A Severed Connection

Early Detection of Vasa Previa Can Save Lives By Teri Brown

The umbilical cord, that precious link from Mother to unborn baby, seems to carry not only nutrients and oxygen-rich blood, but hopes and dreams. When that connection fails, dreams are dashed. With vasa previa, a rare condition where the vessels of the cord grow on its exterior, the results are usually fatal – unless a Cesarean section is performed.

What is Vasa Previa?
In cases of vasa previa, the blood vessels run through the umbilical cord for some distance, then grow out of the cord and into the placenta. Without the tough fibrous cord, these fragile blood vessels have minimal support, with the only real support being the fetal membranes, or bag of waters.

The stress of labor and the bursting of the water sac often causes the vessels to tear. This results in the rapid death of the baby from blood loss. The mortality rate from undetected vasa previa is high, from 50 percent to 90 percent.

Little is known about what makes the vessels grow out of the cord. One reason may be that the nutrients in the bottom of the placenta are not as rich as the nutrients in the top of the placenta. The vessels may grow toward the better nutrition, just as a plant grows toward the sun.

Know the Risk Factors
Though no one knows exactly what causes vasa previa, there are some factors women should be aware of that place them at greater risk for developing the condition:

• Women with low-lying placentas (near or over the cervix)
• Multiple pregnancies
• Pregnancies resulting from in vitro fertilization
• Bi-lobed placentas (the placenta consists of more than the usual single piece)

Vasa previa without the presence of these risk factors is extremely rare.

Early Identification Is Vital
Dr. Yinka Oyelese, a fellow in maternal fetal medicine at the Robert Wood Johnson Medical School in New Jersey, has put together, in conjunction with the Vasa Previa Foundation, a database of vasa previa cases from around the world. Still, Dr. Oyelese says, there is more to be learned about the treatment of this condition.

The heartbreak of vasa previa lies in the number of babies who perish due to a lack of diagnoses. According to Dr. Oyelese, when undiagnosed before labor, two-thirds of babies with the condition will die. If it is diagnosed and a C-section is performed, practically all babies survive.

"Clearly, the only way to prevent this happening is to identify women who have vasa previa before the membranes rupture," says Dr. Oyelese. "They can then be delivered by Cesarean, which avoids the membranes rupturing over the cervix."

Medical professionals can identify vasa previa using ultrasound, though Dr. Oyelese explains that Color Doppler helps because it displays blood flow through blood vessels in color. If there are abnormal vessels running over the cervix, they can be identified.

"It is currently not standard practice to look for vasa previa," says Dr. Oyelese. "However, it is easy and does not take extra time or demands on personnel or equipment in most modern obstetric ultrasound units. So this can be done as a part of the routine ultrasound scan."

"Thus, the onus should not be on the women," says Dr. Oyelese. "Rather, a change in ultrasound screening protocols will have the greatest impact on reducing mortality from vasa previa."

Want to see more?

• Just in Case: Making a Plan for Cesarean Birth
• Managing Pregnancy Complications Series
• High Tech Babies: In Vitro Fertilization
• Talk about it!

About the Author: Teri Brown is a senior contributing writer for iParenting Media.