Study objectives: To determine whether bedside endovaginal sonography (EVS) performed by emergency physicians reduces complications associated with ectopic pregnancy (EP) including missed EP and EP rupture. Methods: Our setting was an urban trauma center emergency department. We assembled a prospective convenience sample (n=314) with a historical EP control group (n=56) of women 18 years or older with a positive pregnancy test and any signs, symptoms, or risk factors for EP. Bedside EVS for all subjects and immediate quantitative serum human chorionic gonadotropin determination for patients with no definite intrauterine pregnancy by EVS. Results: Retrospective chart review identified 56 EP patients in the historical control group who had had no bedside EVS. Twenty-four of these patients (43%; 95% confidence interval [CI], 30% to 56%) were discharged from the ED, 12 of whom (50%; 95% CI, 30% to 70%) were later categorized as having ruptured EP. During the prospective study period, 40 patients were diagnosed as having EP; 11 (28%; 95% CI, 14% to 42%) were discharged from the ED (P=NS), and only 1 (9%; 95% CI, 0% to 26%) of the discharged patients was later determined to have a ruptured EP (P<.05). Conclusion: An EP protocol incorporating bedside EVS performed by emergency physicians significantly reduced the incidence of discharged patients with subsequent EP rupture, compared with historical controls. [Mateer JR, Valley VT, Aiman EJ, Phelan MB, Thoma ME, Kefer MP: Outcome analysis of a protocol including bedside endovaginal sonography in patients at risk for ectopic pregnancy. Ann Emerg Med March 1996;27:283-289.]