Blood test
Blood test

FTA-ABS

Definition:
A blood test that detects antibodies directed specifically to the bacteria that causes syphilis - Treponema pallidum. This test is used routinely to confirm whether a positive screening test for syphilis (either VDRL or RPR) reflects true infection with syphilis. In addition, since the screening tests may miss up to a third of cases of early (primary) or late (tertiary) syphilis, FTA-ABS may be used in these circumstances to improve diagnostic yield.

Alternative Names:
Fluorescent treponemal antibody absorption test

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 for the test:
Adult:
There is no special preparation 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 experiences, 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 the test will feel:
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.
Why the test is performed:
This test is used routinely to confirm whether a positive screening test for syphilis (either VDRL or RPR) reflects true infection with syphilis. It may also be done when either primary or tertiary syphilis are suspected and the initial screening tests are negative, as screening tests during these stages of syphilis may be falsely negative.
Normal Values:
A negative or non-reactive result indicates no current or past infection with syphilis.
What abnormal results mean:

A positive FTA-ABS usually indicates infection with syphilis. This test will remain positive for life even if an individual has received appropriate treatment.

Other illnesses such as yaws and pinta may also result in positive FTA-ABS.

What the risks are:
  • excessive bleeding
  • fainting or feeling light-headed
  • hematoma (blood accumulating under the skin)
  • infection (a slight risk any time the skin is broken)
  • multiple punctures to locate veins
Special considerations:
FTA-ABS will remain positive for life even if syphilis has been adequately treated. Therefore, it cannot be used to monitor therapy in the treatment of syphilis.

Review Date: 11/11/2001
Reviewed By: Rocio Hurtado, M.D., Infectious Diseases Division, Massachusetts General Hospital and Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2003 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.