Leeches have been used medicinally for centuries, with their most well-known role in the former practice of blood-letting. In modern medicine, however, the medicinal leech (Hirudo medicinalis) has found a niche role in plastic/reconstructive surgery where it can be used to reduce venous congestion and encourage microcirculation.
Specially prepared leeches are attached to the relevant part (e.g. at-risk surgical flap) and allowed to feed. Once gorged they detach themselves and are collected for re-use. Heparin wipes may be used at the bite site to prolong the therapeutic anticoagulation effect.
At our centre, collected leeches are prepared for re-use by placing in them saline – apparently this encourages them to regurgitate their initial feed. Subsequent feeds are less effective, so after 1-2 feeds the leech is “retired” using concentrated saline and flushed down a sluice sink.