Question

Which of the following theory is postulated for placenta praevia?

• A. \( \text{Implantation theory} \)
• B. \( \text{Coelomic metaplasia theory} \)
• C. \( \text{Metastatic theory} \)
• D. \( \text{Dropping down theory} \)

Hint:

\textbf{Obstetrics: Placenta Praevia Etiology.} Understanding the dropping down theory helps in comprehending why placenta praevia might be diagnosed later in pregnancy even if early ultrasounds showed a normally located placenta.

Answer 1

The Correct Option is D

The most widely accepted theory for the etiology of placenta praevia is the dropping down theory. This theory suggests that the placenta initially implants in the upper segment of the uterus, but due to poor decidualization in the lower segment or other factors, it "drops down" later in pregnancy to cover or lie close to the internal cervical os. Let's briefly look at why the other options are not the primary theories for placenta praevia: \begin{itemize} \item Implantation theory: While abnormal implantation is the fundamental issue in placenta praevia (implantation in the lower uterine segment instead of the upper), the "dropping down theory" specifically explains how an initially higher implantation might lead to placenta praevia later in pregnancy. \item Coelomic metaplasia theory: This theory is related to the development of endometriosis, involving the transformation of coelomic epithelium into endometrial-like tissue, and is not associated with placenta praevia. \item Metastatic theory: This term typically refers to the spread of cancer cells to distant sites and is irrelevant to the development of placenta praevia. \end{itemize} Therefore, the dropping down theory is the most recognized explanation for the development of placenta praevia.