The animals should be applied in adequate numbers to the general area of maximal congestion. One or two leeches may be sufficient to treat the skin of a partially degloved finger, whereas a large flap may require six or more depending on the initial clinical response. 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.
- A maximum of four hours prior to the clinical use of a leech, rinse the animal twice with distilled water and place it in a container filled with clean distilled water. Double rinsing the leech prior to use is intended to reduce the number of bacteria that may be present on the leech’s skin, thus reducing the risk of patient infection.
- Clean the patient’s skin thoroughly with soap and water to remove all substances with strong odors or tastes such as traces of operative prep fluids or saline. Rinse the cleaned area with plain water.
- Dampen a square of gauze on the patient with water and cut a 1cm hole in the middle. Place the gauze on the patient with the hole exposing the area to be treated. This will form a barrier to prevent the leech from wandering.
- Steer the leeches head 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) or try another leech. Sugar or sweet substances are not necessary.
- Once the leech is attached, it will likely remain safely in place until fully distended. The gauze square can be removed and used somewhere else without disturbing the animal. However, it is important that the site be checked continuously to make sure that the leech hasn’t moved.
- Leeches usually stay attached at a truly congested site for 30 to 60 minutes. If blood supply is poor (in which case the diagnosis of venous congestion is probably wrong), they may detach and attempt to wander to another site, for example, nearby normal skin.
- Leeches will simply drop off the skin when satisfied and not attempt to bite again. After the leech has fed and dropped off the patient, it must be segregated, anesthetized (see disposal), and discarded as any other infectious material. A leech must never be reused on the patient or any other patient.