In adult patients, an ideal bone marrow specimen consists of both a bone marrow aspirate (the removal of only the fluid portion, known as the marrow) and a biopsy (sample of the more solid portion, which is the bone with marrow inside). The left or right posterior iliac crest is the most commonly used site to obtain a bone marrow biopsy and aspiration (see image). The iliac crest is preferred for safety reasons, because no major blood vessels or organs are located close to this area. Typically, sampling from the iliac crest also results in less pain to the patient and is conveniently located for the clinician. Alternate sites include the left or right anterior (front) iliac crest, the sternum (involves higher risk due to location near the heart and major blood vessels), and tibia (typically used only in infants less than eighteen months old).
Depending on the local practice, the clinician collecting the bone marrow specimen can vary from a pathologist, to an oncologist or a nurse practitioner. Patient preference regarding the use of sedation may determine where the procedure is performed. Often, bone marrow specimens can be obtained in a clinic setting using only local anesthetic, such as lidocaine. Bone marrow specimen collection can also be performed under conscious sedation in an outpatient setting or on the inpatient hospital unit. Clinicians may prefer to perform the collection in the operating room (OR) under general anesthesia. This is useful for patients that may experience complications, who express extreme anxiousness of the procedure, or when the collection is performed in combination with another procedure, such as a lymph node biopsy or placement of a port.
Depending on clinician preference and belief, the sequence of bone marrow aspiration and bone biopsy sampling may vary. A clinician uses a commercial needle to obtain the samples. Either the bone marrow biopsy or the bone marrow aspirate sample is collected first. It is common to collect the bone marrow biopsy first as to avoid aspiration artifact and because the aspiration tends to be the most painful part of the procedure. However, the bone marrow aspiration can be collected first as to prevent dilution of the aspirate by peripheral blood. Separate needles and sampling locations on the posterior iliac crest can be used for each to obtain optimal aspirates and biopsies.