Vol. 12 Issue 7-8
Return of the Leeches
A Literature Review and a Case Study
The medicinal use of leeches dates to the Stone Age (200 B.C.), originally used by Nicander of Colophon in bloodletting practices to rid the evil spirits thought to cause disease. The use of leeches in bloodletting peaked in the 1830s along with the new theory of relieving the inflammation thought to cause diseases.1 These creatures were so popular that they temporarily became rare.2 Leeches were being used medicinally in many countries worldwide, including the United States, by the 19th century.1 After the 1830s, their use began to fall from favor with patients and physicians secondary to the advancement of physiology, pathology and microbiology.3 Pharmaceutical and homeopathic remedies took precedence until the 20th century, when scientists began to look deeper into leech anatomy and physiology, revealing their significant role in the treatment of venous congestion.1
Leech Anatomy and Physiology
Hirudo medicinalis, the medicinal leech, is a parasitic worm that is often green in color with brown stripes. It measures five to 10 centimeters in length but is much longer when swimming. These creatures can be found in fresh-water marshes, ponds and streams, typically underneath stones. The leech has suckers on both its cephalic and caudal ends. The caudal aspect contains a large muscular sucker that allows the leech to attach itself and remain attached during feeding. The cephalic component has a smaller sucker consisting of three jaws, each containing 60 to 100 teeth. Together, these jaws leave an incision that resembles the Mercedes-Benz logo.4
Perioral glands of the leech secrete saliva containing many therapeutic substances including anticoagulants Hirudin, the principle anticoagulant, binds to the active site of thrombin and prevents the conversion of fibrinogen to fibrin in the coagulation cascade. It is used today as an anticoagulant in the form of a FDA-approved recombinant protein known as r-hirudin. The saliva of H. medicinalis, the species commonly used and native to Southeast Asia and Europe, contains other protease inhibitors, as well.1
Leech saliva also contains clot-dissolving enzymes and compounds that inhibit platelet aggregation. Specifically, the enzyme destabilase and a prostanoid fraction of leech saliva inhibit adenosine diphosphate-induced platelet aggregation. Another substance, calin, impedes platelet-collagen interactions and von Willebrand factor-collagen binding, further inhibiting platelet adhesion.5 Histamine-like vasodilators prolong bleeding time and increase regional blood flow, and hyaluronidase helps increase the spread of all of the salivary secretions.2 Prostaglandins found in leech saliva help reduce any swelling at the site.6 In addition, the bite is painless because of a mild anesthetic found within the saliva. Ultimately, vasodilatation and anticoagulation improve blood flow at the site.1
Mechanism of Action and Technique
The leech attaches to the skin with its muscular sucker and bites the patient with three jaws. Blood is then sucked out of the patient and into the leech via stomach peristalsis. Within 30 minutes, these leeches are each capable of ingesting up to 10 times their body weight (5 mL to 15 mL) of blood. The leech detaches itself when its meal is complete, which, along with the anticoagulant factors in its saliva, allows the wound to ooze up to another 50 mL of blood. It is this continued bleeding from the site that has the most therapeutic benefit. Once the leech has finished feeding, it will be up to six months before it will feed again.2 The duration and frequency of leech therapy depends on the specifics of each case. Several leeches over many days may be required before therapy is complete. Therapy is usually considered complete once blood begins to drain into newly formed collateral vessels at the site.7 Technique in leech therapy, including application and disposal of the leeches as well as aftercare of the bite wound, is critical in minimizing complications while increasing success of the therapy (Table 1).
Medicinal Use of Leeches In Modern Medicine
The medicinal use of leeches can be beneficial in the treatment of venous insufficiency, especially in cases of microsurgery, limb reattachment and reconstructive surgery. Venous congestion or pooling leads to edema, decreased arterial and capillary blood, arterial thrombosis, tissue ischemia and often results in necrosis.3 The patient's skin becomes cyanotic, cool and hard. Though prescription medications are available, they are not always the best treatment option for the patient. This has allowed clinicians to implement leeches as an alternative therapy. Leeches are proving their efficacy through successful treatment in a variety of medical conditions other than venous insufficiency, including macroglossia,8 lingual hematoma,9,10 breast reconstruction,11 digit replantation,12,13 severed ears,14 and various others conditions.13,15 Leeches have also been used to decongest segments of the nose, lip, penis and scalp, as well as to treat cauliflower ears and periorbital hematomas.2
Complications and Contraindications
As with any treatment, it necessary to assess the risk-to-benefit ratio of leech therapy.16 There have been many success stories, but there are possible complications. The following are of the more common complications that may present with leech therapy:
• The leech won't bite
• Allergic reaction
If the leech won't bite, it may result from tobacco fumes or anesthetic, which do not appeal to the leech. Trying a second leech may resolve this problem. In up to 20% of patients, leech therapy may result in infection, commonly with Aeromonas hydrophila.1 A. hydrophila is a normal gut flora of H. medicinalis. It lives within the gut of the leech and supplies the proteolytic enzymes needed to digest blood. Infection may occur within 24 hours to 10 days after use of the leech.2 The infectious presentation could range from mild wound drainage to severe cellulitis, abscess formation, necrosis of the skin and subcutaneous layers, myonecrosis and/or septic shock.17 To decrease infection, it is suggested to allow the leech to drop off the patient by itself.
Antibiotic prophylaxis, especially in immunocompromised patients or patients with impaired arterial circulation, is also recommended. Suggestions include a third-generation cephalosporin, aminoglycoside or tetracycline.1 The use of cefotaxime or ciprofloxacin has also been successful as prophylaxis against A. hydrophila.18
Reuse of the leeches is not practiced due to the possibility of disease transmission from one patient to another.19 Poor clinical technique has resulted in leech migration away from the treatment site. If the leech attaches itself to fresh tissue, its head should be gently stroked with a moistened pad of saline solution. The leech will spontaneously detach itself because it cannot tolerate this solution.7 Monitoring the leech throughout the treatment process is an absolute must to prevent migration through body orifices, such as the upper airways, rectum or genitourinary tract.19
Anemia is a common complication with leech therapy. About one half of patients may require a blood transfusion because of a low hematocrit. Hemoglobin and hematocrit levels should be monitored throughout the treatment process.1 Allergic reactions, though rare with H. medicinalis, have been reported with other leech species.2 Topical allergic reactions and anaphylaxis are possible and are thought to be related to proteins in the leech saliva.
Repeated use of leeches may lead to excessive scarring; this may be an acceptable complication when one considers the alternative, such as losing a digit.19 Despite these possible complications, leeches provide an additional, and sometimes superior, treatment option.
A major contraindication to leech therapy is arterial insufficiency. Doppler ultrasonography should be implemented before the use of leeches to rule out this condition. Without adequate blood supply to the site, the leech is rendered useless because it will not be motivated to bite. Clinical indicators of arterial insufficiency will also differ from those of venous insufficiency (Table 2). Another precaution with leech therapy is its use with immunosuppressed patients. These patients run the risk of an overwhelming bacterial infection. If leech therapy is considered for immunosuppressed patients, antibiotic prophylaxis should be used prior to the therapy.2
A 25-year-old white man presented to the emergency department for multiple injuries sustained in a motor vehicle accident. The patient was ejected from the vehicle through the windshield, which severed his right ear. Following initial evaluation by the trauma physicians, a decision to consult a plastic surgeon was made. A local plastic surgeon examined the patient's ear. It was noted that the ear was only attached by a small piece of tissue and was not receiving any circulation. At this point, the ear was essentially dead. The patient had two options for treatment: The ear could be completely cut off, or it could be reattached using microsurgery. The latter was chosen.
Within four hours of the patient's presentation to the emergency department, the ear was replanted. The surgeon was unable to find any veins for anastomosis and could only anastomose the superior blood supply of the ear to the temporal artery using standard microsurgery procedures. This anastomosis was confirmed with a Doppler, which produced an audible pulse over the arteries. Two Penrose drains were placed around the ear.
Leeching was then implemented per protocol. The ear was pricked with a needle to attract the leeches. Only one leech was applied at a time. The ear was allowed to continue to bleed therapeutically after the leech detached itself. For the first two days, about four to six leeches were applied individually every 24 hours. This was then decreased to three leeches every 24 hours for the next five days. A total of seven days of leeching was utilized, because there were no veins to anastomose and drain the ear. After seven days, new veins began to form on their own in order to relieve the venous congestion.
The patient did not require a blood transfusion throughout this process. However, the leeching was done on an inpatient basis, in this case because of the other injuries sustained in the accident. Aspirin and dextrin were given on postoperative day 4 for their antiplatelet activity. The patient did receive antibiotic prophylaxis throughout the leeching process and for an additional 10 days at home with ciprofloxacin and cephalexin.
One Penrose drain was removed before the patient was sent home. The other drain was removed one week following discharge. The patient continued to be followed at one, two and six months postoperatively. No complications ensued, and the patient's ear remains aesthetically pleasing.
A Medical Comeback
Though thousands of years ago they were used for different reasons, leeches today remain a vital aspect of medicine. Leeches have achieved significant results when used in microsurgery, limb reattachment and reconstructive surgery. With further research, these creatures will, and have already begun, to show promise in other areas of medicine including the relief of osteoarthritis pain.20 Leeches are making a comeback in modern medicine, ultimately benefiting the patients.
Michele Kauffman is the chair of the physician assistant department at Gannon University in Erie, Pa. Carrie Sue Walker graduates from the Gannon University PA program in August.
1. Marderosian AD. Medicinal leeching–past and present. Thrombosite Newsletter. January 1999;1(3):1-12. Available at: http://www.thrombosite.com/tsnews/snews1_3.html. Accessed April 22, 2002.
2. Daane S, Zamora S, Rockwell WB. Clinical use of leeches in reconstructive surgery. Am J Orthop. 1997;26:528-532.
3. Upshaw J, O'Leary JP. The medicinal leech: past and present. Am Surg. 2000;66:313-314.
4. Duke M. The Development of Medical Techniques and Treatments: From Leeches to Heart Surgery. Guilford, Conn: International Universities Press Inc; 1991.
5. Weinfeld AB, Yuksel E, Boutros S, Gura DH, Akyurek M, Friedman JD. Clinical and scientific considerations in leech therapy for the management of acute venous congestion: an updated review. Ann Plast Surg. 2000;45:207-212.
6. Lancellot M. Relying on past science: nursing implications of medicinal leech therapy. Medsurg Nurs. 1993;2:128-130,162.
7. Kowalczyk T. A low-tech approach to venous congestion. RN. 2002;65(10):26-31.
8. Smeets IMG, Engelberts I. The use of leeches in a case of post-operative life-threatening macroglossia. J Laryngol Otol. 1995;109:442-444.
9. Lee NJ, Peckitt NS. Treatment of a sublingual hematoma with medicinal leeches: report of a case. J Oral Maxillofac Surg. 1996;54:101-103.
10. Grossman MD, Karlovitz A. Lingual trauma: the use of medicinal leeches in the treatment of massive lingual hematoma. J Trauma. 1998;44:1083-1085.
11. Gross MP, Apesos J. The use of leeches for treatment of venous congestion of the nipple following breast surgery. Aesthetic Plast Surg. 1992;16:343-348.
12. Wells MD, Manktelow RT, Boyd JB, Bowen V. The medical leech: an old treatment revisited. Microsurgery. 1993;14:183-186.
13. Soucacos PN, Beris AE, Malizos KN, Kabani CT, Pakos S. The use of medicinal leeches, Hirudo medicinalis, to restore venous circulation in trauma and reconstructive microsurgery. Int Angiol. 1994;13:251-258.
14. Cho BH, Ahn HB. Microsurgical replantation of a partial ear, with leech therapy. Ann Plast Surg. 1999;43:427-429.
15. Weinfeld AB, Kattash M, Grifka R, Friedman JD. Leech therapy in the management of acute venous congestion of an infant's lower limb. Plast Reconstr Surg. 1998;102:1611-1614.
16. de Chalain TM. Exploring the use of the medicinal leech: a clinical risk-benefit analysis. J Reconstr Microsurg. 1996;12:165-172.
17. Lineaweaver WC, Hill MK, Buncke GM, et al. Aeromonas hydrophila infections following use of medicinal leeches in replantation and flap surgery. Ann Plast Surg. 1992;29:238-244.
18. Hirudensis medicinalis–medicinal leeches. Microsurgeon.org Web site. Available at: http://www.microsurgeon.org/leeches.htm. Accessed March 12, 2004.
19. Abdelgabar AM, Bhowmick BK The return of the leech. Int J Clin Pract. 2003;57:103-105.
20. Michalsen A, Moebus S, Spahn G, Esch T, Langhorst J, Dobos GJ. Leech therapy for symptomatic treatment of knee osteoarthritis: results and implications of a pilot study. Altern Ther Health Med. 2002;8(5):84-88.