Canterbury DHB

Protocol for Bone Marrow Aspirate and Trephine Biopsy

Bone Marrows

Indication for bone marrow aspiration/biopsy:

• Unexplained abnormality of the blood count or
• Exclusion of malignant infiltration.

If you consider the request inappropriate, consult the Laboratory Haematologist.

Prevention of Bleeding after Bone Marrow Biopsy

Notes:

• Patients with myeloproliferative disorders have the highest risk of bleeding.
• Patients with severe thrombocytopenia do not routinely need platelet support for this procedure.
• For patients with a diagnosis of DIC, haemophilia or a history of easy bleeding or bruising, check with the patient’s consultant before proceeding.

For patients on warfarin:

• Check the INR 7 days before the procedure. If within therapeutic range (INR <3.0), and the trend is stable, it is safe to proceed.
• If a patient has recently been commenced on warfarin, or they have unstable control, check INR within 24 hours before procedure.

When performing the biopsy, apply adequate pressure for at least 5 minutes at the biopsy site and observe the patient for 15 minutes post procedure.

Collection of Sample

Anaesthetic

General anaesthesia is usually preferred for a child. In an adult, infiltration with 2% lignocaine is usually adequate. Some patients will require sedation especially for trephines. Most of these procedures are performed on the Medical Day Ward where nitrous oxide is used for sedation. It is suggested that patients take panadeine (2 tabs) prior to procedure to decrease post-biopsy pain.

Site

• Sternum: a bone marrow aspirate may be taken from the manubrium or first part of the body of the sternum. A guard should always be used at this site so that the needle does not penetrate the back wall of the sternum.
• Posterior iliac crest: this is the preferred site for bone marrow aspirates and trephines. There may be difficulties however in cases of extreme obesity.
• Anterior iliac crest: the bone here is usually hard and the marrow space sparse. This should only be used in unusual circumstances.

It is essential that all samples collected from patients are correctly labelled and that samples do not become muddled. To avoid this problem labelling of all samples must be done at the patient's bedside.

Aspiration Procedure

• The aspiration site is carefully located by palpation. Local anaesthetic (2% lignocaine) is infiltrated immediately subdermally and then over the periosteum ensuring that the site of the subsequent puncture is adequately covered. This usually requires 5 – 10 mL of local anaesthetic.
• If a bone marrow trephine is to be performed, a small nick (2 ‑ 3 mm) is made with a pointed scalpel blade. This is not usually required for a bone marrow aspirate needle. The aspirate needle is introduced until the point touches the periosteum and adequate analgesia is checked before introducing the needle through the bone cortex into the medulla. This is done with rotation of the needle and forward pressure. Usually the operator can feel the needle entering into trabecular bone. The stylus is removed and a 5 mL plastic syringe with all air excluded is firmly attached to the end of the needle. The plunger is quickly withdrawn until there is adequate marrow in the syringe. The volume required is variable. About 0.5 mL is sufficient for bone marrow slides but more will be required if the sample is being processed for cytogenetics and/or surface markers.
• When the bone marrow is in the syringe, the syringe and attached needle are removed quickly and pressure applied to the wound. Specimens for other tests are squirted into the appropriate receptacle and then the marrow is expelled in small drops to a series of slides. The excess blood is aspirated and smears and squashes made. Slides should be labelled with the patient’s name, unique identifier (NHI or DOB) and date (day,month,year).
• If a dry tap is obtained, consider collecting 2-3 bone marrow trephine specimens, one to be used for cell surface marker studies and molecular analysis and the other for cytogenetics. It is important that these samples are not put into formalin; Hams or RPMI transport media is preferred, or normal saline is acceptable. The container must be labelled to indicate that the samples are intended for cell surface marker studies/cytogenetics.

Note: The Paediatric department assumes responsibility for the collection of bone marrow aspirate and bone marrow trephine on their patients. Paediatric needles/trephines are supplied by the Paediatric department.

Bone Marrow Trephine

• Anaesthetic as for aspirate.
• A small nick is required in the skin. The trephine is introduced until the periosteum is reached and then introduced through the cortex with a rotating movement. As soon as the medullary cavity is reached the stylet is removed and the trephine further introduced with gentle pressure and rotation of the hub. The trephine sample is freed by quick rotation of the hub and/or a slight angulation of the trephine with further introduction. The trephine is removed slowly. After removal the core is expelled by introducing the special stylet through the needle end. The core is dropped into formalin solution. If the aspirate has not been successful, the trephine is first rolled on a glass slide. The pottle is labelled with patient’s details, the number of core samples collected and the estimated length of the core is entered on the bone marrow request form. The latter procedures must be performed at the bedside.
• The bone marrow aspirate slides, bone marrow trephine core and other specimens are left in Core Haematology with the request forms. The request forms are labelled with time and date specimen taken (necessary so Histology can tell how long trephine has been fixed in formalin).

Samples for Surface Markers, Cytogenetics and Molecular Oncology

• Samples for surface markers or cytogenetics are placed into RPMI transport media. Aliquots of RPMI are stored in the fridge in the treatment room.
• Two tubes are taken if both surface marker and cytogenetic testing are required.
• For ancillary tests which are not for processing immediately (i.e. for "hold" as per request form), check with the laboratory consultant of the day regarding which "hold" samples need to proceed. Update the Flow Cytometry, Cytogenetics and Molecular markers teams via phone +/- email with a table. 

  Name/NHI	Presumed diagnosis	Flow Cytometry	Cytogenetics	Molecular

Contact details

Topic Code: 43977