The Expert:

Karen Coubray

Karen Coubray is Professional Development Team Lead for Surgical Services and Critical Care, and Nurse Educator for Plastics and Burns. She has been involved with leech therapy for 20 years.

Their View:

When it comes to treating venous congestion, when all else fails, nothing in our arsenal of medical science and technology can rival the leech.

Leeches are cold-blooded, freshwater annelids related to earthworms. Adults are about 10cms long, have 300 teeth arranged over three jaws, and are capable of biting through a hippo’s hide.

The use of leeches for blood-letting and other kinds of therapy dates back to ancient Egypt. It peaked in the early 19th century, when leeches were used for everything from tonsillitis (leech tethered to a tooth and lowered down the patient’s throat) to haemorrhoids (leech attached to the patient’s bottom).

Today, leech therapy is used primarily in plastic and reconstructive surgery as a treatment for venous congestion. Venous congestion can threaten outcomes in patients with surgical flaps or who have had a traumatically amputated body part, commonly a finger or toe, reattached.

Patients usually need leech therapy for 3-7 days, or until venous circulation improves.

A major advantage of the leech is that its bite produces a neat cut that directly exposes the patient’s underlying blood vessels. Its saliva contains an anticoagulant protein, hirudin, which promotes blood flow when the leech attaches. Leeches also inject a local anaesthetic when they bite that renders the procedure painless for the patient.

Once attached, a leech can suck 5-15ml of blood. Not only does the leech decongest blood as it feeds, but it injects a compound called calin which causes bleeding to continue for up to 10 hours by neutralising the ability of collagen to induce blood clotting. This gives the body part valuable time to re-establish its own circulation.

Leeches are not suitable for use with every patient. The primary use of leech therapy when all else fails is for treating venous congestion. Leeches should be used with caution in immunosuppressed patients, because there is a slightly increased risk of infection. Patients having leech therapy should be given prophylactic antibiotics for this reason. In addition, leeches should not be used where there is existing infection, and because there is a potential for patients having leech therapy requiring a blood transfusion, consideration needs to be given for Jehovah’s Witness patients.

Once a patient has been clinically assessed as suitable for leech therapy, it’s crucial to obtain the patient’s informed consent. Medical and nursing staff should explain that leech therapy is proven effective and safe, and that medical leeches are farmed in special conditions for medical purposes – not dug out of a swamp! Take the patient through the purpose and function of the leech, and the procedure to be used. When leech therapy is properly explained to them, most patients find it fascinating and readily consent.

The attachment procedure itself takes time. Leeches can be temperamental, and they may refuse to latch on if they are handled too much or harmed, or if saline or chemicals are present on the skin. It’s important to make sure they latch on to the right place first time, because they cannot be detached easily. Once in place, it is often a good idea to ‘fence’ the leech in using paranet or bactigras or containers taped onto the desired area to prevent wandering.

The leech will generally feed for 20-45 minutes. Monitor the leech for migration or detachment, particularly if it is attached to a part of the body that the patient cannot watch, such the face or an orifice. Monitor congested tissue for colour, capillary refill, warmth and bleeding at the site every 20-30 minutes, with a detailed site evaluation every four hours.

The leech will detach when full. If it needs to be removed before it detaches voluntarily, dip a cotton bud into chlorhexidine, saline or vinegar and stroke the leech’s head. Do not pull the leech off – this can cause the leech’s teeth to remain in the patient and become a source of infection.

Because they come into contact with patients’ blood, leeches must be used on one patient only and, once used, they will not be hungry again during the patient’s course of treatment – they can go for up to a year without feeding. To destroy a leech humanely, place it in a specimen jar of chlorhexidine and alcohol and screw the lid on.

Leeches have saved a lot of flaps and replants. They improve surgical outcomes for patients with venous congestion, are minimally invasive and not harmful to patients. They are intriguing little creatures that prove advancements in medical science and technology can’t always beat Mother Nature.

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