However,adequate length of a unilateral biopsy may obviate the need for bilateral examination .In one study,a biopsy length of 19.5 mm was the smallest acceptable length,leading to a 50 percent chance of detecting bone marrow stases [36 tudy concluded that one 20 mm-long specimen could obviate the need for bilateral bone marrow sampling in patients being evaluated for the presence of diffuse large B-cell NHL [37]. TECHNIQUE Materials-The supplies necessary for a bone marrow biopsy and aspiration.with the exception of sterile gloves and vials for specific studies on the collected samples,are conventionally packaged in a single tray.The contents should include all of the following: .Povidone-iodine antiseptic solution for cleansing the chosen site,along with the necessary drapes to maintain sterility at the site A1 or 2 percer lidocaine solution for local anesthesia,along with a sterile syringe,a 23-gauge and a 21-gauge needle .A number 11 scalpel blade for making the skin incision prior to inserting the aspiration and biopsy needles .Sufficient quantities of sterile gauze and bandages to clean the biopsy site and to apply local pressure to insure hemostasis wi hen the proced ure has been completed .A large selection of needles used for aspiration is available.a needle with a stylet that can be fixed in place initially and removed later is oreferred.it is important to use a sharp needle.as well as one long enough to penetrate through the subcutaneous tissues and into the marrow cavity.A needle osen for stemal aspiration should be shorte than one used for aspiration at the iliac crest.and should be equipped with a guard to insure controlled entrance into(and not beyond)the stemal marrow cavity (see'Sternal aspiration'below). .Jamshidi biopsy needle with stylet and a device (obturator)for removing the biopsy core from the needle with amage to e specimen Posterior iliac crest-Proper bone marrow aspiration and biopsy requires strict attention to detail.The following items should be completed in the order in which they appear .Administer any necessary premedications(anti-anxiolytics or pain medications)(see 'Premedications'above). .The patient should be placed in either a prone or lateral decubitus position.In heavier patients,a lateral decubitus position with the knees However, adequate length of a unilateral biopsy may obviate the need for bilateral examination: ●In one study, a biopsy length of 19.5 mm was the smallest acceptable length, leading to a 50 percent chance of detecting bone marrow metastases [36]. ●Another study concluded that one 20 mm-long specimen could obviate the need for bilateral bone marrow sampling in patients being evaluated for the presence of diffuse large B-cell NHL [37]. TECHNIQUE Materials — The supplies necessary for a bone marrow biopsy and aspiration, with the exception of sterile gloves and vials for specific studies on the collected samples, are conventionally packaged in a single tray. The contents should include all of the following: ●Povidone-iodine antiseptic solution for cleansing the chosen site, along with the necessary drapes to maintain sterility at the site ●A 1 or 2 percent lidocaine solution for local anesthesia, along with a sterile syringe, a 23-gauge and a 21-gauge needle ●A number 11 scalpel blade for making the skin incision prior to inserting the aspiration and biopsy needles ●Sufficient quantities of sterile gauze and bandages to clean the biopsy site and to apply local pressure to insure hemostasis when the procedure has been completed ●A large selection of needles used for aspiration is available. A needle with a stylet that can be fixed in place initially and removed later is preferred. It is important to use a sharp needle, as well as one long enough to penetrate through the subcutaneous tissues and into the marrow cavity. A needle chosen for sternal aspiration should be shorter than one used for aspiration at the iliac crest, and should be equipped with a guard to insure controlled entrance into (and not beyond) the sternal marrow cavity (see 'Sternal aspiration' below). ●Jamshidi biopsy needle with stylet and a device (obturator) for removing the biopsy core from the needle without damage to the specimen. Posterior iliac crest — Proper bone marrow aspiration and biopsy requires strict attention to detail. The following items should be completed in the order in which they appear: ●Administer any necessary premedications (anti-anxiolytics or pain medications) (see 'Premedications' above). ●The patient should be placed in either a prone or lateral decubitus position. In heavier patients, a lateral decubitus position with the knees