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Dynamic Chiropractic – October 20, 1997, Vol. 15, Issue 22

Blood Sucking Leeches and Double Blind Studies

By Warren Hammer, MS, DC, DABCO
Periodically, I hear someone mention that chiropractic evaluations and techniques are not valid because they're not supported by randomized double blind studies. If the clinical sciences had to rely on these types of studies, both chiropractic and medicine would be out of business. These types of studies have their place, but are difficult to perform, if not impossible in some cases.

I just read an article in the American Journal of Orthopedics1 about the use of leeches in reconstructive surgery. Now, bloodletting was very popular in the 19th century, just when chiropractic was beginning. Blood sucking leeches can be traced back to 1500 BC in Egypt from paintings on Egyptian tombs.2 We all know that tribes in the Pacific area used spinal manipulations over 2,000 years ago. Hippocrates, the father of medicine, used it as well. Are the esteemed doctors using these leeches more acceptable than chiropractors? I don't think so.

Now hear this ... "Leech therapy is a well-accepted medical technique when venous congestion occurs after emergency replantation or free-flap reconstructive procedures."1 Since the leech is neither a drug nor a device, its modern use is not constrained by regulatory agencies.3 Does that mean that chiropractors could use leeches? Get ready for a new technique.

There has never been a double blind study on the use of leeches, but medicine considers it a "well-accepted medical technique." Currently, leech therapy is considered a "proven" technique for the management of venous congestion.1 The article explains that patients will accept the blood suckers after a clear explanation of the benefits, but they also have to be informed about the risk of infection and the potential need for blood transfusions. They recommend that the doctor should consider a written consent form. I wonder why?

Smith wrote in the British Medical Journal in 1991 that only five percent of medical procedures have been documented in any way in the peer-reviewed scientific literature.4 Coronary bypass surgery, glaucoma surgery and many procedures used by orthopedists were initiated with almost no supporting literature; to date, most of the procedures used do not have double blind studies. The ultimate criteria is slowly becoming patient satisfaction, for which the chiropractic profession has always been a leader.


  1. Daane S, Zamora S, Rockwell WB. Clinical use of leeches in reconstructive surgery. Amer J. of Orthopedics 26 (8):528-532, 1997.
  2. Kraemer BA. Use of leeches in plastic and reconstructive surgery: a review. J Reconstr Microsurg 4:381-386, 1988.
  3. Weinberg SL. President's page: new medicine from old -- Hirudin and the leech. JACC 23(2):544-545, 1994.
  4. Smith R. Where is the wisdom? The poverty of medical evidence. British Medical Journal 303:798-799, 1991.

Warren I. Hammer, DC
Norwalk, Connecticut

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