carried out in ordinary clinical laboratories.
To conduct myelogram requires red KM. You can get a sample of it by puncture of the sternum (sternal puncture), biopsy of the ileum (trephine biopsy), heel, femoral or tibial bones.
The first two procedures for sampling a biomaterial are most often used in hematology. Trepanobiopsy allows you to get a large amount of biomaterial for research. Taking samples of CM from the calcaneus and other leg bones is used in newborns and young children.
Indications and Contraindications
The purpose of the study KM is to identify violations of hematopoiesis. Myelogram study is shown when:
- anemia (other than iron deficiency) and cytopenia;
- unreasonable increase in ESR in the total blood count;
- acute and chronic leukemia;
- lymphogranulomatosis and non-Hodgkin lymphomas;
- metastasis of malignant tumors in the bone;
- hereditary diseases (Nimman-Pick, Gaucher, Urbach-Vite diseases);
- splenomegaly of unknown origin.
Puncture of the bone marrow is carried out to establish the stage and phase of leukemia, their differential diagnosis with leukemoid reactions. Myelogram study is shown 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, asphyxiation, in hypertensive crisis.
Preparation for the procedure
The procedure for taking CM is usual for 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 must be examined before the manipulation (complete blood count, coagulogram);
- in a few days, they will cancel anticoagulants and antiplatelet agents, as well as all other medicines, except vital ones;
- for several hours, the patient cannot eat or drink (if the procedure is scheduled for the second half of the day, the patient needs a light breakfast in the morning);
- 2 hours before the manipulation it is necessary to empty the intestines, and directly in front of it - the bladder;
- if there is hair in the place of the future skin puncture, they are shaved off.
The presence of any allergies from the patient should be notified to the doctor, especially if it is an allergic reaction to local anesthetics.
On the day of taking the biomaterial, the patient cannot 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 the pain in this place is not felt.
Immediately before the procedure, the patient is given informed consent for the manipulation: he is explained the course of its performance, 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.
Bone marrow puncture
The patient is placed on a couch: with a sternal puncture, on a back (between the shoulder blades, a cushion is placed), with trepanobiopsy, on the right side or abdomen. The puncture site is treated with an alcoholic solution of iodine and anesthesia is performed with the help of local anesthetic preparations.
To carry out the manipulation, you need special tools: a Kassirsky needle (for sternal puncture) or a trocar needle with mandrin (for trephine biopsy). At the free end of the trocar there are notches that play the role of a kind of "cutter". With the help of this “milling cutter”, the outer layer of the bone is “drilled” with twisting movements.
The needle during sternal puncture is inserted between the third and fourth ribs along the median line. The puncture of the skin and the ilium during trepanobiopsy is done in the area of localization of the bone crest, more often to the left of the spine: this makes it easier for the doctor to manipulate.
Small children have sternum too thin and soft, therefore there is a probability of its through puncture, which is an unfavorable complication. For this reason, a bone marrow sample is taken from children from the femur or tibia, and from newborns from the heel bone. Other bones instead of the sternum are also chosen for biopsy taking in elderly people with severe osteoporosis and in people who take corticosteroids for a long time (due to the risk of sternum fracture).
Taken punctate (bioptat) is removed from the needle and placed on a glass slide (for cytological examination) or in a bottle with formalin (for histological examination). To avoid clotting of the liquid part of the bone marrow on the slide, clamps are added to the punctate.
The size of the biopsy taken should allow to obtain sections for a study area of at least 2 × 20 mm or 3 × 15. It is very important during the puncture (biopsy) to take the bone marrow from the bone marrow cavity. If in the preparation a large part will be occupied by the periosteum or subcortical bone marrow cells, a full-fledged histological study will not be conducted: a conclusion requires viewing 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 the tape is sealed.
Taking 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;
- penetrating puncture or fracture of the sternum;
- fainting and shock conditions in hysterical patients.
To avoid possible consequences, the doctor must strictly observe all stages of the procedure, and in front of it - to 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: pulse, blood pressure, temperature are monitored. If no complications are found within an hour, the patient is allowed to go home. With pain, patients can take painkillers.
Since dizziness and fainting are possible after the procedure, the examined patients are prohibited to drive a car on that day. The risk of bleeding from the puncture site is the reason for the prohibition to perform hard work, play sports or use alcoholic beverages for several days after the procedure.
In order to prevent infection of the skin puncture site, it is necessary to promptly change wipes 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. Biopsy for histological examination canned in special solutions. In the laboratory, histological sections are prepared from the biopsy specimen, stained and evaluated. At the same time, they try to prepare as many KM micropreparations as possible, especially during hypoplastic processes, when the samples taken are very poor in cellular elements. Cytological examination is performed on the day of sampling; histology requires up to 10 days.
Cytology myelogram evaluate:
- the number and ratio of different types of cells;
- pathological changes in the shape, size and structure of cellular elements;
- type of blood formation;
- bone marrow indices;
- the presence of specific cells.
The result of the cytological examination has the form of a table of three columns: in the first are the names of the cellular elements, in the second - the indicators defined in the CM samples, in the third - the reference (normal) quantitative or percentage indicators.
In a sample of bone marrow of a healthy person, no more than 2% of stromal cells are present: fibro and osteoblasts, adipocytes, 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%.
In CM, five cell sprouts are found:
- Erythroid (represented by erythroblasts, pronorocytes, normocytes, reticulocytes and erythrocytes).
- Platelet (this includes megakaryoblasts, promekakaryocytes, megakaryocytes and thrombocytes).
- Granulocyte (represented by myeloblasts, promyelocytes, myelocytes, metamyelocytes, stab and segmented neutrophils, basophils and eosinophils).
- Lymphoid (it includes lymphoblasts, pro-lymphocytes and lymphocytes).
- Monocytic (consists of monoblasts, pronorocytes and monocytes).
Cells of different shoots 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 samples KM, using a variety of dyes for the treatment of smears and sections.
In addition to the cytological composition of CM, the rate of their maturation is also important. It is determined by determining the ratios (indices) between the maturing and mature cells:
- neutrophil maturation index (norm - 0.6-0.8);
- index of erythroblast maturation (norm - 0.8-0.9);
- the ratio of white and red germ cells (the norm is 3-4: 1).
In the study of trepanobioptate also determine the ratio between the parenchyma CM, adipose and bone tissue in sections. A normal ratio is 1: 0.75: 0.45. Violation of these ratios indicates a pathology of the bone marrow. Histological examination is diagnostically more significant than cytological, in case of CM hypoplasias, leukemias, and cancer metastases in the bone.
Increase, decrease in the pool of individual sprouts of bone marrow cells and the violation of their ratios indicates pathology. An increase in the number of megakaryocytes in CM indicates the presence of cancer metastasis to the bone. An increase in the number of blast cells by 20% or more is observed in acute leukemia. An increase in the ratio of white to red can indicate chronic myeloid leukemia, subleukemic myelosis or leukemoid reactions. In blastic 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 with erythremia, basophilic leukemia, chronic myeloid leukemia. Increased lymphocyte concentrations are 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 myeloma, agranulocytosis, aplastic anemia.
The decrease in the number of megakaryocytes indicates hypo-and aplastic autoimmune processes, the inhibition of CM after radiation therapy and administration of cytostatics. The ratio of white and red sprouts falls after heavy bleeding, hemolysis, in acute erythromyelosis and erythremia. A decrease in the maturation index of erythroblasts is characteristic of B12-deficient anemia. The number of erythroblasts decreases with aplastic anemia, red cell aplasia KM, after radiation and chemotherapy.
The cost of the procedure for taking samples of bone marrow by sternal puncture or trepanobiopsy with subsequent myelogram ranges from 1 to 3 thousand rubles. The price depends on the form of ownership of the specialized laboratory, the method of sampling and the amount of research in CM (cytology, histology).