The adult brother who has undergone surgery can sign it, because the younger brother is an adult and has mature thinking ability and judgment ability to bear the future consequences. In the absence of parents and brother-in-law, the younger brother is the most capable person to sign the operation for his sister, so this is also a close relative relationship. A mature brother who can sign is more effective and responsible than others.

Legally speaking, the consent form of operation, anesthesia and power of attorney can only be signed by the patient himself, but in practice, the hospital often requires the patient himself and his close relatives to sign the consent form of operation and anesthesia. The main purpose of the hospital is to avoid the risks that may be brought by the operation, and to prevent the troubles and disputes that the unpredictable risks in the operation may bring to the hospital and medical staff.