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Medical
Live Leeches
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General Information
The first clinical use of medicinal leeches (Hirudo medicinalis) occurred
approximately 2500 years ago.
This small invertebrate is particularly valuable for plastic and reconstructive
surgery since it can
produce a small bleeding wound that mimics a venous circulation in an area
of compromised tissue.
The leech produces a number of important substances which contribute to
the special property of the
bite including an anticoagulant, a local vasodilator and local anaesthetic.
These substances allow
continued bleeding normally up to 10 hours after the animal has detached.
Applying Leeches
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The animals should be applied in adequate numbers
to the general
area of maximal congestion. The head (or biting end) of the animal
can be recognized by its searching movements, while the tail end
is used mostly as a sucker for fixation. It is best to use the hungriest
(normally the smallest) leeches first. Preferably do not use forceps
forcibly on the leech. |
1. Clean patient's skin thoroughly with soap and water
to remove all substances with strong odour or taste such as traces of
operative prep fluids or saline. Rinse cleaned areas with plain water.
2. Dampen a square of gauze with water and cut a 1cm
hole in the middle. Place the gauze on the patient with the hole in close
contact with the area to be treated. This will form a barrier to prevent
the leech from wandering.
3. Steer the head of the leech to the hole in the gauze.
Attachment generally occurs quickly. However, if the leech is reluctant
to bite, make a small needle prick on the skin to produce a tiny droplet
of blood (which should result in enthusiastic attachment)
4. Once the leech is attached, it will likely remain
safely in place until fully distended. The gauze square can be removed
and used elsewhere without disturbing the animal. However, it is important
that the site be checked continuously to ensure the leech hasn't moved.
5. Leeches usually stay attached at a truly congested
site for 30 to 60 minutes. If the blood supply is poor (in which case
the diagnosis of venous congestion is probably wrong), they may detach
prematurely and attempt to wander to another site, for example, normal
skin. Leech movement can be prevented by simple physical persuasion, but
the best way to avoid wandering is to pre-cut holes in a sheet of "Op-Site"
dressing and apply this to the treatment area.
6. Leeches may simply drop off the skin when satisfied
and will not attempt to bite again. They should then be placed in a jar
and labelled with the patient's name. This will avoid confusion between
used and unused animals and prevent use on another patient. Leeches
which have been used on a patient shoud be disposed and never re-used
on a second patient.
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