Risk factors for ectopic pregnancy in women with symptomatic first-trimester pregnancies

ObjectiveTo evaluate the association between ectopic pregnancy (EP) and clinical and historical factors among women presenting with pain and/or bleeding in early pregnancy.DesignNested case–control study.SettingUniversity medical center.Patient(s)Women with symptomatic early pregnancies of unknown location presenting for care between January 1, 1990 and July 31, 1999.Intervention(s)None.Main Outcome Measure(s)Clinical and historical risk factors were compared between women with EP and women with ongoing intrauterine pregnancies or spontaneous abortions.Result(s)The following factors were associated with increased risk of EP: prior EP (odds ratio, 2.98 [95% confidence interval, 1.88–4.73] for one prior EP and 16.04 [5.39–47.72] for 2 or more), pelvic inflammatory disease history (1.5 [1.11–2.05]), pain at presentation (1.42 [1.06–1.92]), vaginal bleeding at presentation (1.42 [1.04–1.93]), and hCG of 501–2,000 mIU/mL (1.73 [1.24–2.42]). Age younger than 25 years (0.59 [0.41–0.85]) and a history of abortion were protective from EP (0.58 [0.38–0.90]). Prior nontubal pelvic surgery, past intrauterine device use, prior cesarean section, and current cervical infection demonstrated no association with EP.Conclusion(s)Evaluation of women with a symptomatic early pregnancy confirms and refutes some of the classical risk factors for EP. Prior EP is a strong risk factor, whereas pelvic inflammatory disease has an unexpected weak association. Previous abortion was found to have a negative association, whereas nontubal surgery, cesarean section, and a history of or concomitant cervical infection have no association. Knowledge of historical and clinical factors associated with EP may aid in early diagnosis.