BONE MARROW ASPIRATE AND BIOPSY PROCEDURE
(PATIENT INFORMATION)
The bone marrow is like a factory that produces blood. Bone marrow aspirate and biopsy is a procedure to assess the function of this factory. This procedure is needed as an adjunct to a CBC and peripheral blood examination in order to confirm a suspected haematological problem on blood film or to carry out specialised tests, stains and investigations on the marrow.
This is a bedside procedure and is usually done under local anaesthesia. A valid consent is necessary outlining the steps and need for the procedure. The patient is asked to lie on his/her left side and the back is exposed upto the buttocks. The skin over the hipbone at the back is exposed (the vertebral column is not touched) This site is selected as it is not close to any major structure that can be inadvertently damaged during the procedure. Hence, there is a high safety factor here.
The area is cleaned with two antiseptic / antibiotic solutions. Then with the help of a thin needle, local anaesthesia is administered first in the skin and then upto the bone. The patient usually feels the needle as an “insect bite” at this moment. Few minutes are given for the local anaesthesia to take effect after which a special Bone Marrow Aspirate and Biopsy needle is used to enter into the bone. A sample of marrow (thick immature blood) is aspirated. At this moment the patient feels a “suction pain”(few seconds) while the marrow is drawn into a syringe. The aspirate helps us to study the quantity and quality of the bone marrow cells. After adequate marrow is collected for the various investigations, with the help of the same needle, a trephine (core) biopsy is obtained. This is a very small piece of bone collected to study the architecture of the bone, presence of features of TB, cancer or detection of the presence of any abnormal tissue (fibrous tissue).
Hence a combination of the aspirate and biopsy is always performed so as to get a better chance at diagnosis. Samples may also be collected for cultures or for advanced tests if the clinical situation demands. On an average 5-10ml of marrow is collected. This is like a drop from an ocean!
It must be clearly mentioned that this procedure is for purposes of diagnosis only and is not a treatment. It will help us to plan treatment, to assess marrow response to treatment already given and for prognosis.
As for all procedures the patient has to accept the risk of local anaesthetic reactions, which cannot be predicted even at the best of centres. Fortunately, such reactions are extremely rare. There are occasions when the marrow is not obtained due to pathological reasons (“dry tap”). In such a situation attempts are made to obtain as much marrow as possible to make slides and then a biopsy is attempted.
After the procedure is over, there is minimal dull pain at the biopsy site. The patient can get up and walk out of the clinic after resting for 15-30mins. Hence the procedure usually does not require in-patient admission unless there are compelling reasons for admission. The dressing at the site needs to be untouched for 24 hours, after which the patient can have a bath and take off the dressing. A waterproof Band-Aid can be applied daily for the next 2 days. Sometimes a very small scar (less than 0.5cm) is seen NO NSAID’s (painkillers) other than paracetamol or proxyvon are to be used. The patient must inform the doctor if there is severe pain or bleeding from the site of biopsy.