Following declining human chorionic gonadotropin values in pregnancies of unknown location: when is it safe to stop?

ObjectiveTo determine if the pattern of decline in hCG curves can discriminate spontaneous abortion (SAB) from ectopic pregnancy (EP).DesignRetrospective cohort study.SettingUniversity hospitals.Patient(s)A total of 1,551 women with symptomatic pregnancy of unknown location (PUL) and decreasing hCG values.Intervention(S)None.Main Outcome Measure(s)Percentage change in hCG; days and visits to final diagnosis.Result(s)Of the 1,551 women with a PUL and declining hCG, 146 were ultimately diagnosed with EP and 1,405 with SAB. An 85% hCG drop within 4 days or a 95% hCG drop within 7 days both ruled out an EP 100% of the time. Applying the 4-day cutoff to this population would have saved 16% of the SAB population (229/1,405) a total of 2,841 person-days and 277 clinical visits. Applying the 7-day cutoff would have saved 9% of the SAB population (126/1,405) a total of 1,294 person-days and 182 clinical visits. These cutoffs were separately validated on a group of 179 EPs collected from three university clinical centers. In that population, each cutoff separately ruled out EP 100% of the time.Conclusion(s)The decline in serum hCG is slower in EPs than in SAB and can be used to aid clinicians in the frequency and duration of follow-up. Costs and patient time may be saved by allowing women who meet one of these criteria to be followed less frequently.