Ectopic pregnancies are relatively common, accounting for 1.3–2% of all reported pregnancies in the USA. This represents a fourfold increase since 1948 when the reported incidence of ectopic pregnancy was only 0.4%. Suggested reasons for continued increases include the greater presence of risk factors in the general population, improvements in diagnostic methods, and the delay in childbearing until later reproductive life, at which time ectopic pregnancy rates are increased.

Seventy-five percent of deaths in the first trimester and 9–13% of all pregnancy-related deaths in the first trimester are associated with extrauterine pregnancies. However, the mortality rates are on the decline. The case–fatality rate is now approximately 3.8 deaths per 10,000 cases of ectopic pregnancies, a decline of 90% from the 35.5 death per 10,000 reported in 1970.

Identifying risk factors can lead to early diagnosis, allowing for conservative management. A previous history of salpingitis, previous or current sexually transmitted disease, infertility, tubal surgery (including tubal ligation), a history of ectopic pregnancy, past abdominal surgery, and in utero exposure to diethylstilbestrol are risk factors. Others include advanced maternal age, progestin-only contraceptives, postcoital estrogen contraceptives, progesterone-containing intrauterine devices, ovarian hyperstimulation, smoking, and prior in vitro fertilization and embryo transfer.

One-third of ectopic pregnancies are associated with tubal damage due to surgery or infection, while another one-third is seen with smoking. Women who have undergone assisted reproduction have a risk for an extrauterine pregnancy twice that of women who spontaneously conceive.

Women who experience failure of their method of contraception (especially progestin-only oral contraceptives, progestin-only implants, an IUD or permanent surgical sterilization) should be evaluated for an ectopic pregnancy. These methods of contraception reduce the overall rate of ectopic pregnancy because they reduce the rate of all pregnancies. However, the pregnancies that do occur are often implanted outside the uterus.

The clinical presentation of ectopic pregnancy ranges from asymptomatic to acutely ill. About 50% of patients present with abdominal pain, usually localized to the affected side, and vaginal bleeding after a late or missed period. To complicate the diagnosis, one-third of patients may have no signs or symptoms. Generally, in the early part of the disease course, patients are asymptomatic except possibly for symptoms of pregnancy. As time progresses, symptoms of unilateral pain, vaginal spotting or bleeding generally begin. In the more advanced stages, patients may exhibit syncopal episodes, dizziness, severe pain, orthostatic changes, tachycardia, shock, and/or a distended, rigid abdomen. The ectopic pregnancy generally causes at most a slight temperature elevation or a slight rise in the white blood cells.