Causes
Numerous medical conditions can contribute to infertility. In fact, most cases of infertility are due to other medical conditions. These disorders can damage the fallopian tubes, interfere with ovulation, or cause hormonal complications.
Some of the main medical conditions associated with infertility follow.
Pelvic Inflammatory Disease
Pelvic inflammatory disease (PID) is a major cause of female infertility worldwide. PID comprises a variety of infections caused by different bacteria that affect the reproductive organs, appendix, and parts of the intestine that lie in the pelvic area. The sites of infection most often implicated in infertility are in the fallopian tubes, a specific condition referred to as salpingitis.
Causes of PID. PID may result from many different conditions that cause infections. Among them are:
- Sexually transmitted diseases (cause of most PID). Chlamydia trachomatis is an infectious organism that causes 75% of infertility in the fallopian tubes. Gonorrhea is responsible for most of the remaining cases.
- Pelvic tuberculosis
- Nonsterile abortions
- Ruptured appendix
Effects of PID. Severe or frequent attacks of PID can eventually cause scarring, abscess formation, and tubal damage that result in infertility. About 20% of women who develop symptomatic PID become infertile. PID also significantly increases the risk of ectopic pregnancy (fertilization in the fallopian tubes). The severity of the infection, not the number of the infections, appears to pose the greater risk for infertility.
Endometriosis
Endometriosis may account for as many as 30% of infertility cases. Endometriosis rarely causes an absolute inability to conceive, but, nevertheless, it can contribute to it both directly and indirectly.
Endometriosis is a noncancerous condition in which cells that normally line the uterus (endometrium) also grow on other areas of the body, causing pain and irregular bleeding.
Endometrial cysts may cause infertility in several ways:
- If implants occur in the fallopian tubes, they may block the egg's passage.
- Implants that occur in the ovaries prevent the release of the egg.
- Severe endometriosis can eventually form rigid webs of scar tissue (adhesions) between the uterus, ovaries, and fallopian tubes, thereby preventing the transfer of the egg to the tube.
[For more information, see In-Depth Report #74: Endometriosis.]
Polycystic Ovarian Syndrome
Polycystic ovarian syndrome (PCOS) is a condition in which the ovaries produce high amounts of androgens (male hormones), particularly testosterone. PCOS occurs in about 6% of women, and amenorrhea or oligomenorrhea (infrequent menses) is quite common.
Click the icon to see an image of polycystic ovarian syndrome.
In PCOS, increased androgen production produces high luteinizing hormone (LH) levels and low follicle-stimulating hormone (FSH) levels, so that follicles are prevented from producing a mature egg. Without egg production, the follicles swell with fluid and form into cysts. Every time an egg is trapped within the follicle, another cyst forms and the ovary swells, sometimes reaching the size of a grapefruit. Without ovulation, progesterone is no longer produced, whereas estrogen levels remain normal.
