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RPR How the Test is Performed:
Adult or child:
Blood is drawn from a vein ( venipuncture ), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding .
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to Prepare:
Adults:
No special preparation is usually necessary.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
How it Feels:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing .
Risks:
- excessive bleeding
- fainting or feeling lightheaded
- hematoma (blood accumulating under the skin)
- infection (a slight risk any time the skin is broken)
- multiple punctures to locate veins
Why this Test is Performed:
This test may be performed when syphilis is suspected.
Screening for syphilis is usually done during the first prenatal checkup for pregnant women. This is because untreated syphilis may cause abortion , stillbirth, or neurological damage to the fetus.
Normal Values:
A negative test result is normal.
Abnormal Results:
A positive test can indicate syphilis . However, many conditions can give false positive results (see "special considerations").
Additional conditions under which the test may be performed:
Cost:
The estimated cost is $15.
Special Considerations:
Excessive hemolysis and gross lipemia can affect test results.
Many conditions cause false-positive results with the VDRL and RPR tests including mycoplasma pneumonia , malaria , acute bacterial and viral infections, and autoimmune disease.
Syphilis results from infection by Treponema pallidum. Early infections are associated with an antibody to some substance produced by the body in response to the infection (reagin). This antibody also appears in other infections, so the tests that measure it (VDRL and RPR) are not specific for syphilis (that is, there is a high false-positive rate). Later in the infection, an antibody specific to the organism appears. This antibody can be detected by the FTA-ABS test.
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.
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