Psychic Surgery

There is a standard array of superpowers in this world, with the most common being enhancements to existing human traits like strength and senses and such. You also get the odder ones like varieties of telekinesis or some kind of concussive force. Then there's the odd ones, and one of the more unique that I've encountered has been psychic surgery.

Side/Secondary Effects

Death. The body being affected usually wants to fight what's happening to it, so there's less of chance of this than you might think, but this power is someone mentally manipulating someone else's internal organs. If you push them too far out of whack, that's not going to end well.
This effect can be ameliorated by careful study of the internist's art. Be prepared to invest in a lot of really good medical textbooks, and probably a few veterinary ones as well. Knowing how to work with the body's natural processes can avoid a lot of stress on the subject and on the person using the power.
There's also arguments to be made for meditation and careful regulation of mental stress. Being able to keep calm and focused will help avoid any accidents.

Gestures & Ritual

Entirely unnecessary. In fact, Evelyn usually finds it easier not to gesture and to keep perfectly still, or else to hold the hand of the person she's attempting to affect to keep them calmer. If she's gesturing in their direction, it's for effect, to demonstrate that something is happening and she's the source.

Applied Restriction

There are a lot of shady applications to this particular ability, and fortunately for all of us those are all covered by existing laws (don't take control of someone's body, don't murder people, don't steal their organs, etc). 
Beyond that, in the three people I've observed having this particular skill, I've noticed a marked distaste for using it for anything beyond helping someone heal. I'd need more data to confirm, but considering the rather different moral standards of the three individuals, it would seem to be a restriction of the ability itself that they prefer to use it only to heal. While they're all capable of causing harm with this ability, and all three have used other tactics and techniques to hurt or even kill others, they demonstrate a marked distaste that is not necessarily present when using psychic surgery to perform the same effect.
Thus, I theorize that something about the ability affects their own body chemistry in a subtle way, that in some way reflects whatever they're doing on themselves. A small enough effect to create a dislike of what they're doing without being able to directly pinpoint the reason why.