The uterus can lie in different positions in the pelvis, and it may vary from one woman to another. Most commonly, the uterus lies horizontally over the bladder, as do the ovaries. As the uterus enlarges with pregnancy, or perhaps with a large fibroid, it will cause increasing pressure on the bladder, and this results in increasing urinary frequency, pressure symptoms, and perhaps lower abdominal protrusion.
The body of the uterus may be vertical, in line with the plane of the vagina, or it may be rotated towards the rectum, a condition called uterine "retroversion". The layperson term for this anatomical condition is a "tipped" uterus. This common normal variant of pelvic anatomy is present in 20-30% of women, and usually is of no consequence. I often relate its significance as similar to being left-handed!
For some women, however the retroverted uterus is very problematic. Because of its very low position in the pelvis, the body of the uterus and the ovaries are very susceptible to trauma from intercourse. From a functional point of view, one might think of the vagina as being very shallow, as the male can very easily bump the uterus and ovaries during intercourse, and this can be very uncomfortable. Vigorous forceful intercourse, especially with the female-superior position may be associated with a tearing of the support tissues to the uterus. If abstinence for a few weeks does not see the tenderness problem resolve, and if mobility of the cervix appears to be excessive and abnormal, and motion of the cervix reproduces the pain the patient experiences with sex, the diagnosis of a ligament tear should be strongly considered. Many times a patient will relate her history as outlined above, and when I ask her if she was in the female-superior position, and did it feel suddenly that "something tore", she will look at me almost with astonishment, as if I had seen it happen!!
The treatment for the problem of a symptomatic retroverted uterus is to either move the uterus to the more common "over-the-bladder" position or remove it by hysterectomy. Repositioning of the uterus is relatively simple by means of laparoscopy, it is usually successful in solving the tenderness problem, and fertility is preserved. While most women may occasionally experience deep-penetration discomfort (depending on position or where they are in the monthly cycle) the tipped uterus for some women may render them sexual cripples. Fortunately, correction is fairly simple, and effective.