Oophorectomy (Pronunciation: ??'??-f??-r??k't??-m??; from the Greek ??????????????? oophoros "egg-bearing" + ?????????????? ektomia "a cutting out of") is the surgical removal of an ovary or ovaries. The surgery is also called ovariectomy , but this term has been traditionally used in basic science research describing the surgical removal of ovaries in laboratory animals. Removal of the ovaries in women is the biological equivalent of castration in males; however, the term castration is only occasionally used in the medical literature to refer to oophorectomy in humans. In the veterinary sciences, the complete removal of the ovaries, oviducts, uterine horns, and the uterus is called spaying and is a form of sterilization .

In humans, oophorectomy is most often performed due to diseases such as ovarian cysts or cancer; as prophylaxis to reduce the chances of developing ovarian cancer or breast cancer; or in conjunction with removal of the uterus .

The removal of an ovary together with the fallopian tube is called salpingo-oophorectomy or unilateral salpingo-oophorectomy ( USO ). When both ovaries and both Fallopian tubes are removed, the term bilateral salpingo-oophorectomy ( BSO ) is used. Oophorectomy and salpingo-oophorectomy are not common forms of birth control in humans; more usual is tubal ligation, in which the Fallopian tubes are blocked but the ovaries remain intact. In many cases, surgical removal of the ovaries is performed concurrently with a hysterectomy. The formal medical name for removal of a woman's entire reproductive system (ovaries, Fallopian tubes, uterus) is "Total Abdominal Hysterectomy with Bilateral Salpingo-Oophorectomy (TAH-BSO); the more casual term for such a surgery is "ovariohysterectomy". The term " hysterectomy" is often used to refer to removal of any part of the female reproductive system, including just the ovaries; however, the correct definition of " hysterectomy" is removal of the uterus (from the Greek ????????????? hystera "womb" and ?????????????? ektomia "a cutting out of") without removal of the ovaries or Fallopian tubes.

When performed alone (without hysterectomy), an oophorectomy is generally performed by abdominal laparotomy or laparoscopy.

According to the Center for Disease Control, 454,000 women in the United States underwent this type of operation in 2004.

Most bilateral oophorectomies (63%) are performed prophylactically without any medical indication at the same time as hysterectomy (87%). Conversely, unilateral oophorectomy is commonly performed for a medical indication (73%; cyst, endometriosis, benign tumor, inflammation, etc.) and less commonly in conjunction with hysterectomy (61%).

Prophylactic bilateral oophorectomy has been traditionally done in the belief that the benefit of preventing ovarian cancer outweighs the risks associated with removal of ovaries. However, more recent data suggest the balance of risks and benefits is more complicated and that prophylactic oophorectomy without a medical indication decreases long term survival rates substantially. In addition, women with a familial history of ovarian cancer and/or with genetic polymorphisms such as BRCA1/BRCA2 must also weigh those factors into their decision to undergo prophylactic bilateral oophorectomy.

Cancer prevention

For carriers of high risk BRCA1 mutations, prophylactic oophorectomy around age 40 reduces the risk of ovarian and breast cancer and provides significant and substantial long-term survival advantage. Earlier intervention does not, on average, provide any additional benefit but increases risks and adverse effects. For carriers of high risk BRCA2 mutations, oophorectomy around age 40 has only marginal effect on survival; the positive effect of reduced breast and ovarian cancer risk is nearly balanced by adverse effects. The survival advantage is more substantial when oophorectomy is performed together with prophylactic mastectomy.

Reduced problems of endometriosis

In rare cases, oophorectomy can be used to treat endometriosis. This is done to remove a source of hormones that fuel uterine lining growth, thus reducing the overgrowth responsible for endometriosis. Oophorectomy for endometriosis is usually a last-resort surgery due to the risks associated with a sudden cessation of hormone production, most notably early-onset osteoporosis. For this reason, hormonal agonists such as Lupron are usually prescribed first to alter the hormonal cycle prior to proceeding directly to a non-reversible surgical intervention. Oophorectomy for endometriosis is often done in conjunction with a hysterectomy as a final shot at removing all traces of endometriosis in cases where non-surgical treatments such as hormonal agonists have failed to stop the uterine overgrowth.

Ovarian cyst removal without oophorectomy or through partial oophorectomy is often used to treat milder cases of endometriosis when non-surgical hormonal treatments fail to stop cyst formation, or to treat extreme pelvic pain from chronic hormonal-related pelvic problems.

Oophorectomy is a minor surgery and serious complications stemming directly from the surgery are rare. Despite this it has very serious long term consequences stemming mostly from the hormonal effects of the surgery and extending well beyond menopause. The reported risks and adverse effects range from premature death and decline in sexual function. Hormone replacement therapy does not always improve the adverse effects.

Mortality

Oophorectomy is associated with significantly increased all-cause long-term mortality except when performed for cancer prevention in carriers of high risk BRCA mutations. This is particularly pronounced for women who undergo oophorectomy before age 45.

Removal of ovaries causes hormonal changes and symptoms similar to, but generally more severe than, menopause. Women who have had an oophorectomy are usually encouraged to take hormone replacement drugs to prevent other conditions often associated with menopause. Women younger than 45 who have had their ovaries removed face a mortality risk 170% higher than women who have retained their ovaries.. Retaining the ovaries when a hysterectomy is performed is associated with better long term survival.. Hormone therapy for women with oophorectomies performed before age 45 improves the long term outcome and all cause mortality rates.

Women who have had bilateral oophorectomy surgeries lose most of their ability to produce the hormones estrogen and progesterone, and lose about half of their ability to produce testosterone, and subsequently enter what is known as " surgical menopause " (as opposed to normal menopause, which occurs naturally in women as part of the aging process). "Surgical menopause" differs from naturally occurring menopause in several respects: Surgical menopause is the result of surgery, while menopause is a natural event. A menopausal woman has intact functional female organs, a woman with surgical menopause does not. In natural menopause the ovaries generally continue to produce low levels of hormones, while in surgical menopause the ovaries and their hormones are absent, which can explain why surgical menopause is generally accompanied by a more sudden and severe onset of symptoms than natural menopause, symptoms which may continue until natural age of menopause arrives. These symptoms are commonly addressed through hormone therapy, utilizing various forms of estrogen, testosterone, progesterone or a combination of them.

Cardiovascular risk

When the ovaries are removed a woman is at a seven times greater risk of cardiovascular disease, but the mechanisms are not precisely known. The hormone production of the ovaries currently cannot be sufficiently mimicked by drug therapy. The ovaries produce hormones a woman needs throughout her entire life, in the quantity they are needed, at the time they are needed, and released directly into the blood stream in a continuous fashion, in response to and as part of the complex endocrine system.

Osteoporosis

Oophorectomy is associated with an increased risk of osteoporosis and bone fractures.

 However, the risk is limited to oophorectomy performed before menopause or during the early perimenopause.  Reduced levels of testosterone in women is predictive of height loss, which may occur as a result of reduced bone density.  In women under the age of 50 who have undergone oophorectomy, 
hormone replacement therapy
 (HRT) is often used to offset the negative effects of sudden hormonal loss (e.g., 
early-onset osteoporosis
) as well as menopausal problems like 
hot flushes (also called "hot flashes") that are usually more severe than those experienced by women undergoing natural menopause.

Adverse effect on sexuality

Oophorectomy significantly impairs sexual well-being. Substantially more women reported libido loss, difficulty with sexual arousal, and vaginal dryness and hormone replacement therapy was not found to improve these symptoms. In addition, testosterone levels in women are associated with a greater sense of sexual desire, and oophorectomy greatly reduces testosterone levels..

Non-hormonal treatments

The side effects of oophorectomy may be alleviated by medicines other than hormonal replacement. Non-hormonal biphosphonates (such as Fosamax and Actonel) increase bone strength and are available as once-a-week pills. Low-dose Selective Serotonin Reuptake Inhibitors (e.g. Paxil, Prozac) alleviate vasomotor menopausal symptoms, i.e. "hot flashes".

Hormonal treatments

In general, hormone replacement therapy is somewhat controversial due to the known carcinogenic and coagulative properties of estrogen; however, many physicians and patients feel the benefits outweigh the risks in women who may face serious health and quality of life issues as a consequence of early surgical menopause. The ovarian hormones estrogen, progesterone, and testosterone are involved in the regulation of hundreds of bodily functions; it is believed by some doctors that hormone therapy programs mitigate surgical menopause side effects such as increased risk of cardiovascular disease, and female sexual dysfunction.

Short-term hormone replacement with estrogen, in high-risk BRCA mutation carriers, was not shown to increase the risk of breast cancer in women who are post-oophorectomic. The results were published in JCO in 2004 and the conclusions were based on a computerized simulation using models of risk and benefit, a lower level of data than a randomized trial per se. This result can probably be generalized to other women at high risk in whom short term (i.e., one- or two-year) treatment with estrogen for hot flashes, may be acceptable.

• Spaying and neutering

• Ovarian Cysts

• Tubal ligation

• Birth control

• Hysterectomy

• Hormone Replacement Therapy

• Castration or orchidectomy - the male equivalent

• Useful list of currently available hormone replacements in the US

• Useful list of currently available hormone replacements in the UK

• A Survivor's Guide to Surgical Menopause : Collected information on managing post-surgical menopause conditions

• Encyclopedia of Surgery Article on Hysterectomy