INTERSTITIAL LINE - SONOGRAPHIC FINDING IN INTERSTITIAL (CORNUAL) ECTOPIC PREGNANCY

PURPOSE: To evaluate the relationship of the endometrial canal and dec idua vera to the interstitial gestational sac and to determine if this relationship can be used to increase the predictive value of ultrasou nd (US) in the diagnosis of interstitial ectopic pregnancy. MATERIALS AND METHODS: The US findings in 12 patients with interstitial ectopic pregnancy were reviewed. Radiologists also reviewed the cases of 40 pa tients with various diagnoses to assess the accuracy of the interstiti al line sign. RESULTS: US showed a definite gestational sac in four of the 12 patients (33%); the rest had a heterogeneous mass in the cornu al region. Thinning of the myometrial mantle was seen in these four pa tients. The gestational sac appeared eccentric in three of these but i n only three of 12 (25%) overall. The endometrial canal or interstitia l portion of the tube was identified in 11 of 12 patients (92%). The i nterstitial line had better sensitivity (80%) and specificity (98%) th an eccentric gestational sac location (sensitivity, 40%; specificity, 88%) and myometrial thinning (sensitivity, 40%; specificity, 93%) for the diagnosis of interstitial ectopic pregnancy. CONCLUSION: The inter stitial line sign is a useful diagnostic sign of interstitial ectopic pregnancy.