Double decidual sign is seen in?
**Core Concept**
The double decidual sign is a sonographic feature observed during early pregnancy, referring to the presence of two layers of decidua parietalis and decidua capsularis surrounding the gestational sac. This sign is an important indicator of intrauterine pregnancy.
**Why the Correct Answer is Right**
The double decidual sign is seen when the decidua capsularis, which is the layer of endometrium surrounding the implantation site, is separate from the decidua parietalis, which lines the rest of the uterine cavity. This separation is due to the presence of the gestational sac, which is the fluid-filled structure that contains the embryo. The double decidual sign is typically seen on transvaginal ultrasound between 4-6 weeks of gestation. The presence of this sign helps to confirm the location of the pregnancy within the uterus.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the double decidual sign is not seen in ectopic pregnancy, where the embryo implants outside the uterus.
**Option B:** Incorrect because the double decidual sign is not seen in pseudogestational sac, which is a fluid-filled structure within the decidua basalis that does not contain an embryo.
**Option C:** Incorrect because the double decidual sign is not seen in a yolk sac, which is a fluid-filled structure within the gestational sac that does not contain an embryo.
**Clinical Pearl / High-Yield Fact**
The double decidual sign is an important diagnostic feature that helps to differentiate between an intrauterine pregnancy and an ectopic pregnancy. A thorough understanding of this sign is crucial for obstetricians and sonographers to accurately diagnose early pregnancy complications.
**Correct Answer: B. Pseudogestational sac**