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Double decidual sac sign

The double decidual sac sign (DDSS) is a useful feature on early pregnancy ultrasound in distinguishing between an early intrauterine pregnancy (IUP) and a pseudogestational sac. It consists of the decidua parietalis (that lining the uterine cavity) and decidua capsularis (lining the gestational sac) and is seen as two concentirc rings surrounding an anechoic gestational sac. Where the two adhere, is the decidua basalis, and is the site of future placental formation.

With good quality high frequency transvaginal scanning a yolk sac should also be present at this time.

Should a definite IUP not be confirmed on sonography then repeat scanning and serial quantitative beta-HCGs are required, until either an IUP is established, an ectopic pregnancy is visualised or beta-HCGs return to zero (implying miscarriage).

See also

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