Why Should You Remove Your Nail Polish before Surgery
Nail Polish

When you are undergoing surgery, you will have a probe placed to the tip of your finger to monitor the oxygen level in your blood. This probe would not read properly through nail polish or artificial nails. Also, if your oxygen levels drop, your fingernails would turn blue and that would signal to the surgeon that something is not right. Next time you have a surgery, make sure your nails have no polish covering them.

References:

"Why Should You Remove Your Nail Polish before Surgery?" Why Can’t You Wear Make-up or Finger Nail Polish during Surgery? N.p., 14 June 2013. Web. 17 Jan. 2017.