Ovarian torsion accounts for about 3% of gynecologic emergencies. The incidence of ovarian torsion among women of all ages is 5.9 per 100,000 women, and the incidence among women of reproductive age (15–45 years) is 9.9 per 100,000 women. In 70% of cases, it is diagnosed in women between 20 and 39 years of age. The risk is greater during pregnancy and in menopause. Risk factors include increased length of the ovarian ligaments, pathologically enlarged ovaries (more than 6 cm), ovarian masses or cysts, and enlarged corpus luteum in pregnancy.

The prognosis is determined primarily by the cancer stage. Most tumours are discovered at an early stage and have a good prognosis, especially when compared to uterine carcinosarcoma. Five year survival for stage I and stage III tumours is approximately 80% and 50% respectively.

Ovarian pregnancies are rare: the vast majority of ectopic pregnancies occur in the fallopian tube; only about 0.15-3% of ectopics occur in the ovary. The incidence has been reported to be about 1:3,000 to 1:7,000 deliveries.

True cervical pregnancies tend to abort; if, however, the pregnancy is located higher in the canal and the placenta finds support in the uterine cavity it can go past the first trimester. With the placenta being implanted abnormally extensive vaginal bleeding can be expected at time of delivery and placental removal. While early cervical pregnancies may abort spontaneously or can be managed with excision, D&C, suturing, electrocautery, and tamponading, by medication such as methotrexate, and/or by uterine artery embolization, a more advanced pregnancy may require a hysterectomy to control bleeding. The more advanced the pregnancy the higher the risk for a major bleeding necessitating a hysterectomy.

On a very rare occasion, a cervical pregnancy results in the birth of a live baby, typically the pregnancy is in the upper part of the cervical canal and manages to extend into the lower part of the uterine cavity.

A cervical pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as to not to endanger the intrauterine pregnancy.

Most women of reproductive age develop small cysts each month, and large cysts that cause problems occur in about 8% of women before menopause. Ovarian cysts are present in about 16% of women after menopause and if present are more likely to be cancer.

Benign ovarian cysts are common in asymptomatic premenarchal girls and found in approximately 68% of ovaries of girls 2–12 years old and in 84% of ovaries of girls 0–2 years old. Most of them are smaller than 9 mm while about 10-20% are larger macrocysts. While the smaller cysts mostly disappear within 6 months the larger ones appear to be more persistent.

Uterine adenosarcomas are typically treated with a total abdominal hysterectomy and bilateral salpingoophorectomy (TAH-BSO). Ovary sparing surgery may be done in women wishing to preserve fertility.

The prevalence of heterotopic pregnancy is estimated at 0.6‑2.5:10,000 pregnancies. There is a significant increase in the incidence of heterotopic pregnancy in women undergoing ovulation induction. An even greater incidence of heterotopic pregnancy is reported in pregnancies following assisted reproduction techniques such as In Vitro Fertilization (IVF) and Gamete intrafallopian transfer (GIFT), with an estimated incidence at between 1 and 3 in 100 pregnancies. If there is embryo transfer of more than 4 embryos, the risk has been quoted as 1 in 45. In natural conceptions, the incidence of heterotopic pregnancy has been estimated to be 1 in 30 000 pregnancies.

Ovarian pregnancies are dangerous and prone to internal bleeding. Thus, when suspected, intervention is called for.

Traditionally, an explorative laparotomy was performed, and once the ovarian pregnancy was identified, an oophorectomy or salpingo-oophorectomy was performed, including the removal of the pregnancy. Today, the surgery can often be performed via laparoscopy. The extent of surgery varies according to the amount of tissue destruction that has

occurred. Patients with an ovarian pregnancy have a good prognosis for future fertility and therefore conservative surgical management is advocated. Further, in attempts to preserve ovarian tissue, surgery may involve just the removal of the pregnancy with only a part of the ovary. This can be accomplished by an ovarian wedge resection.

Ovarian pregnancies have been successfully treated with methotrexate since it was introduced in the management of ectopic pregnancy in 1988.

An ovarian pregnancy can develop together with a normal intrauterine pregnancy; such a heterotopic pregnancy will call for expert management as not to endanger the intrauterine pregnancy.

Surgical treatment of ovarian torsion includes laparoscopy to uncoil the torsed ovary and possibly oophoropexy to fixate the ovary which is likely to twist again. In severe cases, where blood flow is cut off to the ovary for an extended period of time, necrosis of the ovary can occur. In these cases the ovary must be surgically removed.

The fertility drug clomiphene citrate (Clomid, Serophene), used to induce ovulation, increases the risk of a corpus luteum cyst developing after ovulation. These cysts don't prevent or threaten a resulting pregnancy. Women on birth control pills usually do not form these cysts; in fact, preventing these cysts is one way birth control pills work.

In contrast, the progesterone-only pill can cause increased frequency of these cysts.

The incidence has been reported to be about 1:1,000 to 1: 16,000 pregnancies.

Pregnancies involving the isthmus - the segment of the uterus between the cervix and the fundus - are more common than true cervical pregnancies. While in many situations the cause of the abnormal implantation remains unclear, there is evidence to link the development of cervical pregnancy to uterine instrumentation, specifically repeated D&Cs (dilatation and curettage). Cervical pregnancies are to be distinguished from pregnancies that start from an implantation in a scar of a previous cesarean section, so-called "scar pregnancies".

Although most cases of ovarian cysts involve monitoring, some cases require surgery. This may involve removing the cyst, or one or both ovaries. Technique is typically laparoscopic, unless the cyst is particularly large, or if pre-operative imaging suggests malignancy or complex anatomy. In certain situations, the cyst is entirely removed, while with cysts with low recurrence risk, younger patients, or which are in anatomically eloquent areas of the pelvis, they can be drained. Features that may indicate the need for surgery include:

- Persistent complex ovarian cysts

- Persistent cysts that are causing symptoms

- Complex ovarian cysts larger than 5 cm

- Simple ovarian cysts larger 10 cm or larger than 5 cm in postmenopausal patients

- Women who are menopausal or perimenopausal

Extrauterine pregnancies are non-viable and can be fatal to the mother if left untreated. The mortality rate for the extrauterine pregnancy is approximately 35%.

A Corpus luteum cyst is a type of ovarian cyst which may rupture about the time of menstruation, and take up to three months to disappear entirely. A corpus luteum cyst rarely occurs at age 50+, because eggs are no longer being released in menopausal women. Corpus luteum cysts may contain blood and other fluids. The physical shape of a corpus luteum cyst may appear as an enlargement of the ovary itself, rather than a distinct mass -like growth on the surface of the ovary.

An adnexal mass is a lump in tissue of the adnexa of uterus (structures closely related structurally and functionally to the uterus such as the ovaries, fallopian tubes, or any of the surrounding connective tissue). Adnexal masses can be benign or cancerous, and they can be categorized as simple or complex. One of the most important factors used to determine the clinical suspicion of malignancy of an adnexal mass is the sonographic appearance of the mass. Indications that the mass is at a higher risk of being malignant include: presence of loculations, nodules, papillary structures, septations, size greater than 10 cm.

In premenopausal women, adnexal masses include ovarian cysts, ectopic (tubal) pregnancies, benign (noncancerous) or malignant (cancerous) tumors, endometriomas, polycystic ovaries, and tubo-ovarian abscess. In females of reproductive age, adnexal masses can be physiologic or complex masses. Most common causes for adnexal masses in premenopausal women are follicular cysts and corpus luteum cysts. Abscesses can form as a complication of pelvic inflammatory disease.

Other masses include endometriomas, polycystic ovaries, and benign neoplasms.

In postmenopausal women, adnexal masses may be caused by cancer, fibroids, fibromas, diverticular abscess.

In the ovaries of sexually mature women, follicles grow, and oocyte matures in them, to prepare for potential fertilization. As a menstrual cycle progresses, a dominant follicle begins to stand out, and in the middle of the menstrual cycle it reaches its maximum size of about 20mm. Then the follicle ruptures, releasing a mature egg (ovulation). The location from which the follicle emerges then forms a temporary cyst, called the corpus luteum, which produces hormones to continue the menstrual cycle and mature the uterine lining. This is the normal ovarian cycle.

In cases of dystrophic and sclerotic changes in ovarian tissue, acute and chronic inflammatory processes in the uterus, or in polycystic ovary syndrome and some other diseases, as well as the result of medication that stimulate ovulation, certain irregularities in ovulation process and corpus luteum formation occur. As a result, blood vessels in the ovary contract, become dilated, and increase intra-ovarian bleeding. As a result, a hemorrhage can occur in the corpus luteum due to the fragility of blood vessels, causing a hematoma. All this is accompanied by pain, weakness, dizziness, nausea, vomiting, pale skin, and/or fainting. If left untreated, internal bleeding may increase, creating a real threat to the health and life of the woman. Other possible causes of ovarian rupture include abdominal trauma, excessive physical stress, vigorous sexual intercourse, horseback riding, etc.

Treatment depends on the type of ovary apoplexy and the severity of intra-abdominal bleeding, but the condition must be treated in a hospital. In the case of pain without signs of intraabdominal bleeding, conservative therapy may be initiated, which includes bed rest, antispasmodics, and physiotherapy. In the presence or suspected internal bleeding, surgery is indicated via laparoscopy or laparotomy. Other treatments may include efforts to stop the bleeding or resection of the affected portion of the ovary. However, in cases in which there is extensive damage to the ovary, it may be necessary to remove it.

After being discharged from the hospital, it is important to take steps to prevent a recurrence in the future. Such steps include avoiding risk factors or beginning a regimen of oral contraceptives to control ovarian activity.

10% of cases occur in women who are ovulating, but progesterone secretion is prolonged because estrogen levels are low. This causes irregular shedding of the uterine lining and break-through bleeding. Some evidence has associated Ovulatory DUB with more fragile blood vessels in the uterus.

It may represent a possible endocrine dysfunction, resulting in menorrhagia or metrorrhagia.

Mid-cycle bleeding may indicate a transient estrogen decline, while late-cycle bleeding may indicate progesterone deficiency.

Dysfunctional uterine bleeding (DUB) is abnormal genital tract bleeding based in the uterus and found in the absence of demonstrable structural or organic disease. It is usually due to hormonal disturbances: reduced levels of progesterone cause low levels of prostaglandin F2alpha and cause menorrhagia (abnormally heavy flow); increased levels of tissue plasminogen activator (TPA) (a fibrinolytic enzyme) lead to more fibrinolysis.

Diagnosis must be made by exclusion, since organic pathology must first be ruled out.

DUB can be classified as "ovulatory" or "anovulatory", depending on whether ovulation is occurring or not. It is usually a menstrual disorder, although abnormal bleeding from the uterus is possible outside menstruation.

Some sources state that the term "dysfunctional" implies a hormonal mechanism. Use of the term "abnormal uterine bleeding" is preferred in today's medicine.

There are various explanations, none of which is universally accepted because of the complex involvement of cortical, hypothalamic, endocrine, and psychogenic factors. Proposed mechanisms include the effect of stress on the hypothalamo-pituitary-adrenal axis, constipation, weight gain, and the movement of intestinal gas.

Dogs become pseudopregnant following an estrus phase in which the female dog is not bred, or in which she is bred by an infertile male. Most species require signals from an embryo (such as IFN-τ in ruminants) to alert the female's body of a pregnancy. This maternal recognition of pregnancy will cause persistence of the corpus luteum and the development of characteristics and behaviors necessary to care for offspring. Limited research suggests that progesterone secretion is similar in pregnant and non-pregnant female dog, so veterinary researchers hypothesize that they may not require molecular factors from the embryo for maternal recognition of pregnancy, and instead the corpus luteum persists regardless of pregnancy. Since the corpus luteum is not degraded, it will cause the development of maternal characteristics in the absence of pregnancy. Pseudopregnant dogs will develop their mammary glands, lactate, and build nests to varying degrees depending on breed. Although female dogs usually only cycle once or twice per year, pseudopregnancy is common.

A malignant mixed Müllerian tumor, also known as malignant mixed mesodermal tumor, MMMT and carcinosarcoma, is a malignant neoplasm found in the uterus, the ovaries, the fallopian tubes and other parts of the body that contains both carcinomatous (epithelial tissue) and sarcomatous (connective tissue) components. It is divided into two types, homologous (in which the sarcomatous component is made of tissues found in the uterus such as endometrial, fibrous and/or smooth muscle tissues) and a heterologous type (made up of tissues not found in the uterus, such as cartilage, skeletal muscle and/or bone). MMMT account for between two and five percent of all tumors derived from the body of the uterus, and are found predominantly in postmenopausal women with an average age of 66 years. Risk factors are similar to those of adenocarcinomas and include obesity, exogenous estrogen therapies, and nulliparity. Less well-understood but potential risk factors include tamoxifen therapy and pelvic irradiation.

There is debate over the naming of MMMT; the term carcinosarcoma was formerly used to describe lesions with homologous tumors, and "malignant mixed Müllerian tumor" or "mixed mesodermal tumor" was used to describe heterologous tumors. While "carcinosarcoma" now considered standard, "malignant mixed Müllerian tumor" has a lengthy history within gynecological literature and is expected to continue to be used. The naming issue to a certain extent reflects histological characteristics and development of the tumors, in which the different types of tissues are believed to either develop separately and join into a single mass (the "collision" theory), that an adenocarcinoma stimulates the stroma to create a tumor (the "composition" theory), or that the tumor is the result of a stem cell that differentiates into different cell types (the "combination" theory). "Collision" tumors are normally easily recognized and not considered true MMMTs; the "combination" theory is most widely held, and is due to evidence that the tumors develop from a single line of cells, developing in a fashion similar to the fundus of the uterus from the Müllerian duct - first from a stem cell into a population of cells, that then differentiates into epithelial and stromal components.

There is evidence that some tumors are better explained by the composition theory, due to the aggressive nature of the epithelial cells involved which tend to metastasize much more readily than the sarcomal component. The behavior of MMMT overall is more related to the type and grade of the epithelium than the sarcoma, which suggests the sarcomal portion is an atypical "bystander" than primary driver of the tumor. Despite this, when purely endometrial tumors are compared to MMMTs, the MMMT tumor tends to have a worse prognosis.

A 2006 review stated that RS often leads renal cancer between ages 30-50. Renal cancer kills about 1 in 3 people, but 5-year survival rates improved between 1974-1976 and 1995-2000, from 52% to 64%.