PAS results from defective formation of which uterine layer?

PAS results from defective formation of which uterine layer?

• A. Decidua basalis
• B. Myometrium
• C. Endometrium
• D. Perimetrium

Answer: (A)

PAS occurs when the decidua basalis fails to form properly, removing the barrier between placental villi and the underlying myometrium. Without this decidual layer, placental tissue invades into, or through, the myometrium, leading to placenta accreta spectrum (accreta, increta, or percreta). The decidua basalis is the maternal portion of the placenta formed by decidualization of the endometrium; the myometrium is the muscular layer, the endometrium is the lining that becomes decidualized, and the perimetrium is the outer covering—none of these provide the critical barrier when decidua basalis is defective.

PAS occurs when the decidua basalis fails to form properly, removing the barrier between placental villi and the underlying myometrium. Without this decidual layer, placental tissue invades into, or through, the myometrium, leading to placenta accreta spectrum (accreta, increta, or percreta). The decidua basalis is the maternal portion of the placenta formed by decidualization of the endometrium; the myometrium is the muscular layer, the endometrium is the lining that becomes decidualized, and the perimetrium is the outer covering—none of these provide the critical barrier when decidua basalis is defective.