Can I stop Prozac (fluoxetine) a few days before major surgery? I'm worried that withdrawal may affect general anesthesia or cause problems during the operation.
No reason to stop. It makes sense to keep taking medications that your system is already used to taking. Stopping Prozac (fluoxetine) might increase your anxiety, which isn't helpful when you're facing major surgery. If you need to be on a clear liquid diet prior to surgery, it still should be ok to take your medicines with a sip if water. However, stopping Prozac (fluoxetine) does not affect general anesthesia in any significant way.
Do not stop. Most drugs regularly taken by patients are stopped a day or few days before surgery and re-started as soon as surgery is done. With Prozac (fluoxetine) on board, general anesthesia is safely administered without problems. Your doctor will give you instructions when to stop and when to re-start taking Prozac (fluoxetine) and the rest of your medications.
Why stop? I am not sure there is a reason to stop.
Can continue it. Ssri's like Prozac (fluoxetine) don't seem to have known major interactions with anesthetics. Older anti-depressants like MAO inhibitors were famous for dangerous interactions with commonly used medications, though these can also be continued if certain meds are avoided. I recommend you consult with your anesthesiology team at your pre-op appointment for their specific recommendations.