The pelvis is very important in female reproduction because it houses most of the reproductive organs. Due to this same fact, pelvic inflammatory diseases (PID) have been known to be a frequent cause of infertility among women. In most cases, the infection of the pelvis starts off as a sexually transmitted disease (STD) caused by either gonorrhoea or chlamydia infections of the cervix. These infections are usually without symptoms, or in worst cases, cause some cervical discharge. The bacteria responsible for these infections could, from the cervix, ascend into the uterus and fallopian tubes causing a painful infection and an accumulation of pus in the tubes.

The ascension of the infection can be stooped by the use of antibiotics in the early stages, though, the normal body defence, with or without antibiotics, will act by forming a walled-abscess over, and to contain, the infectious bacteria. The abscess will eventually resolve in either of two ways. The abscess cavity would either become sterilized, the fluid eventually cleared and the abscess then goes away, which is better, or it ruptures and the infection then spreads further to cause more abscesses, which is very bad for fertility.

To get a better picture of how pelvic diseases affect fertility, you should note that, once a pathogenic bacteria such as gonorrhoea or chlamydia gets access above the cervix to the uterus and uterine tubes, if not stopped by the use of antibiotics or arrested by the body's immune system, the inside surfaces of the tubes become denuded of their skin called the epithelia lining. Several white blood cells, in their attempt to contain the infection, form a closed cavity around the pathogenic bacteria. This space becomes so filled with the multiplying bacteria and fluids that that area of the tube become filled with pus.

Even if treated at this stage, the damage has been done. The destroyed lining of the tube may cause gluing together of the walls of the tube, causing blockage of the tube later, to both egg and sperm cells. For pregnancy to occur, the sperm cells and the ovum must meet in the tubes for fertilization to occur and the product of fertilization must be transported from the tube to the uterine cavity on time for implantation. So, even if the tubes don't get blocked by agglutination of their walls due to stickiness caused by past infections, the destruction of the tubal lining still affect fertility because the ciliary wave motion of the tubes that serve to move the fertilized ovum down to the uterus right on time for implantation, is lost.

What could be worst is that, if the tubal abscess opens or leaks from the end of the tube, the ovary at that end of the tube may stick to the tube and become the far wall of another abscess cavity, which is now bigger and more destructive. This is called a tubo-ovarian abscess and it causes a complete obliteration of fertility on the side it occurs, since the tube, ovary and all its eggs are destroyed.

It is estimated that 5-10% of women with PID develop the most severe form, tubo-ovarian abscess. Women with this condition tend to be older (in their thirties and forties) and they also suffer severe pain and probably nausea, vomiting and abdominal distension.

Although, apart from untreated sexually transmitted diseases, tubo-ovarian abscess can also arise due to some other factors and these include:

- Post pelvic surgery
- Uterine perforation at the time of D&C or any vaginal procedure
- Bowel perforation following ruptured appendicitis
- Bowel perforation following diverticulitis
- Pelvic malignancy

Pelvic inflammation disease that has degenerated into abscess cavities is usually treated initially with a broad spectrum antibiotic. The abscess is usually seen as a mixed infection, because, though, the initial infection is often from a STD bacteria, multiple different bacteria from the bowel tract may become involved in the abscess due to transmigration across swollen, inflamed bowel walls surrounding the abscess area. Usually, at least two to three different antibiotics are required immediately diagnosis is made. If the infection doesn't improve, usually within 72hours, then some sort of surgical drainage of the abscess is required. If all these fail, then as a last resort, exploratory surgery removing all of the infected tissue is carried out.