Objective: To evaluate quantitative hCG measurements and transvaginal ultrasound in the diagnosis of ectopic pregnancy in patients presenting to the emergency department.
Methods: A discriminatory zone for detecting the presence or absence of an intrauterine pregnancy by transvaginal ultrasound was established prospectively. Women presenting to the emergency department were evaluated prospectively using a diagnostic algorithm consisting of clinical examination, quantitative serum hCG, and transvaginal ultrasound. Finally, ectopic pregnancies diagnosed over a 22-month period were evaluated prospectively.
Results: All viable intrauterine pregnancies were identified in those subjects with hCG levels of 1500 mIU/mL (First International Reference) or greater. One thousand two hundred sixty-three subjects were evaluated prospectively; 59.8% were diagnosed with intrauterine pregnancy, 26.8% with spontaneous abortion, and 7.8% with ectopic pregnancy. At presentation, 13.2% of intrauterine pregnancies were diagnosed by clinical examination, whereas 82.9% were diagnosed by transvaginal ultrasound. Only 4% of normal intrauterine pregnancies were not confirmed on initial visit. Of 205 ectopic pregnancies diagnosed, 81.5% were hemodynamically stable; of these, 49.1% were diagnosed on initial presentation. Of all ectopics, 59% never reached an hCG level of 1500 mIU/mL and 35.8% had an hCG lower than the level at presentation. This protocol diagnosed ectopic pregnancies with a sensitivity of 100% and a specificity of 99.9%.
Conclusion: A protocol of quantitative hCG levels (available within hours of presentation to an emergency department) combined with transvaginal ultrasound is effective in diagnosing ectopic pregnancy.