Imagine you’re a doctor treating a patient’s recently reattached finger.
Should you prescribe an antibiotic? No, you already did that. Pain meds? Also done. Hint: Your treatment is slimy and squishy—and alive.
Because it’s a leech!
This bloodsucking worm may have ancient origins in healthcare, but today, it’s still used in rare circumstances—like increasing blood circulation to help reattach a finger, Scott Lifchez, a plastic surgeon and interim director of the Baltimore-based Johns Hopkins Department of Plastic and Reconstructive Surgery, told us.
Lifchez, who primarily does hand surgery, said he’s used leeches three or four times over approximately 20 years. Though an uncommon technique, it’s a trick that proves a classic principle: If it ain’t broke, don’t fix it.
Patients, however, sometimes require convincing.
“Some patients [ask], ‘Isn’t this a little medieval what we’re doing here?’ And I certainly understand that,” Lifchez said. “There’s a lot of education that you need to do.”
When it’s used. The FDA approved medicinal leeches in June 2004 to treat venous congestion—a rare condition where blood pools and swells in the veins—in graft tissue. This congestion, if untreated, can cause necrosis.
The first line of treatment for this occasional issue is additional surgery, Lifchez said. If that doesn’t work, there are other tools, like anticoagulants, administered via IV. But if none of the frontline treatments work, it may be time to call in the leeches.
“It is hardly a commonplace thing, but it’s still part of what we do,” Lifchez said.
A 2018 study found that, over a six-year period, 16 out of 145 patients who got finger reattachment surgery were treated with leeches afterward for venous congestion. About 44% of the leech-treated fingers recovered.
The theory is leeches treat venous congestion in two ways. First, they suck some blood out of the swollen veins. Second, and more importantly, their saliva contains a blood thinner called hirudin.
As opposed to an IV that pumps an anticoagulant through a patient’s entire body—potentially increasing the chance of hemorrhage by thinning blood that didn’t need thinning—hirudin from a leech goes directly into the damaged tissue, Lifchez said.
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A 2022 review of 10 studies found about 61% of 298 patients who received leech therapy saw their tissue “entirely or partially salvaged.”
“The good news is, the patient can’t feel it,” Lifchez said.
How it works. Speaking of good news, the process isn’t very different from ordering other treatments.
“Despite the fact that it’s a living thing, it’s still an order that we put in the chart and we go through pharmacy,” Lifchez said.
These aren’t run-of-the-mill leeches from a random lake, though. They’re bred and raised in labs specifically to be used for medicine, delivered to doctors when needed.
This treatment differs from other drugs, however, because it has a mind of its own (literally). Medical staff have to use barriers like vaseline or gauze to physically trap the leech on the specific part of tissue they want it to bite.
Getting medical staff on board with this treatment also takes a little more work than, say, asking them to administer an antibiotic.
“I [have] had to explain to the nurse at the patient’s bedside, ‘No, this is a real thing. I’m not making stuff up here,’” Lifchez said.
Once a leech starts sucking up blood, it takes about 20–30 minutes for it to fill up and fall off, he said. Staff then wait between six to 12 hours and apply another leech.
As for where the leeches go after use? Very well-behaved leeches are taken home by patients as pets, and the others are set free to crawl around the hospital, of course!
Just kidding. The leech is put in an alcohol solution, dies, and then is disposed of alongside other hospital biohazards.
So, if you’re looking for a pet leech, it might be easiest to check out your local pond.