Bone marrow aspiration and biopsy: what is it?

Blood cells originate inside the bones, a place known as the bone marrow. Tissue aspiration and biopsy are techniques that allow direct visualization.

A large part of hematological diseases can be diagnosed by this method, the benefit of which is excellent for the timely treatment of these patients. What does it consist on? Keep reading!

Why is a bone marrow aspiration and biopsy performed?

The bone marrow is a tissue specialized in the production of blood cells. These are erythrocytes or red blood cells, leukocytes, and platelets. The process is called hematopoiesis, and cells go through a complex process of evolution (differentiation), characterized by several well-defined stages.

Unfortunately, many hematological diseases have their origin in the bone marrow. These are characterized by pathological variations in the total number of cells, due to an increase or deficit in their production. Some of these diseases are the following:

  • Aplastic anemia and aregenerative anemia, in the case of red blood cells.
  • Acute lymphoblastic leukemia, in the case of leukocytes.
  • Essential thrombocytosis and thrombocytopenia vera, in the case of platelets.

What are their main differences?

Despite the fact that bone is a very hard tissue, the marrow is much softer and has a watery component that allows its extraction. Due to this phenomenon, the bone marrow aspiration and biopsy technique was developed. It allows visualize the interior of the tissue and evaluate the development of blood cells.

The main difference is that the aspirate allows obtaining the aqueous material in which some cells are suspended, while the biopsy is a solid tissue sample. Therefore, the following must be considered:

  • The aspirate allows to see the cells, their structure and alterations.
  • The biopsy allows to see a part of the bone marrow in an integral way, both the cells and the tissue in which they are housed.

Both require a specific stain for observation through a microscope. The specialist in charge of viewing the aspirates is usually the hematologist, while the pathologist is in charge of evaluating the biopsy.

Both bone marrow aspiration and biopsy facilitate the diagnosis of hematologic diseases.

What should be taken into account in case of being subjected to these procedures?

They are usually done on an outpatient basis. That is, you can go to the specialist to perform the procedure and wait for the results at home. In other cases, it may be done in patients who were already hospitalized, as part of the study plan of any hematological pathology.

Although sampling is usually done in a matter of moments, it is advisable to plan around 30 minutes for the entire procedure. This involves the administration of sedative medications or local anesthetics.

There are several areas where the puncture can be done, but It is usually done on the back of the hip (better known as the iliac crest). It can also be done in the anterior part, as well as in the sternum and the anterior border of the tibia (in early ages).

Before

The nurse or doctor will take your vital signs, especially your heart rate and blood pressure. Usually, a disposable gown is necessary in which only the area where the biopsy will be taken is exposed, whose location will depend on medical criteria.

It is recommended to remain calm and understand that it is a safe procedure and that it is for diagnostic purposes only. To avoid complications, it is necessary to notify the doctor of any of the following conditions:

  • Allergy to anesthetic or sedative drugs.
  • Pre-existing medical conditions that are prone to bleeding, such as hemophilia or any other bleeding disorder.
  • If you are taking any medications or supplements.
  • Excessive anxiety

Then

It is normal that after the needle is removed, blood begins to come out through the hole. To control bleeding, the placement of sterile gauze with a bandage that exerts sufficient pressure is sufficient.

In case you have required sedatives, it is normal to wait a few minutes in the recovery room to avoid any kind of inconvenience. Therefore, it is advisable not to drive after the procedure and to always be accompanied.

Although the pain tends to disappear with the passage of time, It is advisable to consult a doctor about controlling symptoms. In that case, he or she might recommend oral pain relievers such as paracetamol.

Despite the fact that complications are very rare, it is advisable to see a doctor if you have the following symptoms:

  • Fever (body temperature greater than 38.3 °).
  • Excessive bleeding that does not improve with direct pressure on the wound.
  • Persistent signs of local inflammation (increased temperature, redness, pain and swelling) and general malaise.

Risks associated with bone marrow aspiration and biopsy

As we discussed in the previous section, the risk of complications is very low. In the cases that occur, there is usually a medical history of pathologies that compromise proper blood clotting or the body's defense against infections (immunosuppression).

Paradoxically, the bone marrow is responsible for the production of cells responsible for both functions. The infections that are usually associated with these procedures are osteomyelitis and abscesses.

  • Osteomyelitis is the infection of the bone tissue, produced by the entry of microorganisms through the hole that was created. It is usually difficult to treat, since it requires medical and surgical interventions to guarantee adequate control of the infection.
  • In the case of abscesses, they occur around the iliopsoas muscle, as explained in this case report published in 2016. From a clinical point of view, There may be fever, tenderness in the corresponding pelvic region, and difficulty walking. In some cases, surgical drainage may be required to support antibiotic treatment.

Find out more: What is osteomyelitis?

What do the bone marrow biopsy and aspiration results mean?

Like any other supplemental study, these medical reports can include terms that are difficult to understand. Generally, the hematologist or pathologist will describe what is observed under the microscope, such as the morphology of the cells, the appearance of the surrounding tissue, the number of structures they see, and whether they are abnormally shaped or arranged.

Sometimes, and especially with biopsies, the results may suggest further testing. These may be complementary studies that the pathologist requires, such as immunohistochemistry.

When using this technique, it is possible to see some microscopic structures that allow to differentiate, for example, certain types of leukemias. It is advisable to go to the treating doctor after having received the results, especially when there is not a complete diagnosis in the medical report.

Sometimes, the doctor will require a new clinical evaluation to determine exactly the cause of the problem. Although the most conclusive study is the biopsy, both tests are required to achieve an accurate diagnosis.

After receiving the results of the bone marrow aspiration or biopsy, it is essential to see a doctor to know the diagnosis and initiate timely treatment.

Aspiration

The morphology of the cells is important. During the development of lymphocytes, for example, there are several particular characteristics that make it possible to determine whether they are developing or mature cells.

Leukemias are a type of malignant neoplastic disease (cancer) characterized by the uncontrolled proliferation of certain cells in the bone marrow. There are several types, and the main ones are the following:

  • Acute leukemias, which can be myeloid and lymphoid.
  • Chronic leukemias, which are classified in the same way as acute ones.

The difference lies in the cells involved. Acute lymphoid (or lymphocytic) leukemia is characterized by the proliferation of immature forms of lymphocytes called pre-B or pre-T blasts.

It is important to understand that the exaggerated multiplication of one type of cells tends to displace the normal growth of the rest of the structures. Thus, in cases of leukemia, it is common to find a deficiency of red blood cells (anemia) or platelets (thrombocytopenia). Both factors tend to worsen the prognosis of these patients.

Find out more: Cancer cells: everything you need to know

Biopsy

One of the most important aspects reported in these reports is the cellularity of the sample. That is, the number of cells in each group or line (red blood cells, white blood cells, and platelets). In certain cases, finding a low number of these cells implies that hematopoiesis is not being carried out correctly.

Medullary aplasia is a representative case. Due to different physical, pharmacological or infectious factors, this tissue is affected to such an extent that it is no longer able to produce blood cells. As part of the treatment a bone marrow transplant may be necessary.

One of the advantages of biopsy over aspirate is that it allows the "architecture of the tissue" to be assessed. That is, the characteristics of the space that surrounds and supports the hematopoietic cells. This space, far from serving only as a physical support, is closely linked to the correct development of cells.

Myelofibrosis is a medical condition in which this space in the bone marrow is occupied by scar tissue, through a process known as fibrosis. According to the Mayo Clinic, can be considered a very rare type of cancer which is also capable of inhibiting the proper development of normal cells.

From a clinical point of view, patients usually have the following symptoms:

  • Tiredness, weakness and paleness, due to anemia.
  • Tendency to infections, due to leukopenia (decrease in the number of white blood cells or leukocytes).
  • Bleeding disorders, due to thrombocytopenia.

What is there to remember?

Bone marrow aspiration and biopsy are safe procedures, but they must be performed under medical indication. In case of presenting the aforementioned symptoms, It is advisable to go to any doctor for a timely evaluation. If it becomes necessary, he or she may refer you to a hematologist, who is a specialist in diseases of the blood.