Long ago, doctors took blood from sick people. 

Long ago, doctors took blood from sick people. 

For over 2,000 years, doctors used a way to treat sickness called bloodletting. 

Some doctors used leeches, which are small worms. Others used a tool called a scarificator. 

Bloodletting was a medical practice used for over 2,000 years. 

This system worked by looking for an imbalance in the humors. Doctors thought that too much blood caused a condition called plethora. This could lead to a fever, a headache, or apoplexy. To fix this, a physician would remove the extra blood. They might use a specific vein based on the illness. For example, they might use a vein in the right hand for liver problems. They might use a vein in the left hand for spleen problems. 
Many different people studied and used bloodletting throughout history. In Ancient Egypt, people may have used scarification to bleed patients. In Greece, a physician named Hippocrates mentioned the practice in the 5th century BC. Later, the Roman physician Galen became very influential. He believed blood was the most important humor to control. During the Middle Ages, Islamic medical authors also advised bloodletting for fevers. In the 1600s, the practice became part of a group of treatments called heroic medicine. 
There were several ways that doctors actually performed bloodletting. One way was phlebotomy, which means opening a large vein. Another way was arteriotomy, which involved puncturing an artery. 

Today, we know that traditional bloodletting is a pseudoscience. 
Bloodletting is the deliberate withdrawal of blood from a patient to prevent or cure various illnesses. 
The practice was rooted in an ancient medical theory regarding the four humors. These humors were bodily fluids that had to remain in a specific balance to maintain health. The four humors included blood, phlegm, black bile, and yellow bile. These fluids were thought to correspond to the four Greek classical elements: air, water, earth, and fire. Physicians believed that an imbalance, such as an overabundance of blood called plethora, caused disease. Symptoms of plethora were thought to include fever, headache, and apoplexy. To restore balance, a doctor would remove the excess blood to treat the patient.



Medical history shows many different cultures utilized these techniques. In Ancient Egypt, evidence suggests bloodletting by scarification was an accepted practice. Some accounts suggest Egyptians may have based this on observations of hippopotamuses. In Greece, the physician Hippocrates mentioned the practice in the 5th century BC. Later, the Roman physician Galen became a major influence by advocating for physician-initiated bloodletting. Galen discovered that both veins and arteries were filled with blood. He believed blood was created and then used up rather than circulating. He also developed a complex system to decide how much blood to remove based on a patient's age, the season, and even the weather.



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