The very sight of them may be off-putting, but for patients in trouble, medicinal leeches are just what the doctor ordered.
In an apparent anachronistic twist of contemporary medicine, plastic surgeons are relying on these large worms to rescue skin flaps compromised by venous congestion after surgery. Many clinicians use these blood suckers only in a last ditch effort to stave off tissue death or necrosis following reconstructive procedures, including those for cancer. However, proponents of leech therapy say that surgeons should be less hesitant to use them prior to a grave threat to the surgical site.
Known as Hirudo medicinalis, the medicinal leech, which costs about $7 per worm,
is used most often after trauma, such as the loss of a finger or limb. Hundreds of years ago,
physicians and healers around the world relied on leeches to treat everything from laryngitis to
yellow fever.
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Reattaching a digit and reconnecting its blood vessels is painstaking work that is often carried out under the microscope. Problems with reestablishing blood flow occur about 10% of the time when "we can get the artery hooked up, but not the vein," explained Louis P. Bucky, M.D., a plastic and reconstructive surgeon at the University of Pennsylvania in Philadelphia.
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By the time a leech arrives in the hospital pharmacy, it "is hungry and ready for a blood meal," said Lawrence Wallace of Carolina Biological Supply Company, Burlington, N.C., sole distributors of laboratory-raised medicinal leeches in the United States for the Welsh company Biopharm. Once the 1- to 2-inch long worm is nudged into position on the wound, it can consume up to five times its body weight in blood, approximately 10 milliliters in an hour or less. The animal's bite does not hurt, possibly due to the anesthetic compounds in a leech's saliva.
During its feast, the leech injects an anti-coagulant, known as hirudin, into the wound, which contributes to sustained bleeding of the affected site for 5 to 6 hours after the leech falls off on its own or is removed. Once it is finished dining, the leech is disposed of like medical waste.
Hirudin, which was isolated in the leech in the 1950s, has raised awareness of the leech outside the field of plastic surgery. Enzymes present in its saliva dissolve blood clots and inhibit platelet aggregation, which has led to the creation of drugs like Refludan (lepirudin), a recombinant protein used to treat heparin-induced thrombocytopenia (Hoechst Marion Roussel, Kansas City, Mo.).
There are potential hazards associated with leech therapy, such as infections caused by bacteria from the leech's gut. Yet, according to Papel, the commercial availability of the animals has dissipated many surgeons' fears that leeches will infect their patients.
Out of Sight
Excessive bleeding that requires a blood transfusion is another risk people undergoing leech therapy may face. While Bucky said patients "are remarkably understanding and reasonable about leeches," they are nevertheless apprehensive initially about having them applied to their bodies. In light of this, Bucky will erect a tent to keep the homely worm out of a patient's line of vision.
Friedman agrees with Bucky's assessment of patients' willingness to accept this unique therapy despite their reluctance. One of Friedman's patients who underwent reconstructive surgery for cancer of the vulva "was not very excited about the leeches and only agreed to let me use them if she didn't feel or see them." In the end, the woman kept her sunglasses on to prevent her from catching a glimpse of the animals crawling on her thigh.
Popularity Poll
There are signs that leeches are gaining in popularity. Wallace estimates that since the introduction of Biopharm's medicinal leeches to the U.S. in the mid-1980s, sales have increased every year. Now, said Wallace, Carolina Biological Supply Company sells "several thousands per year."
Still, according to Friedman, leech therapy is rarely discussed in medical school, meaning doctors are left to just "figuring it out" on their own. "The first time you see the leeches, you think whoever is putting them on [the patient] is crazy," he said, before noting that at times, "people tend to use them too late."
"If you have to use them," said Friedman, "don't waste time. Despite our advanced surgical techniques and therapies, there's still nothing better than leeches to solve the problem of venous congestion. I have a lot of respect for the little guys."
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