Heewon went through a range of emotions, with everyone saying "it's nothing”, his aunt brought up the topic of general anesthesia out of the blue (used most of the time in serious surgeries).
When he said, "if it wasn’t a big deal, why use general", it showed that he may not know what "uterine fibroids" are (which he looked up on Google right after the call), but he’s not ignorant. It emphasizes that if you're saying it's not a big deal, why use something that suggests it's serious.
Heewon is their son, nephew, so it's normal to lie to his loved ones to avoid worrying them.
Personally, I don't think if something happened to someone in your circle (which I hope never does), you'd just stay "chill".
Ye ye I getchu, I think I was genuinely projecting at the time
Wdym if it wasn't a big deal why use general anaesthesia, bro do you expect them to not use pain relief and have her awake during the entire procedure ? It's just a surgery dude chill