I would justify lack of that content by the lack of interest in that fetish, as there can't be any other reason since it is really super easy.
Maybe there is a hard part that you need to spend quite some time playing with some kind of pipe until you get everything right as I had to take quite some effort to adjust everything in that picture. using dforce to model all that can make things easier but I did not test it yet.
realistically intestines are pretty plain single color so they barely need any texturing at all. just some glossy pinkish color tube. but if you want to make them look cool you can apply some appropriate texture
here you can get some free ones if you care about that ;)http://www.sharecg.com/v/83593/gallery/7/Material-and-Shader/Will-Timmins-Procedural-Shaders
also check thsoe https://www.sharecg.com/v/87095/browse/7/Material-and-Shader/WTP3-Will-Timmins-Procedural-Shaders-for-Ira
So that's all you need to model intestines at any level of realism.
also if you make sharp bends intestines "break" making sharp bends what makes things easier.
Now the other part is the wound itself. here everything is much harder because you need to blend it with the skin and show structure if the cut skin and some general background for guts inside.
In my picture, I avoided all that by making the cut very small. So all you need is just Use Iray decal to add pictures of the wound in the desired place and then add intestines to that.
If you don't have a way to create your own iray decals you probably should ask me to share mine ;) as I created a small collection of wounds that can be used for all purposes. but they need some more organizing. >>32303 shared some useful content.
also, it matters a lot, what you want to do
like if you want to pull out intestines from the girl's belly it is one thing and if you want to do autopsy with a detailed model of her guts that another thing
For example, you could pretty easily make a series where a guy cuts girls belly with the knife then pushes his hand inside and drags her intestine out.
Sometimes you do not need to bother with much of realism especially if you do long series with many pictures nobody will bother with all those details. Here is another example of my older pictures which is constructed very primitively but it looks pretty good anyway.
By the way you may be interested in making dirty skin for girls so that they look a bit more worn out and not always squeaky clean even after being dragged through the mud LOL or maybe a bit bruised if they endured some beating.
to do that you can just use geometry shell and apply appropriate shader from the ones listed above.
adjust its opacity to the right level and you will have more realistic dirty/bruised skin