Double Decidual Sac Sign (DDSS)
Definition - What does Double Decidual Sac Sign (DDSS) mean?
A double decidual sac sign (DDSS) is a feature of an early pregnancy that can be visualized through a transvaginal ultrasound (TVUS) to confirm that a pregnancy is located within the uterus. An intrauterine pregnancy (IUP) is the only viable location for a pregnancy to develop. DDSS can be identified on an ultrasound as two (double) concentric rings or layers of decidua – one lining the uterine cavity and the other encircling the gestational sac.
FertilitySmarts explains Double Decidual Sac Sign (DDSS)
The DDSS is a useful feature to confirm an intrauterine pregnancy before the embryo or even the yolk sac can be seen. This is in contrast to the pseudogestational sac of an ectopic pregnancy that appears as a teardrop-shaped collection of fluid within the uterine cavity and is devoid of the normal double decidual sac sign. Ectopic pregnancies are not viable and can be life-threatening.
Although its presence is highly indicative of an intrauterine pregnancy, the double decidual sac sign is not seen in every IUP. Moreover, its absence does not necessarily represent a pseudogestational sac.
If the ultrasound fails to show an IUP, a repeat scan and serial beta-HCG levels will need to be done.