What is a spinal tap?
A bone marrow puncture, also known as bone marrow aspiration, is a procedure that allows the extraction of samples of bone marrow, present inside some bones.
The bone marrow is made up of a solid part and a liquid part, liquid tissue being extracted in the puncture or aspiration, while the more solid tissue would be extracted by means of a bone marrow biopsy. Both tests make up what is known as a marrow study.
What does a bone marrow puncture consist of?
A bone marrow aspiration is performed on an outpatient basis. Normally, the bone marrow sample is taken through the sternum or pelvis. The extraction is performed as follows:
- The skin where the puncture is to be performed is sanitized and an analgesic is injected to anesthetize the area and the surface of the bone. If necessary, a sedative may also be used to help the patient relax.
- Once the puncture begins, a special needle is injected into the bone. This needle is formed by a tube that is attached to its surface, with which the liquid sample can be sucked and obtained, which will flow through the tube.
- Once performed, the needle is removed and pressure is applied to the puncture site. Subsequently, a protective bandage will be placed on the skin.
The removal of spinal fluid may cause acute pain, but only for a short time.
Why is a puncture performed?
Performing a bone marrow puncture allows detailed information to be obtained on the condition of the marrow, as well as the presence of blood cells, i.e. white blood cells, red blood cells and platelets.
This test may be requested in those cases in which the results of a blood test show abnormal results or do not provide sufficient information about what is to be diagnosed or determined.
The puncture can be done to diagnose a disease or disorder of the marrow or blood cells, to determine the status of a disease, to monitor metabolism and iron levels, and to observe or monitor the progress of treatment of a disease.
It is also used for various disorders. Some of them are the following:
- Anemia
- Blood cell disorder: leukopenia, leukocytosis, thrombocytopenia, thrombocytosis, pancytopenia, polycythemia.
- Blood and marrow cancer. Leukemia, lymphoma and/or myeloma.
- Hemochromatosis
- Fever of unknown origin
Preparation for bone marrow puncture
Normally, spinal puncture is performed on an outpatient basis and without special preparation. However, the specialist in charge of supervising the case should know if the patient is taking any medication or supplements, as some may increase the risk of bleeding in these cases.
In those cases in which the patient does not tolerate pain or feels excessive nervousness before the test, the physician may administer a sedative.
What does the spinal tap feel like?
During the procedure, the patient will feel a prick and, if an analgesic is applied, a slight burning sensation. As the needle advances, the patient will feel some pressure, and by the time the extraction begins, he/she will feel a sucking sensation, usually painful, but for a short period of time.