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Aspergillosis precipitin

Definition

Aspergillosis precipitin is a laboratory test to detect antibodies in the blood resulting from exposure to the fungus Aspergillus.

Alternative Names

Aspergillus immunodiffusion test; Test for precipitating antibodies

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The sample is sent to a laboratory where it is examined for precipitin bands that form when Aspergillus antibodies are present.

How to prepare for the test

There is no special preparation.

How the test will feel

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

Your doctor may order this test if blood work revealed that you have signs of a fungal infection.

See:

• Aspergillosis
• Allergic bronchopulmonary aspergillosis
• Invasive pulmonary aspergillosis

Normal Values

The normal test result is negative for Aspergillus antibodies.

What abnormal results mean

A positive result means antibodies to the fungus have been detected. This usually means you have been exposed to the fungus at some point.

However, false-positive results are possible. For example, invasive aspergillosis often does not produce a positive result, even though Aspergillus is present.

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

Stevens DA. Aspergillosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 360.