Ectopic pregnancy is a major cause of maternal and fetal morbidity. The incidence of ectopic pregnancy is increasing, especially among women older than 35 years.

Tay and associates reviewed the incidence, causes, diagnosis and management of ectopic pregnancy using published evidence as well as clinical experience. The risk of ectopic pregnancy is increased by having had a previous ectopic pregnancy, tubal damage from infection or surgery, a history of infertility, therapy for in vitro fertilization, increased age and smoking. A history of pelvic inflammatory disease is particularly important, especially if the causative agent is Chlamydia trachomatis, as a predictor of ectopic risk.

Ectopic pregnancies usually present after a woman has been amenorrheic for about seven weeks. Abdominal pain is usually lateral, although a small percentage of women report no pain, and about one third of women with ectopic pregnancy lack adnexal tenderness. Because of the ubiquity of the presentation, the diagnosis is difficult, but any sexually active woman presenting with abdominal pain and vaginal bleeding after an interval of amenorrhea has an ectopic pregnancy until proved otherwise (see accompanying table on page 762). The differential diagnosis includes miscarriage, an ovarian accident and pelvic inflammatory disease. Tubal rupture, caused by invasion on the trophoblast, often occurs when prodromal symptoms are overlooked.

Early evaluation is appropriate for suspected ectopic pregnancy. The initial investigations are a sensitive pregnancy test with measurement of serum β human chorionic gonadotropin (hCG) together with abdominal or transvaginal ultrasonography. In the presence of positive ultrasonographic evidence of ectopic pregnancy, a recommended cutoff for diagnosis of ectopic pregnancy is a serum hCG concentration of 1,500 mLu per mL (1,500 IU per L). When the ultrasound examination is negative, diagnosis requires a higher concentration of 2,000 mLu per mL (2,000 IU per L). Although ectopic pregnancies produce lower concentrations of hCG than normal pregnancies, a failure of the serum hCG concentration to double every two to three and one-half days in the fourth to eighth week of gestation and to reach a peak around the eighth to 12th week suggests an ectopic pregnancy. This finding can also be associated with early pregnancy failure. A two-day sampling interval is recommended if paired specimens are being tested.

Expectant management of ectopic pregnancy with spontaneous resolution is possible in some women, especially if the initial serum concentration of hCG is less than 1,000 mLu per mL (1,000 IU per L). Medical management is methotrexate, a folic acid antagonist, given intramuscularly or injected into the ectopic pregnancy sac. Close follow-up determinations of serum hCG levels are required, and substantial side effects can occur. Surgical management may be radical (salpingectomy) or conservative (usually salpingostomy). If persistent trophoblast is a risk, follow-up with serial measurements of hCG serum concentration is necessary.

The authors conclude that it is important to suspect ectopic pregnancy in patients who are sexually active and have a history of lower abdominal pain and vaginal bleeding, and that they should be evaluated with ultrasonography and serum hCG quantitation. Diagnostic laparoscopy may be necessary if the clinical situation is unclear or if the patient's condition deteriorates. Ectopic pregnancies could best be prevented by decreasing the incidence of pelvic inflammatory disease and C. trachomatis infections.