Anal stimulation can lead to orgasm
A minority of men and women can respond orgasmically to anal sex without direct genital stimulation. Women probably do so through pelvic muscle contractions - and a small minority even though the sheer excitement of being anally penetrated. When men experience an orgasm from anal stimulation, they tend to focus on the prostate. No doubt they are also responding to indirect stimulation of the penile bulb.
Orgasms from anal stimulation are most likely to occur when the participants become thoroughly absorbed in their sensations and fantasies. A most certain way to prevent such an orgasm is to be become determined to have one. Seeking an anal orgasm will create new pressures and disrupt the pleasure.
It must be remembered that most people require direct genital stimulation in order to climax. On the other hand, a few people have orgasms only with anal stimulation.
Anal stimulation, including intercourse, is not painful if done properly.
The belief that anal stimulation, especially intercourse, has to hurt is a persistent and dangerous myth. Just as pain anywhere in the body indicates that something is wrong, so is the same true of the anal area. With its high concentration of nerve endings, the anus can produce extreme agony when it is mistreated. Yet it can be a source of great pleasure.
When a finger, object or penis is introduced into the anus, the anal muscles go into spasm, as if fighting off an invasion. Pain will result if the partners do not wait for these muscles to relax. Under sufficient stress they will eventually collapse and the pain subsides, unless further damage is done. But, any 'pleasure' afforded from this kind of activity derives mostly from the absence of discomfort.
Maximum anal pleasure requires the elimination of all pain or physical trauma from the anal experience. Self-protection on the part of the passive partner involves being ready to say "no" until he or she is ready to proceed. Readiness is a combination of physical relaxation, usually helped along by plenty of leisurely anal touching, and desire.
Occasionally the anal muscles are relaxes, but the passive partner is still not in the mood. Stimulation should mount only in proportion to the degree of receptivity.