Nudity would be considered inappropriate in most workplaces so that’s a good standard to hold up to.

There is a grey area for scientific/medical illustration, but usually this category of illustration removes most of the unnecessary details on genitals and stylizes the image in a way that makes your brain grasp better the anatomy, even if it’s not photorealistic. Usually you work out if an image belongs to this category by context, ie. you find it in a biology book, an encyclopedia, a healthcare pamphlet etc. When doctors or scientists need to document something with photographs ( which is often the case to supplement illustrations) they’re usually considered sensitive material if it’s on the genitals and they’re not as readily available to the general public. There’s often a content warning when things get that graphic.

If your work is leaning more towards photorealism then it may not fit that criteria, and would still be considered NSFW.