Surgery or healing involving Amestrian alchemy requires a knowledge of the exact mass shape and size of the material to be worked with as well as an understanding of how much power to use due to the delicacy of the tissues being worked on. In order for equivalent exchange to take place, special tools for the operations are used or, in certain cases where they cannot be used, crude methods such as offering internal alchemical energy or blood as an equal exchange can be made. The amount of energy to be applied is in the slightest amounts and barest minimums.
In surgery, these special tools have a hollow center, filled with blood or alchemically charged water (created by constant flow of one's energy through the water or even blood via the very small but detailed transmutation circles in and outside the tools.) another method is to use a 'burst method medium' in where several gel capsules full of diluted anesthesia and alchemically charged water (or a blood that matches the patient's type if blood transfusions or blood loss occurs during surgery. Different from its field counter parts, this numbed version is supposedly only in hospitals and illegal to make at home due to the obtaining anesthesia to be added –the herbal method of 'numbing' is rare but legal; painful for a few brief seconds, but legal -.)
In crude field operations or cases where surgery is not needed, the 'doctor' or giver of treatment must have alchemically charged water (blood may be used, but due to the risk of infection or the patient's violent bodily reaction, it is only to be used in extreme cases of injury.) as a medium whether they use a conductor to heal or pure water stored in gel capsules to be placed in the wound, and –as needed- broken with very small bursts of energy to release the water, healing the patient although the method is referred to as the 'military's field method' due to the pain it causes the patient. (Numbing capsules may not be carried into battle to prevent allergic reactions and suicide by overdose or addiction of certain anesthetics.)
The method for surgery is simple in theory really; to envision the sewing or repairing tissues, muscles, ligament, etc. however, the procedure is draining to a person's energy and is only recommended that those with a high reserve or immense energy stores attempt these methods and become surgeons yet have extreme precision despite the vast amount of energy *a rarity in and of itself in Amestris*. Because of this requirement, the few precious alchemical surgeons and doctors are solely seen by the Führer, his family, or have died in the Ishvalan war….or so they think.