[wrs]

I believe it’s common in the US for the intended (and/or unintended) surgical site to be physically marked in ink before the surgery to prevent left-right mistakes.

[Smaug123]

Also in the UK. E.g. a big arrow pointing in the general direction of the site, and a dotted circle around the site itself. The low-tech ways are the best!

[dist-epoch]

I do remember reading about a case where they have marked the wrong place on the head where to drill a hole because they had the wrong patient.