Hippocrates (c. 460 BC - 377 BC), the ancient Greek physician, was the first to apply humorism to medicine. In ancient medicine, “humor” refers to a fluid or semifluid substance. According to Hippocrates, the body was made up of four humors; blood, phlegm, black bile, yellow bile. Moreover, that health and disease occurred naturally when these humors were imbalanced, either in deficiency or excess. Thus, if someone was unwell, it was a product of imbalance in their body. To cure a patient of an illness, the excess of the relevant humor had to be removed. A common treatment was bloodletting and the instrument used…leeches. Leeches were used for a wide range of ailments including headaches, gout, bruising, and brain disorders among others.

 

A decorated initial from an illuminated manuscript, showing two people in medieval clothing. One is cutting the arm of the other so that their blood runs down into a bowl.

 

Although by modern standards, most people would squirm at the thought of leeches sucking their blood and deem this tradition completely archaic, the use of leeches for medical purposes has not become wholly obsolete in the 21^st century.

The medical leech is known as hirudo medicinalis. Leeches have remarkable properties that make them useful medical tools. They improve blood flow in areas with poor blood circulation. Their saliva contains anticoagulants preventing clotting, and as they suck they reduce tension and remove blood clots. Leeches release a natural antiseptic as they bite, therefore preventing infection. Due to these properties, the medical leech has had a revival and is now farmed in the UK to aid treatment.

Medical leeches are used for microsurgery, and reconstructive and plastic surgery.  In the case of plastic surgery, when tissue is reattached, blood clots can form as blood can get congested. Leeches are used to remove this tension and reduce clotting. Microsurgery is surgery that requires an operating microscope. One of the main purposes of microsurgery is to transplant tissue from one part of the body to another and to reattach amputated parts in what is known as free flap surgery. A major part of this process is repairing small blood vessels. Leeches have become a valuable tool for microsurgery recovery, salvaging surgically irreparable venous insufficiency occurring after free flap procedures. The leech can help the blood flow in small blood vessels and prevent tissue from dying.

Tracing the history of medicine can be full of surprises, especially when treatments date as far back as ancient Greece. No wonder Hippocrates is known as the father of modern medicine.

 

References and further reading:

• NHS, University Hospitals Coventry and Warwickshire, Plastic Surgery Department, Leech Therapy.
• Royal College of Surgeons of England, Why you should love a leech: bloodletting to microsurgery, 2018.
• NHS, Oxford University Hospitals, Leech Therapy.
• Green, P. A.|Shafritz, A. B. (2010). Medicinal Leech Use in Microsurgery. The Journal of Hand Surgery., 35(6), 1019-1021. Shelfmark: 4996.620000
• Soucacos, P. N.|Beris, A. E.|Malizos, K. N.|Kabani, C. T. (1994). The use of medicinal leeches, Hirudo medicinalis, to restore venous circulation in trauma and reconstructive microsurgery. International Angiology., 13(3), 251. Shelfmark: 4535.770000
• Bloodletting zodiac man