SUBCLASSIFICATION OF INDETERMINATE PELVIC ULTRASONOGRAMS - STRATIFYING THE RISK OF ECTOPIC PREGNANCY

Objective: To determine whether the subclassification of indeterminate ultrasound readings can identify patients who are at high, intermedia te, or low risk for ectopic pregnancy. Methods: A retrospective review was made of consecutive ED patients presenting to an urban teaching h ospital from August 1991 to December 1994 with abdominal pain and/or v aginal bleeding and a positive beta-hCG, Patients who had transvaginal ultrasonograms obtained during the ED visit that were read as indeter minate (no extrauterine findings of ectopic pregnancy and no intrauter ine fetal pole or yolk sac) were eligible, Ultrasonograms were subclas sified into 5 groups (empty uterus, nonspecific intrauterine fluid, ec hogenic debris within endometrial cavity, abnormal sac, normal sac) ba sed on predetermined criteria. Patients were excluded if the final dia gnosis could not be definitively determined. Results: 248 patients wer e identified, 20 patients were excluded because a final diagnosis coul d not be determined. Patients with an empty uterus [25/94 = 27% (95% C I 18-36%)] had the highest frequency of ectopic pregnancy. Patients wi th nonspecific intrauterine fluid collections [4/30 = 13% (95% CI 4-31 %)] had the next highest frequency of ectopic pregnancy. Patients with intrauterine echogenic debris [2/39 = 5% (95% CI 1-11%)], abnormal sa cs [1/36 = 3% (95% CI 1-9%)], or normal-appearing sacs [0/29 = 0% (95% CI 0-8%)] had low frequencies of ectopic pregnancy. Conclusion: Subcl assification of indeterminate ultrasound readings identifies patients at high, intermediate, or low risk for ectopic pregnancy and should im prove the diagnostic accuracy of ultrasonography in patients at risk f or ectopic pregnancy.