Surgery in the Middle Ages was very basic and dangerous. The four main problems of surgery had not been solved:

Pain: Natural substances such as opium, hemlock and mandrake were used to numb the pain but overdoses could be fatal.
Infection: there was no understanding of germs so many patients died from infection. Hugh of Lacca used wine to reduce the chances of infection but this idea wasn't popular.
Blood Loss: surgeons cauterised wounds and worked quickly to minimise blood loss.
Anatomical Understanding: was very poor as dissection was forbidden. Therefore surgeons had little understanding of how the body works.

Barber surgeons carried out basic procedures such as blood-letting, amputation or trepanning. John of Arderne is known as the father of surgery. He managed to remove anal abscesses or fistulas, with a 50% success rate. He also developed an ointment for treating arrow wounds. Arderne tried to professionalise surgery by introducing a guild system. War helped develop surgical practice. Arderne, for example, fought in the Hundred Years War against France.

Arabic surgery was more advanced. Abulcasis, a Muslim surgeon, wrote a 30 volume book on medicine, invented 26 new surgical procedures, popularised cauterisation and also described using ligatures.

GCSE Health and the People AQA

Surgery in the Middle Ages