Objective: Our aim was to determine the accuracy of the intradecidual sign for the diagnosis of intrauterine pregnancy and the exclusion of ectopic pregnancy.
Conclusion: The intradecidual sign reliably excludes the presence of an ectopic pregnancy. The sensitivity for diagnosis of an intrauterine pregnancy increases when human chorionic gonadotropin levels are equal to or greater than 2,000 mIU/mL or the mean sac diameter is equal to or greater than 3 mm. It is of utmost importance to visualize this sign on multiple views with an unchanging appearance.