Leeches

Leeches have been used for medicinal purposes for 2,500 years. Their contemporary use in plastic surgery, first described in 1836, is for the relief of soft tissue venous congestion, most commonly in compromised flaps and in avulsed or replanted appendages such as the ear and finger. Leeches have proven especially useful in microsurgery, in which venous anastamoses may prove difficult. The success rate of salvaging tissue with medicinal leech therapy has been reported to be up to 70-80%. In 2004, the U.S. Food and Drug Administration approved the commercial marketing of leeches for medicinal purposes.

Medicinal leeches, typically Hirudo medicinalis, are unique in their ability to effect prolonged venous bleeding, because they inject salivary substances that have anticoagulant, antiplatelet and vasodilatory effects. These components cause bleeding for up to 24 hours, long after the leech has been removed. Leeches also release a local anesthetic, rendering bites painless.

The indication for the use of leeches is venous congestion. This diagnosis can be made by observing the following signs: cyanosis, edema and brisk capillary refill. Pricking the affected area with a needle results in dark bleeding. Intraoperative issues, such as difficulty with a venous anastomosis or undue pedicle tension, also suggest the diagnosis. When flaps are congested, other mechanical means to improve venous outflow should be considered first, including removing tight sutures, decompressing tunneled pedicles, and evacuating hematomas.

While the initial leech bite causes about 5-15 ml of blood loss, each wound can ooze an additional 50-150 ml of blood over a period of up to 24 hours. As such, the number and timing of leeches to be applied should be tailored to the area involved. Venous ingrowth can be anticipated in 3-5 days. Treatment should be continued until signs of venous congestion subside. This may take up to 10 days.

Leeches are commercially available from several sources. After receipt, leeches can be stored in the pharmacy or on the patient floor. They must be refrigerated and kept in a feeding medium (either dissolved in distilled water or a gel) that arrives with them.

A general approach is as follows:

1. Clean the skin thoroughly with soap and water. It is especially important to remove old antiseptic or other noisome substances, as they may affect the leech’s appetite.
2. Cut a 1 cm hole in the middle of a saline-moistened gauze sponge. Place this sponge so that the hole overlies the area to which the leech is to be applied.
3. Place the leech on the gauze pad such that its head (the end that tends to move the most) is against the skin. It may be helpful to place the leech in the barrel of a 5 ml syringe (after removing the plunger) and inverting the syringe against the skin so that the leech can be specifically applied.

1. Leeches will usually attach immediately. If not, prick the skin with a needle before reapplying the leech.
2. Leeches will typically remain in the same place until they are completely distended, at which point they will fall off. This usually takes 30-45 minutes. Instruct the patient’s nurse to check on the patient often so that leeches are not lost after detachment.
3. Wounds can be encouraged to bleed after detachment by occasionally scraping the eschar off.
4. Used leeches can be discarded by anesthetizing and then euthanizing them in 8% and 70% alcohol, respectively. They should be considered biohazardous and disposed of as such. If several leeches are used concurrently, it may be necessary to check the patient’s

hemoglobin/hematocrit at regular intervals. All patients should be started on an oral antibiotic while on leech therapy. Suggested antibiotics include a fluoroquinolone or amoxicillin/clavulanic acid. Patients with HIV or taking immunosuppressive medications should not undergo leech therapy because of the risk of bacterial sepsis.

Pearls and Pitfalls

Leeches should be used as a treatment of last resort when all other means of venous outflow establishment are exhausted. It is imperative to relieve a mechanical or iatrogenic cause of venous compromise.

It is critical to rule out arterial insufficiency as the cause of flap necrosis or pallor, since leeches will not work in this situation.

Flaps demonstrate significantly decreased survival after 3 hours if venous congestion is not relieved. As opposed to arterial ischemia, venous stasis tends to cause irreversible damage. Since leeches must be flown in, it is wise to anticipate their need as early as possible. We have ordered them intraoperatively in some cases.

Although leeches can be reused on the same patient, they tend not to work as well. Used leeches should not be stored with unused ones to prevent cross-contamination. Used leeches should never be applied to another patient.

The importance of an appropriate bedside manner in ensuring acceptance of and compliance with this regimen cannot be understated. Most patients are willing to accept treatment when it is explained in a thorough and confident manner. It is also critical to include nursing and ancillary staff in the discussion of leeches, as many will not have seen them used before. We have found that by observing the first application of a leech, most nurses are willing to apply subsequent leeches without supervision.

Leech Suppliers

Carolina Biological Supply Co.—(800) 262-2922

Leeches U.S.A.—(800) 645-3569, after hours: (800) 488-4400 Ext. #2475

Suggested Reading

1. de Chalain TM. Exploring the use of the medicinal leech: A clinical risk-benefit analysis. J Reconstr Microsurg 1996; 12(3):165-172.
2. Haycox C, Odland PB, Coltrera MD et al. Indications and complications of medicinal leech therapy. J Am Acad Dermatol 1995; 33(6):1053-1055.
3. Utley DS, Koch RJ, Goode RL. The failing flap in facial plastic and reconstructive surgery: Role of the medicinal leech. Laryngoscope 1998; 108(8 Pt 1):1129-1135.
4. Whitaker IS, Izadi D, Oliver DW et al. Hirudo medicinalis and the plastic surgeon. Br J Plast Surg 2004; 57(4):348-53.