What is a Bone Marrow Needle?

A bone marrow needle is a device used in a bone marrow transplants, a procedure used in a number of treatments for some serious medical conditions. Aplastic anemia, some immune deficiency disorders and cancers such as Hodgkin's disease and leukemia are sometimes treated with bone marrow transplants. The first step is using a bone marrow needle to remove bone marrow from the donor, which in some cases might also be the patient.

A bone marrow needle differs from other types of needles in several ways. Unlike many medical needles, most of which are used for injections, a bone marrow needle is used to extract something. These needles have design features that enable them to perform this important medical procedure. First, bone marrow needles are thicker than an average hypodermic needle, which usually are 12 gauge. Most hypodermic needles are smaller, usually at least 16 gauge.

Both types of needles are used with syringes. The syringe used with a bone marrow needle usually is significantly larger in capacity, because as much as two quarts (1.9 liters) of bone marrow and blood might be extracted from the donor or patient. The syringe for a bone marrow needle also usually is attached after the needle is inserted, rather than before the needle is inserted.

Bone marrow needles usually have a handle that is much different from those of other needle types. There are different designs from different manufacturers, but most have a stout handle to give the medical professional the grip and leverage needed to force the tip of the needle into the bone. The needles also have a special removable inner section called a trochar. This is removed after insertion to allow removal of the marrow, a process called bone marrow aspiration.

Sometimes a small amount of bone marrow is to be extracted for a sample, called a biopsy, and the same type of needle is used for this procedure. During a bone marrow biopsy, the trochar is not removed, and a small core of bone and marrow is trapped in the needle. This sample is then used for various medical tests, the results of which are helpful in the testing of potential donors.