The cause is not entirely clear. Risk factors include having a family history of the condition.

Some factors associated with endometriosis include:

- not having had yet given birth

- prolonged exposure to estrogen - for example, in late menopause or early menarche

- obstruction of menstrual outflow - for example, in Müllerian anomalies

Several studies have investigated the potential link between exposure to dioxins and endometriosis, but the evidence is equivocal and potential mechanisms are poorly understood. A 2004 review of studies of dioxin and endometriosis concluded that "the human data supporting the dioxin-endometriosis association are scanty and conflicting", and a 2009 follow-up review also found that there was "insufficient evidence" in support of a link between dioxin exposure and women developing endometriosis. A 2008 review concluded that more work was needed, stating that "although preliminary work suggests a potential involvement of exposure to dioxins in the pathogenesis of endometriosis, much work remains to clearly define cause and effect and to understand the potential mechanism of toxicity".

AS has a reported incidence of 25% of D&Cs performed 1–4 weeks post-partum, up to 30.9% of D&Cs performed for missed miscarriages and 6.4% of D&Cs performed for incomplete miscarriages. In another study, 40% of patients who underwent repeated D&C for retained products of conception after missed miscarriage or retained placenta developed AS.

In the case of missed miscarriages, the time period between fetal demise and curettage may increase the likelihood of adhesion formation due to fibroblastic activity of the remaining tissue.

The risk of AS also increases with the number of procedures: one study estimated the risk to be 16% after one D&C and 32% after 3 or more D&Cs. However, a single curettage often underlies the condition.

In an attempts to estimate the prevalence of AS in the general population, it was found in 1.5% of women undergoing hysterosalpingography HSG, and between 5 and 39% of women with recurrent miscarriage.

After miscarriage, a review estimated the prevalence of AS to be approximately 20% (95% confidence interval: 13% to 28%).

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.

The extent of adhesion formation is critical. Mild to moderate adhesions can usually be treated with success. Extensive obliteration of the uterine cavity or fallopian tube openings (ostia) and deep endometrial or myometrial trauma may require several surgical interventions and/or hormone therapy or even be uncorrectable. If the uterine cavity is adhesion free but the ostia remain obliterated, IVF remains an option. If the uterus has been irreparably damaged, surrogacy or adoption may be the only options.

Depending on the degree of severity, AS may result in infertility, repeated miscarriages, pain from trapped blood, and future obstetric complications If left untreated, the obstruction of menstrual flow resulting from adhesions can lead to endometriosis in some cases.

Patients who carry a pregnancy even after treatment of IUA may have an increased risk of having abnormal placentation including placenta accreta where the placenta invades the uterus more deeply, leading to complications in placental separation after delivery. Premature delivery, second-trimester pregnancy loss, and uterine rupture are other reported complications. They may also develop incompetent cervix where the cervix can no longer support the growing weight of the fetus, the pressure causes the placenta to rupture and the mother goes into premature labour. Cerclage is a surgical stitch which helps support the cervix if needed.

Pregnancy and live birth rate has been reported to be related to the initial severity of the adhesions with 93, 78, and 57% pregnancies achieved after treatment of mild, moderate and severe adhesions, respectively and resulting in 81, 66, and 32% live birth rates, respectively. The overall pregnancy rate after adhesiolysis was 60% and the live birth rate was 38.9% according to one study.

Age is another factor contributing to fertility outcomes after treatment of AS. For women under 35 years of age treated for severe adhesions, pregnancy rates were 66.6% compared to 23.5% in women older than 35.

Adenomyosis itself can cause infertility issues, however, fertility can be improved if the adenomyosis has resolved following hormone therapies like levonorgestrel therapy. The discontinuation of medication or removal of IUD can be timed to be coordinated with fertility treatments. There has also been one report of a successful pregnancy and healthy birth following high-frequency ultrasound ablation of adenomyosis.

Preterm labour and premature rupture of membranes both occur more frequently in women with adenomyosis.

In sub-fertile women who received in-vitro fertilization (IVF), women with adenomyosis were less likely to become pregnant and subsequently more likely to experience a miscarriage. Given this, it is encouraged to screen women for adenomyosis by TVUS or MRI before starting assisted reproduction treatments (ART).

Adenomyosis is a benign but often progressing condition. It is advocated that adenomyosis poses no increased risk for cancer development. However, both entities could coexist and the endometrial tissue within the myometrium could harbor endometrioid adenocarcinoma, with potentially deep myometrial invasion. As the condition is estrogen-dependent, menopause presents a natural cure. Ultrasound features of adenomyosis will still be present after menopause. People with adenomyosis are also more likely to have uterine fibroids or endometriosis.

Over one million cases of acute salpingitis are reported every year in the US, but the number of incidents is probably larger, due to incomplete and untimely reporting methods and that many cases are reported first when the illness has gone so far that it has developed chronic complications. For women age 16–25, salpingitis is the most common serious infection. It affects approximately 11% of females of reproductive age.

Salpingitis has a higher incidence among members of lower socioeconomic classes. However, this is thought of being an effect of earlier sex debut, multiple partners, and decreased ability to receive proper health care rather than any independent risk factor for salpingitis.

As an effect of an increased risk due to multiple partners, the prevalence of salpingitis is highest for people age 15–24 years. Decreased awareness of symptoms and less will to use contraceptives are also common in this group, raising the occurrence of salpingitis.

For the affected, 20% need hospitalization.

Regarding patients age 15–44 years, 0.29 per 100,000 dies from salpingitis.

However, salpingitis can also lead to infertility because the eggs released in ovulation can't get contact with the sperm. Approximately 75,000-225,000 cases of infertility in the US are caused by salpingitis. The more times one has the infection, the greater the risk of infertility. With one episode of salpingitis, the risk of infertility is 8-17%. With 3 episodes of salpingitis, the risk is 40-60%, although the exact risk depends on the severity of each episode.

In addition, damaged oviducts increase the risk of ectopic pregnancy. Thus, if one has had salpingitis, the risk of a pregnancy to become ectopic is 7 to 10-fold as large. Half of ectopic pregnancies are due to a salpingitis infection.

Other complications are:

- Infection of ovaries and uterus

- Infection of sex partners

- An abscess on the ovary

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 major cause for distal tubal occlusion is pelvic inflammatory disease (PID), usually as a consequence of an ascending infection by chlamydia or gonorrhea. However, not all pelvic infections will cause distal tubal occlusion. Tubal tuberculosis is an uncommon cause of hydrosalpinx formation.

While the ciliae of the inner lining (endosalpinx) of the fallopian tube beat towards the uterus, tubal fluid is normally discharged via the fimbriated end into the peritoneal cavity from where it is cleared. If the fimbriated end of the tube becomes agglutinated, the resulting obstruction does not allow the tubal fluid to pass; it accumulates and reverts its flow downstream, into the uterus, or production is curtailed by damage to the endosalpinx. This tube then is unable to participate in the reproductive process: sperm cannot pass, the egg is not picked up, and fertilization does not take place.

Other causes of distal tubal occlusion include adhesion formation from surgery, endometriosis, and cancer of the tube, ovary or other surrounding organs.

A hematosalpinx is most commonly associated with an ectopic pregnancy. A pyosalpinx is typically seen in a more acute stage of PID and may be part of a tuboovarian abscess (TOA).

Tubal phimosis refers to a situation where the tubal end is partially occluded, in this case fertility is impeded, and the risk of an ectopic pregnancy is increased.

The incidence of ovarian remnant syndrome is difficult to determine. The available data are limited to case reports or to retrospective case series. The best available data are from a study describing the frequency and outcome of laparoscopy in women with chronic pelvic pain and/or a pelvic mass who were found to have ovarian remnants. In 119 women who underwent hysterectomy and oophorectomy by laparoscopy, ovarian remnants were known in 5 and were found during surgery in 21 patients (18%).[2] However, this was a small study and the participants were only symptomatic women. Therefore, it is not known whether the data can be extrapolated to include all women who have undergone oophorectomy.

Most commonly a tube may be obstructed due to infection such as pelvic inflammatory disease (PID). The rate of tubal infertility has been reported to be 12% after one, 23% after two, and 53% after three episodes of PID. The Fallopian tubes may also be occluded or disabled by endometritis, infections after childbirth and intraabdominal infections including appendicitis and peritonitis. The formation of adhesions may not necessarily block a fallopian tube, but render it dysfunctional by distorting or separating it from the ovary. It has been reported that women with distal tubal occlusion have a higher rate of HIV infection.

Fallopian tubes may be blocked as a method of contraception. In these situations tubes tend to be healthy and typically patients requesting the procedure had children. Tubal ligation is considered a permanent procedure.

Interstitial pregnancies account for 2–4% of all tubal pregnancies, or for 1 in 2,500 to 5,000 live births. About one in fifty women with an interstitial pregnancy dies. Patients with an interstitial pregnancies have a 7-times higher mortality than those with ectopics in general. With the growing use of assisted reproductive technologies, the incidence of interstitial pregnancy is rising.

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.

In vitro fertilisation is a process by which an egg is fertilised by sperm outside the body: "in vitro". IVF is a major treatment for infertility when other methods of assisted reproductive technology have failed. The process involves monitoring a woman's ovulatory process, removing ovum or ova (egg or eggs) from the woman's ovaries and letting sperm fertilise them in a fluid medium in a laboratory. When a woman's natural cycle is monitored to collect a naturally selected ovum (egg) for fertilisation, it is known as natural cycle IVF. The fertilised egg (zygote) is then transferred to the patient's uterus with the intention of establishing a successful pregnancy.

While IVF therapy has largely replaced tubal surgery in the treatment of infertility, the presence of hydrosalpinx is a detriment to IVF success. It has been recommended that prior to IVF, laparoscopic surgery should be done to either block or remove hydrosalpinges.

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.

As pelvic inflammatory disease is the major cause of hydrosalpinx formation, steps to reduce sexually transmitted disease will reduce incidence of hydrosalpinx. Also, as hydrosalpinx is a sequel to a pelvic infection, adequate and early antibiotic treatment of a pelvic infection is called for.

In the United States, uterus didelphys is reported to occur in 0.1–0.5% of women. It is difficult to know the exact occurrence of this anomaly, as it may go undetected in the absence of medical and reproductive complications.

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

A number of twin gestations have occurred where each uterus carried its pregnancy separately. A recent example occurred on February 26, 2009, when Sarah Reinfelder of Sault Ste. Marie, Michigan delivered two healthy, although seven weeks premature, infants by cesarean section at Marquette General Hospital. It is possible that the deliveries occur at different times, thus the delivery interval could be days or even weeks.

There are a number of risk factors for ectopic pregnancies. However, in as many as one third to one half no risk factors can be identified. Risk factors include: pelvic inflammatory disease, infertility, use of an intrauterine device (IUD), previous exposure to DES, tubal surgery, intrauterine surgery (e.g. D&C), smoking, previous ectopic pregnancy, endometriosis, and tubal ligation. A previous induced abortion does not appear to increase the risk.

Prognosis in unexplained infertility depends on many factors, but can roughly be estimated by e.g. the

Hunault model, which takes into account female age, duration of infertility/subfertility, infertility/subfertility being primary or secondary, percentage of motile sperm and being referred by a general practitioner or gynecologist.

The cause of ORS is the unintentional retention of ovarian tissue after the procedure to remove the ovaries. If a woman is receiving hormone replacement therapy, distinguishing from other disease process may be difficult. Other confounding conditions contributing to ORS are thick and profuse pelvic adhesions, inflammation, bleeding after surgery (peri-operative bleeding), and ovaries which are retroperitoneal, can all contribute to the unintentional preservation of ovarian fragments.

Fertility following ectopic pregnancy depends upon several factors, the most important of which is a prior history of infertility. The treatment choice does not play a major role; A randomized study in 2013 concluded that the rates of intrauterine pregnancy 2 years after treatment of ectopic pregnancy are approximately 64% with radical surgery, 67% with medication, and 70% with conservative surgery. In comparison, the cumulative pregnancy rate of women under 40 years of age in the general population over 2 years is over 90%.