Evaluation of VDRL test in Sudanese blood donors.

2201 blood donors and 199 patients with sexually transmitted diseases (STD) were tested with the Venereal Disease Research Laboratory (VDRL) and the fluorescent treponemal antibody-absorption (FTA-ABS) tests. The VDRL test was found positive in 30 (1.36%) of the blood donors and 11 (5.5%) of the patients. Syphilis was confirmed by FTA-ABS test in one patient (0.5%) but not in blood donors. The biological false positive (BFP) reactions were 1.36% in blood donors and 5.0% in control patients. The place of VDRL test as a screening test for syphilis and the low rate of its seroreactivity among blood donors was discussed. The BFP reactions were reviewed to assist in the interpretation of the VDRL test which was evaluated on the basis of the control specimens. It was concluded that syphilis should be excluded before blood is transfused and the VDRL test should remain the screening test of choice in the blood transfusion service.