Comparison between thermography and fluorescein test in the detection of incompetent perforating veins.

Incompetent perforating veins of the legs were located by dynamic thermography at 69 sites and by the fluorescein test at 31. All the sites were explored by multiple local incisions. Incompetence of the veins was determined by demonstrating retrograde blood flow through these veins when severed. Explorations of these sites showed that thermography detected 94% and gave false-positive results in 6%, while the fluorescein test detected 16% and contributed 84% false-positive results. These findings show a highly significant difference (P <0.0005) in favour of the thermographic technique. Detection of 16% of incompetent perforating veins by the fluorescein test is statistically insignificant. This inaccuracy is thought to be due to inadequate dermal penetration of the ultraviolet rays. A positive fluorescein test probably indicates the presence of incompetent perforating veins but has little anatomical relationship to their actual site.