In ancient times a small wound could cost a man his life, and a craniotomy was like a joke. Cao Cao, who was suspicious by nature, also thought that Hua Tuo was trying to take advantage of the opportunity to take his own life, so he had Hua Tuo killed. Modern medicine has made craniotomy feasible, but it is still very risky. In ancient times, there was not even a minimum of sterilization and anti-inflammatory drugs. With a craniotomy of this magnitude, Cao Cao would have died if he was not careful.
While Hua Tuo had decades of medical experience and was skilled in a wide range of treatments, he was not known to have been an expert on the subject. But even so, there is no historical precedent for open-heart treatment. And even if there were, none had survived. It is not known whether an operation on Cao Cao's head would have been sterile or whether the instruments would have been completely sterilized at that time. The hemorrhage caused by the craniotomy would have been difficult for Hua Tuo to control.
Secondly, the head is the most important part of the human body, and its internal structure is very complex. Modern medicine is not fully confident in performing craniotomies, and if the location of the craniotomy is slightly off, Cao Cao may die on the spot. In ancient times, infected wounds were fatal. Even if Hua Tuo was a miracle surgeon, he could not have performed a craniotomy under the conditions of the time. With this surgery, the chances of Cao Cao surviving were very low. If the surgery was successful, the later conditioning and prevention of infection would have been difficult to accomplish.
At the same time, Hua Tuo's craniotomy on Cao Cao is just a story from the Romance of the Three Kingdoms. If Hua Tuo had actually performed a craniotomy on Cao Cao, Cao Cao would have died. Although Hua Tuo's medical skills were recognized by later generations, it was extremely dangerous to perform such an operation under the medical conditions of the time. Even if Cao Cao didn't know anything about medicine, he would have considered the dangers of the surgery. After all, he hadn't even heard of open-heart surgery before, and even if he were anyone else, he wouldn't have agreed to it.