BACKGROUND: Leeches are commonly used in reconstructive surgery for the treatment of venous congestion in flaps. Documented mechanisms of action are: 1) injection of the anticoagulant hirudin; 2) active suction of blood; and 3) passive oozing of the bite wound. Even though the benefits of leeches in venous congestion are widely accepted, little is known about their effects in mixed arterio-venous insufficiency.
METHODS: 30 Wistar rats were randomized into 3 groups (n=10 each) and 9x3cm ischemic random skin flaps were elevated on the rat dorsum. Group 1 served as controls. In group 2, one leech was applied to the distal part of the flap and in group 3, three leeches were applied, one at a time, at 8 hour intervals. Postoperatively, flap survival and perfusion were quantitated by daily planimetry and Laser-Doppler imaging.
RESULTS: The application of a single leech on postoperative day 7 did not lead to any statistically significant changes in total flap survival or tissue perfusion. Triple leech application, however, caused a significant decrease in flap survival of 6.6% at day 7 (3x leech vs. control: 45.8±8.5% vs. 52.4±8.5%, respectively) (p<0.01) and a decline in flap perfusion of 13% (3x leech vs. control: 71.3±16.6% vs. 84.3±9.3%, respectively) (p<0.01).
CONCLUSION: The data demonstrate that the application of leeches in the setting of mixed arterio-venous insufficiency can be hazardous to flap viability. Pure venous congestion with an adequate arterial supply remains the only indication for controlled leech application in the clinical setting.