If there is one thing that scares many people about surgery, it's the potential to wake up during it. While it's unlikely, it certainly is a possibility in a couple of circumstances.
General anesthesia is used to prevent you from recalling anything that happens during surgery. This prevents some forms of emotional trauma and helps prevent anxiety and distress during the surgery itself. Other types of anesthesia don't make patients forget. Instead, they only make them relaxed and tired. Some sedate patients but don't necessarily cause memory loss.
The postoperative recall of intraoperative events, or the recall of what happened during surgery, is incredibly uncommon but possible if the anesthesia is not delivered correctly. Awareness occurs in around one out of every 1,000 patients. Essentially, patients start to wake up due to a lack of anesthetics in their systems. Most people go back to sleep quickly as more drugs are delivered, but some continue to wake. If a patient wakes up during surgery, the anesthesiologist takes steps to quickly put the patient under anesthesia again.
Sometimes, patients suffer from awareness because they're too ill to receive as much anesthesia as necessary. This is particularly common if a patient has heart problems, since too much of the mixture of anesthetics could cause low blood pressure and other related problems. Other patients are simply resistant to anesthesia and may wake up quicker than others. If you wake up during your procedure, it's worth talking to an attorney; mistakes may have been made that need to be addressed, and you should have the right to compensation for any trauma you've suffered.
Source: The Conversation, "Why some people ‘wake up’ during surgery," accessed Nov. 08, 2017