Obstetric Ultrasound Normal Pregnancy Vs Placenta Previa | Low-Lying, Marginal, Partial, Complete

Summary

In this video, Dr. Sam explains the condition known as placenta previa, where the placenta is abnormally positioned in the uterus, potentially obstructing the cervix. The causes, such as previous cesarean deliveries, multiple pregnancies, and maternal age, are explored. The video also covers how placenta previa is diagnosed, including its identification through imaging at different stages of pregnancy. Different types of placenta previa, including low-lying, marginal, partial, and complete, are explained with visual examples. The video emphasizes how these conditions are managed and how the placenta may shift in the third trimester.

Takeaways

• 😀 Placenta Previa is a condition where the placenta lies abnormally low in the uterus, potentially covering or being near the cervix.
• 😀 Risk factors for Placenta Previa include previous C-sections, multiple pregnancies, maternal age over 35, smoking, and a history of uterine surgeries or IVF.
• 😀 Placenta Previa is typically detected via ultrasound at 18-20 weeks of pregnancy, with follow-up scans at 28-32 weeks to monitor its progression.
• 😀 In some cases, Placenta Previa can resolve as the uterus grows, causing the placenta to move away from the cervix by the third trimester.
• 😀 If Placenta Previa is still present at 32 weeks, there’s a possibility it could still resolve by 36-37 weeks, especially in cases of low-lying or marginal Placenta Previa.
• 😀 A **Low-Lying Placenta** occurs when the placental edge is less than 2 cm from the cervix. It is not covering the internal os.
• 😀 A **Marginal Placenta Previa** is where the placenta is very close to the cervix but doesn’t cover the internal os.
• 😀 **Partial Placenta Previa** occurs when part of the placenta covers the cervix but not fully.
• 😀 **Complete Placenta Previa** is when the placenta completely covers the cervix, and it can be categorized as either symmetric or asymmetric based on the position of the placenta's center.
• 😀 **Symmetrical Complete Placenta Previa** has the center of the placenta aligned with the cervix, whereas **Asymmetrical Complete Placenta Previa** has the placenta covering the cervix, but the center doesn’t align with the os.

Q & A

What is placenta previa?

Placenta previa is a condition in which the placenta lies abnormally low in the uterus, either closer to the cervix or covering the internal opening (os) of the cervix.

What are the causes of placenta previa?

The causes of placenta previa include previous cesarean deliveries, multiple pregnancies, previous history of placenta previa, maternal age over 35, smoking, previous uterine surgeries such as fibroid removal, and in vitro fertilization.

At what stage of pregnancy is placenta previa typically diagnosed?

Placenta previa is typically diagnosed between 18 to 22 weeks of pregnancy, though some cases like low-lying placenta or marginal placenta previa may resolve by the third trimester (around 32 weeks).

Can placenta previa resolve on its own during pregnancy?

Yes, in some cases, such as low-lying placenta or marginal placenta previa, the condition can resolve by the third trimester as the uterus grows, leading to the migration of the placenta away from the cervix.

What is a low-lying placenta?

A low-lying placenta occurs when the placental edge is less than 2 cm from the internal os of the cervix. This is considered abnormal but may resolve by the third trimester.

How is a low-lying placenta diagnosed?

A low-lying placenta is diagnosed through imaging, where the distance between the placental edge and the internal os is measured. If this distance is 2 cm or less, it is considered a low-lying placenta.

What is the difference between marginal placenta previa and low-lying placenta?

In marginal placenta previa, the placental edge touches the margin of the cervix but does not cover the internal os. In contrast, a low-lying placenta has a placental edge that is less than 2 cm from the internal os but does not necessarily touch it.

What defines partial placenta previa?

Partial placenta previa occurs when part of the placenta covers the internal os of the cervix but does not completely obstruct it.

What is the distinction between a symmetrical and asymmetrical complete placenta previa?

A symmetrical complete placenta previa occurs when the central part of the placenta completely overlaps the internal os. In an asymmetrical complete placenta previa, the placenta covers the internal os but the central part of the placenta does not directly touch the os.

What is the significance of measuring the distance between the placental edge and the internal os?

Measuring the distance helps determine the severity of placenta previa. If the placental edge is 2 cm or less from the internal os, it may be classified as low-lying or marginal placenta previa, which can affect the management of the pregnancy.