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

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.

Approximately 20% of female infertility can be attributed to tubal causes. Distal tubal occlusion (affecting the end towards the ovary) is typically associated with hydrosalpinx formation and often caused by "Chlamydia trachomatis". Pelvic adhesions may be associated with such an infection. In less severe forms, the fimbriae may be aggluntinated and damaged, but some patency may still be preserved. Midsegment tubal obstruction can be due to tubal ligation procedures as that part of the tube is a common target of sterilization interventions. Proximal tubal occlusion can occur after infection such as a septic abortion. Also, some tubal sterilization procedures such as the Essure procedure target the part of the tube that is near the uterus..

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.

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.

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.

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.

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.

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.

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.

Tubal factor infertility (TFI) is female infertility caused by diseases, obstructions, damage, scarring, congenital malformations or other factors which impede the descent of a fertilized or unfertilized ovum into the uterus through the Fallopian tubes and prevents a normal pregnancy and full term birth. Tubal factors cause 25-30% of infertility cases. Tubal factor is one complication of Chlamydia trachomatis infection in women.

Sexually transmitted Chlamydia and genital mycoplasma infections are preventable causes of infertility and negative pregnancy outcomes. When the infections progress and ascend, they can result in TFI. Infertility can have multiple possible causes and may not be recognized for years after a gonorrhea, Chlamydia or Mycoplasma infection has caused tubal damage, as the affected woman may not have attempted to become pregnant until years later.

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.

Tubal factor infertility can be due to Chlamydia infection and testing for Chlamydia antibodies is one diagnostic tool. Women have difficulty getting pregnant or carrying a baby to term due to the buildup of scar tissue in the Fallopian tubes causing damage to the cilia on the epithelial cells. TFI can also be due to endometriosis.

Women with the condition may be asymptomatic and unaware of having a uniconuate uterus; normal pregnancy may occur. In a review of the literature Reichman et al. analyzed the data on pregnancy outcome of 290 women with a unicornuate uterus. 175 women had conceived for a total of 468 pregnancies. They found that about 50% of patients delivered a live baby. The rates for ectopic pregnancy was 2.7%, for miscarriage 34%, and for preterm delivery 20%, while the intrauterine demise rate was 10%. Thus patients with a unicornuate uterus are at a higher risk for pregnancy loss and obstetrical complications.

The epidemiology of TOA is closely related to that of pelvic inflammatory disease which is estimated to one million people yearly.

Patients with a unicornuate uterus may need special attention during pregnancy as pregnancy loss, fetal demise, premature birth, and malpresentation are more common. It is unproven that cerclage procedures are helpful.

A pregnancy in a rudimentary horn cannot be saved and needs to be removed with the horn to prevent a potentially fatal rupture of the horn and uterus.

Although it is unclear whether interventions before conception or early in pregnancy such as resection of the rudimentary horn and prophylactic cervical cerclage decidedly improve obstetrical outcomes, current practice suggests that such interventions may be helpful.

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.

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%.

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.

Factors that can cause male as well as female infertility are:

- DNA damage

- DNA damage reduces fertility in female ovocytes, as caused by smoking, other xenobiotic DNA damaging agents (such as radiation or chemotherapy) or accumulation of the oxidative DNA damage 8-hydroxy-deoxyguanosine

- DNA damage reduces fertility in male sperm, as caused by oxidative DNA damage, smoking, other xenobiotic DNA damaging agents (such as drugs or chemotherapy) or other DNA damaging agents including reactive oxygen species, fever or high testicular temperature

- General factors

- Diabetes mellitus, thyroid disorders, undiagnosed and untreated coeliac disease, adrenal disease

- Hypothalamic-pituitary factors

- Hyperprolactinemia

- Hypopituitarism

- The presence of anti-thyroid antibodies is associated with an increased risk of unexplained subfertility with an odds ratio of 1.5 and 95% confidence interval of 1.1–2.0.

- Environmental factors

- Toxins such as glues, volatile organic solvents or silicones, physical agents, chemical dusts, and pesticides. Tobacco smokers are 60% more likely to be infertile than non-smokers.

German scientists have reported that a virus called Adeno-associated virus might have a role in male infertility, though it is otherwise not harmful. Other diseases such as chlamydia, and gonorrhea can also cause infertility, due to internal scarring (fallopian tube obstruction).

Patients with an ectopic pregnancy are generally at higher risk for a recurrence, however, there are no specific data for patients with an interstitial pregnancy. When a new pregnancy is diagnosed it is important to monitor the pregnancy by transvaginal sonography to assure that is it properly located, and that the surgically repaired area remains intact. Cesarean delivery is recommended to avoid uterine rupture during labor.

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.

In the US, up to 25% of infertile couples have unexplained infertility.

In the US, up to 20% of infertile couples have unexplained infertility. In these cases abnormalities are likely to be present but not detected by current methods. Possible problems could be that the egg is not released at the optimum time for fertilization, that it may not enter the fallopian tube, sperm may not be able to reach the egg, fertilization may fail to occur, transport of the zygote may be disturbed, or implantation fails. It is increasingly recognized that egg quality is of critical importance and women of advanced maternal age have eggs of reduced capacity for normal and successful fertilization. Also, polymorphisms in folate pathway genes could be one reason for fertility complications in some women with unexplained infertility. However, a growing body of evidence suggests that epigenetic modifications in sperm may be partially responsible.