Bone Marrow Aspiration

                          Bone Marrow Aspiration

Structures of bone marrow
Bone marrow consists of :

1) Vessels-Venous sinusoids lined by endothelial cells.

2) Nerves

3) Hemopoietic cells

4)Reticuloendothelial cells

5) Fat tissue

6) Stroma

Composition of stroma:

A) Cells:

•      Macrophages

•      Fibroblasts

•      Endothelial cells

•      Fat cells

B) Extracellular matrix:

•      Fibronectin

•      Laminin

•      Collagen

•      Proteoglycan

•      hemonectin

Indications of bone marrow aspiration

A) To diagnose:

1) Red cell disorders:

            megaloblastic anemia and pure red cell aplasia.

2) White cell disorders:

            subleukemic leukemia/ aleukemic leukemia, all leukemias for FAB typing, agranulocytosis

3) Megakaryocytic disorders: ITP and other thrombocytopenia

4) Myeloproliferative disorders: Chronic myeloid, polycythemia vera.

5) Storage disease: Gaucher’s disease

6) Parasitic disease: kala-azar

7) Plasma cell disorders: Multiple myeloma

8) For iron stores

9) Metastatic deposits

10) Fungal disorders: Histoplasma

B) Assessment of response to treatment

Contraindications

•      Major disorders of coagulation- Hemophilia and other coagulation disorders.

Needles:

•      7-8 cm length

•      Well-fitting stilette

•      Adjustable guard

1) Salah

2) Klima

Marrow is obtained by

1)      Bone marrow aspitation (marrow)

2)      Bone marrow trephine biopsy (marrow+bone)

Sites of bone marrow aspirate:

1)      Sternum

2)      Posterior superior iliac spine

3)      Iliac crest

4)      Anterior superior iliac spine

5)      Spinous process of lumbar vertebra

6)      Upper end of tibia-infants

Method:

1)      position-lie in lateral position, legs flexed, thighs against abdomen to make posterior superior iliac spine prominent.

2)      Skin covering the area cleaned with iodine, draped.

3)      5 ml of 1-2% xylocaine injected into skin and then to periosteum.

4)      Guard on the needle adjusted taking into account of subcutaneous tissue.

5)      5) Salah needle along with its stylet and introduced through skin with rotary clockwise and anticlockwise movement. Needle is pushed through the cortex into medullary bone and resistance gives way as needle enters the medullary cavity. Guard prevents further pushing in of needle.

6)      6) Stylet is withdrawn and 10 ml syringe is attched to the needle. Suction is applied into syringe to draw 0.2 to 0.4 ml of marrow into syringe. Suction stopped. Do not aspirate more marrow as it may dilute marrow.

7)      9) Good marrow smears contain marrow particles as well as trails of particles. At least 6 smears are made.

8)      10) 3 smears-fixed in methanol and stained with Giemsa. 1 for iron stain. Rest used for cytochemistry/immunophenotyping as per requirement of the case.

Biopsy Technique

•       Bone marrow biopsy is usually done following this.

•       Bone biospy needle is held with palm and index finger,  stilette is locked in place. Once needle touched  bone, stilette is removed.

•       Using firm pressure, needle is rotated clockwise and counterclockwise till entering bone cavity till an adequate amount of marrow can be aspirated, 1.5-2cm in length.

•       Rotate needle along the axis to help cut specimen.

•       Pull back about 2-3mm and the insert the needle again slightly, at a different angle to obtain specimen.

•       Slowly pull out needle in clockwise-counterclockwise motion.

•       The marrow sample is removed from syringe, using a thin wire.

•       Dry tap: Failure to aspirate marrow.

•       Causes:

•       1) Myelofibrosis

•       2) Inflitration of bone marrow

•       Suggest trephine biopsy.

Evaluation of bone marrow aspirates

1)      Detailed clinical history

2)      PBS

3)      Choose smears having marrow particles and cell trails of particles

4)      Examine under scanner and low power to assess

                a) cellularity b)megakaryocytes c) metastatic carcinoma cells

5) Select the area where cells are very well spread out. Trails made by marrow particles provide enough cells to study their morphology and carry out a differential count on the smears

6) In report, PBS and bone marrow findings should be given.

1)      Differential count of marrow: At least 200-500 marrow cells are counted.

2)      Cellularity:  assessed by visual evaluation of fat and cells. Child-highly cellular with less than 25% fat, adult-40-50% fat. Reported as hypercellular, normocellular, hypocellular. Assessed in scanner and low power.

3)      M:E ratio=3:1 to 15:1

4)      Erythropoiesis: type of reaction-normoblastic/megaloblastic/micronormoblastic and dyserythropoiesis.

5)      5) Myelopoiesis: Evaluation of maturation arrest, granulation, number of blasts, degenerative changes.

6)      6) Megakaryopoiesis: number and maturation is evaluated.

7)      7) Lymphocytes and plasma cells

8)      8) Parasites

9)      9)Other abnormal cells

Possible risks:

•       Persistent bleeding and infection.

•       Pain after the procedure.

•       A reaction to the local anesthetic or sedative.