Bone marrow examinationis useful in establishing

the diagnosis of a varietyof hematological disorders

and other systemic diseases.

In adult patients, the body of the sternumopposite the second interspace

is the site of choicefor bone marrow aspiration.

Although the ilium and vertebralprocesses may be used,

the patient should be lyingas straight as possible.

The site is first swabbed with a suitable

disinfectant such as Merthiolate.

During this time,the procedure may be explained

and the patient appraised to the factthat there may be some discomfort

or pain and reassured.

The area surrounding the siteis draped with sterile towels.

A local anesthetic such as 1% propane

is administeredto the site of the puncture.

The midline of the sternum

between the second and thirdribs is located,

and the skin and periosteumare infiltrated with one

or two milliliters of the anesthetic.

A small incision is made through the skin

with a sharp pointed knife to facilitate

penetration by the bone marrowneedle while the propane is taking effect,

the external marrow needleis assembled by inserting the stylet.

Also, the syringe is checkedfor adequate suction.

A plain tip syringe is preferable.

The marrow needleis forced through the upper cortex

only by gentle pressure.

In some individuals,penetration is difficult.

In others, elderly women, for instance,the needle penetrates easily.

Great care must be takennot to penetrate both courtesies

since the great vessels lie directlybeneath the sternum at this point.

Note that the fingersof the left hand are held

against the needle collarto restrict the depth of penetration.

When the needle is feltto enter the marrow,

the stylet is withdrawnand the syringe attached.

Two tens or three-tens milliliters

of marrow are withdrawninto the dry syringe.

Smears are quickly preparedbefore clotting occurs.

Slides or coverslips may be usedin the preparation of smears.

To produce smears of proper density,some practice is required.

At least 10 smears are preparedfrom the sample of marrow.

These are stained with right stainand other special stains as indicated.

The remaining marrowis allowed to clot in the syringe

and transferredto a container of 10% formula

or other appropriatefixatives for histologic sections,

H&D, and iron stainsare usually routinely performed.

Peripheral blood smearsare prepared from a finger puncture

for comparative evaluationwith the bone marrow material.