I don't see any very specific issues with guro stories that do not apply to all other literature. Even original Red Riding Hood is a guro story.

Maybe one thing after all: Since guro usually is about things that do not happen in real life very often or just never at all and you do not see them on TV It may be hard to imagine or understand what you are describing.

this is especially problematic for size references Like how we are supposed to know what is the size of that gargantuan cock which still somehow manages to fit in the vagina of the little girl? so you need to take extra care in describing that stuff.

If you worry about internal anatomy I guess your story will turn into scientific thesis anyway just use plain medical terms. If you worry about external anatomy I think this is not guro related.