Placenta & Umbilical Cord Findings

The placenta can attach in different areas of the uterus, including the front (anterior), back (posterior), top, or side. These are all normal locations. If you have an anterior placenta, it may take a little longer to feel your baby's movements because the placenta sits between the baby and the front of your abdomen.

A low-lying placenta means the edge of the placenta is close to the cervix but does not cover it.
Placenta previa means the placenta partially or completely covers the opening of the cervix.

When a low-lying placenta or placenta previa is identified earlier in pregnancy, there is a good chance it will no longer be close to the cervix later in pregnancy as the uterus grows. We will usually repeat an ultrasound around 28 weeks to reassess the placental location and continue to follow it if it remains low.

A low placenta generally does not affect your baby's growth or development, but if it remains close to or covering the cervix later in pregnancy, it can affect how and when your baby is delivered. We will discuss the safest delivery plan based on the placenta's location as your pregnancy progresses.

• Placenta Previa (Yale)

• What is Placenta Previa (Scripps Health, video)

Most placentas develop as a single disc of tissue. Sometimes the placenta develops with a different shape or structure. These findings are often identified on ultrasound and may lead us to take a closer look at the placenta, its blood vessels, or your baby's growth.

Accessory (Succenturiate) Lobe
An accessory or succenturiate lobe is a smaller area of placental tissue that develops separately from the main placenta. Blood vessels may travel through the membranes between the two areas, so we will look carefully at where those vessels are located.

Bilobed Placenta
A bilobed placenta develops as two larger sections rather than one single placental disc. Ultrasound can help us evaluate how the sections are connected and where the umbilical cord and blood vessels are located.

Circumvallate Placenta
A circumvallate placenta occurs when the membranes fold back around the edge of the placenta, giving the placenta a thicker or raised appearance around its margin. This may be suspected on ultrasound, although it can sometimes be difficult to diagnose with certainty before delivery. Depending on the appearance and the rest of the pregnancy, we may recommend additional ultrasound follow-up.

The umbilical cord usually attaches near the center of the placenta and contains three blood vessels: two arteries and one vein. Sometimes ultrasound shows a difference in where the cord attaches or in the number or location of these blood vessels. Many of these findings do not cause problems, but some may lead to additional ultrasound monitoring or affect planning for delivery.

Marginal Cord Insertion
The umbilical cord attaches near the edge of the placenta rather than closer to the center. We may recommend additional ultrasound monitoring of your baby's growth later in pregnancy.

Velamentous Cord Insertion
The umbilical cord attaches to the membranes next to the placenta rather than directly into the placental tissue. Some of the baby's blood vessels then travel through the membranes before reaching the placenta. We may recommend additional ultrasound monitoring depending on the location of these vessels and your baby's growth.

Vasa Previa
Vasa previa occurs when unprotected fetal blood vessels travel through the membranes over or very close to the cervix. This is different from placenta previa. Because these vessels could be injured when labor begins or the water breaks, vasa previa requires closer monitoring and changes how and when delivery is planned.

• Vasa Previa (SMFM)
  
  

Two-Vessel Cord / Single Umbilical Artery

Most umbilical cords contain three blood vessels: two arteries and one vein. A two-vessel cord, also called a single umbilical artery, has one artery and one vein. Many babies with an isolated two-vessel cord develop normally, although we may take a closer look at your baby's anatomy and recommend additional monitoring of growth later in pregnancy.