<prompt> The double decidual sac sign DDSS is the best method for ultrasound diagnosis ofMonoamniotic Dichorionic twinsDiamniotic dichorionic twinsEctopic pregnancyNormal pregnancy  <response>: Double decidual sac sign on USG - Intra-uterine sac Eccentrically placed Outer layer - Decidua Parietalis Inner layer - Decidua Capsularis Indicates - Intrauterine pregnancy Intradecidual ring sign is the first sign of pregnancy on USG. 