Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy.

OBJECTIVES: Pelvic ultrasound performed by emergency physicians can identify a definite diagnosis in the majority of symptomatic first-trimester pregnant patients on the initial emergency department (ED) visit. However, a significant minority of such patients are diagnosed as having an indeterminate pregnancy state requiring further testing and consultation. The authors investigated the final outcome of patients with an initial indeterminate ED first-trimester pelvic ultrasound examination in the setting of an interdepartmental protocol to rule out ectopic pregnancy.

METHODS: This was an observational prospective cohort study performed at a regional, urban ED with more than 100,000 patient visits over a 13-month period. Pelvic ultrasound for first-trimester patients was prospectively performed by emergency physicians with gynecologic consultation for lack of intrauterine pregnancy (IUP) ultrasound findings. IUP was defined as a fundal gestational sac with either a yolk sac or a fetal pole. Pelvic ultrasounds were classified into diagnostic categories including definite IUP, embryonic demise, molar pregnancy, definite ectopic pregnancy, and indeterminate. For all patients with indeterminate pelvic ultrasound findings, final diagnostic categories and patient outcome were established by the use of patient records, obstetric ultrasound reports, laboratory studies, operative reports, and pathology reports. All patients with ectopic pregnancy were followed for mode of treatment. Descriptive statistics were calculated.

RESULTS: A total of 1,490 ED first-trimester pelvic ultrasound examinations were performed over 13 months establishing the following diagnostic rates for initial ED visit: IUP 1,037 (70%), demise 127 (8%), definite ectopic pregnancy 24 (2%), molar pregnancy 2 ( < 1%), and indeterminate 300 (20%). The 300 indeterminate patients were classified using the above protocol into the following final diagnostic categories: embryonic demise 158 (53%), IUP 88 (29%), ectopic pregnancy 44 (15%), and unknown outcome 10 (3%). Indeterminate patients with ectopic pregnancy were treated with methotrexate in 25 of 44 cases (57%) and surgically in 16 of 44 cases (36%); there were no laparotomies. In contrast, ectopic pregnancy patients diagnosed on initial ED visit were treated surgically in 20 of 24 cases (83%), including four laparotomies.

CONCLUSIONS: The outcome of symptomatic first-trimester patients with indeterminate ED pelvic ultrasounds is poor, with significantly high rates of embryonic demise and ectopic pregnancy. However, those indeterminate patients with the eventual diagnosis of ectopic pregnancy have a higher rate of medical methotrexate treatment and a reduced rate of invasive surgical treatment compared with ectopic pregnancy patients diagnosed at initial ED visit.