Leeches are making a comeback as medical helpers

Worms help preserve tissue by aiding blood flow

  • Medical leeches in a jar. photo by Monarch Labs
Medical leeches in a jar. photo by Monarch Labs (Baltimore Sun )
January 23, 2011|By Meredith Cohn, The Baltimore Sun

Marc Miller survived a motorcycle crash in October near his Baltimore County home, but his foot had been dragged along the pavement and badly damaged. That injury would require both the most advanced medicine and an ancient therapy — leeches.

Trauma doctors at Johns Hopkins, the University of Maryland and other U.S. hospitals routinely use leeches as a temporary measure to keep blood flowing as new vessels grow in a damaged area. The animals kept blood moving in and out of a new skin flap sewn onto Miller's foot. They also can get blood flowing to amputated digits that are reattached. And because the leeches' saliva has a natural anesthetic, some doctors now are looking to use them to ease pain.

"They can be the difference in whether the tissue lives or dies," Dr. Scott D. Lifchez, who treated Miller and is section chief of plastic surgery at Johns Hopkins Bayview Medical Center, said about the blood-sucking worms.

The U.S. Food and Drug Administration gave its approval to market leeches as medical devices in 2004, though they had been used for many years before then. And their use appears to be growing, said Dr. Ronald A. Sherman, director of the BioTherapeutics, Education and Research Foundation, which supports the medical use of leeches and other furry, slimy and microscopic animals.

Guide dogs may be the best-known in the category, said Sherman. But others, particularly leeches and maggots that clean wounds, are gaining in popularity. Maggots are used more than 50,000 times a year worldwide, he said.

As for the use of leeches, Sherman said there is no registry or certification board for physicians in the United States, so no one can say how often they are used for medical purposes. At an annual conference hosted by his group, seminars on leeches drew 100 medical professionals last year, more than any other year.

"In other countries, use of leeches has been ongoing for centuries, but in the United States, I would call it a comeback," said Sherman, a retired University of California researcher. "The introduction of leeches for draining blood occurred in the late 1970s, maybe early '80s, but my perception is that it's getting more known."

Records of the use of leeches in medical treatment stretch back many centuries -- to a painting in an Egyptian tomb around 1500 BC, according to one study in a medical journal. Bloodletting therapies were popular in Europe during the 17th and 18th centuries, triggering shortages of the animals in some countries. Later, as medical science advanced and bacteria became the focus of treatment, the use of leeches faded. But in the 1970's, their use was revived in microsurgery, the study noted.

Sherman said the primary use today is draining congested blood in damaged appendages or skin flaps. The leeches have a natural anticoagulant that breaks up small clots and keeps new ones from forming. That allows pools of blood to drain and keeps blood flowing freely until new vessels connect.

Doctors direct the blood-suckers to a specific site — Dr. Lifchez uses Vaseline and gauze to nudge them into place. They draw blood for about 15 minutes and fall off once they are full.

The alternative might be losing the appendage or having a more complicated surgery, said Sherman, who also notes the leeches are relatively inexpensive — Carolina Biological Supply Co., one of two U.S. suppliers, sells a 2-to-4-inch leech, Hirudo medicinalis, for $19.50. (Includes instructions. Sold only to schools and businesses, company marketing materials say.) Leeches USA Ltd. sells them for under $10 when purchased in bulk. The companies do not release sales information.

At Maryland Shock Trauma Center, where many of the worst accidents and injuries in the region are treated, leeches are employed several times a year, said Caroline Connolly, a veteran nurse who works with them.

She said the leeches have been around for about 15 years and are used when blood isn't circulating well after a "free tissue transfer" — when a flap of skin, and possibly muscle, fat, vessels and even bone are moved from one part of the body to replace what was lost in the wounded area.

Even though these are medical leeches, grown in sterile environments, many patients are still "a little grossed out," said Connolly. She said she only needs to tell the patients how successful the leeches are.

And the alternative is another long and complicated surgery to try another skin flap or amputation of damaged extremities. Connolly said leeches have been used to help rebuild faces blown apart by gunfire, but mostly they are used for car and motorcycle accident victims, such as Miller.

Lifchez used a leech every six to 12 hours on Miller over several days while he was in the intensive-care unit. There, nurses could watch over him and the animals. Miller said sometimes he'd alert the staff when a leech was done feeding so it could be properly disposed of.

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