Which decidual layer lines the remaining portion of the uterine cavity not occupied by the implanted conceptus?

Which decidual layer lines the remaining portion of the uterine cavity not occupied by the implanted conceptus?

• A. Decidua Basalis
• B. Decidua Capsularis
• C. Decidua Parietalis
• D. Double Decidua Sign

Answer: (C)

In early pregnancy, the endometrium forms distinct decidual layers around the conceptus. The portion of the uterine cavity not occupied by the implanted embryo is lined by the decidua parietalis (also called decidua vera). The layer directly over the conceptus is the decidua capsularis, and the area under the implantation site is the decidua basalis. As the pregnancy grows, the capsularis and parietalis eventually fuse, narrowing the cavity. The double decidual sign is an ultrasound appearance of two decidual layers around the sac, not the separate lining itself.

In early pregnancy, the endometrium forms distinct decidual layers around the conceptus. The portion of the uterine cavity not occupied by the implanted embryo is lined by the decidua parietalis (also called decidua vera). The layer directly over the conceptus is the decidua capsularis, and the area under the implantation site is the decidua basalis. As the pregnancy grows, the capsularis and parietalis eventually fuse, narrowing the cavity. The double decidual sign is an ultrasound appearance of two decidual layers around the sac, not the separate lining itself.