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Cardinal Glennon / Services & Programs / Fetal Care Institute / Twin Abnormalities / Selective Intrauterine Growth Restriction (sIUGR)

Selective Intrauterine Growth Restriction

Selective Intrauterine Growth Restriction (sIUGR) is a condition that occurs when monochorionic twins share unequal portions of the placenta. When twins have sIUGR one identical twin is normal size, while the other is significantly smaller. This condition occurs in 10-15% of monochorionic twins.

When a mother is pregnant with monochorionic twins there is an 80% the twins will share a placenta. Vessels on the surface of the placenta connect the babies’ circulation. When twins have sIUGR one twin has a smaller portion of the placenta, and has a harder time getting enough oxygen and nutrients. This causes it to be smaller than the other twin.

How is sIUGR Diagnosed?

A routine prenatal ultrasound will show whether there are twins in a pregnancy, and we can see if the twins are identical and sharing a placenta. This is a critical determination because if so, your babies are at risk for developing sIUGR.

At the SSM Health Cardinal Glennon St. Louis Fetal Care Institute, we recommend that screening ultrasounds be performed every two weeks between 16 and 24 weeks of the pregnancy for monochorionic twins (twins that share one placenta).

If signs of sIUGR develop, such as different amniotic fluid levels or growth differences, then ultrasounds can be performed more frequently to determine if the condition is progressing.

A fetal echocardiogram (echo) gives us much more information about the heart function and anatomy. Doppler technology is also used to assess the blood flow to babies’ brains, umbilical cords and other vital organs.

How is sIUGR Managed During Pregnancy?

A highly specialized maternal fetal physician should monitor sIUGR and determine if it is progressing. Progression can occur very rapidly, over a few days. If the smaller twin’s health declines too much, it can impact the well-being of the normal sized twin.

We examine each case closely, and our team of doctors and nurses explain the options for treatment of your specific case. The options include:

Observation Through Frequent Ultrasounds

Some cases of sIUGR may not require intervention, however it is important to monitor the twins frequently to note significant changes in the twins’ status. At the Fetal Care Institute, we often do ultrasounds every week.

Fetal Surgery

If the smaller twin is extremely ill it may be necessary to separate the twins’ shared blood flow to avoid compromising the lives of the babies. There are two fetal intervention procedures for sIUGR that can accomplish this: fetoscopic laser coagulation and cord occlusion.

Preterm Delivery

If the pregnancy is past 24 weeks gestation, and the babies’ lives are at risk, an emergency Cesarean birth may occur. Often the mother is hospitalized prior to delivery for fetal monitoring until the decision for delivery is made.

How does sIUGR affect my baby after delivery?

Twins with sIUGR vary dramatically after they are born. In many cases, if the normal sized twin is not born prematurely it will develop normally. If it is premature, it may face the challenges of most premature babies including respiratory problems, anemia and jaundice.

The smaller twin often has developmental and neurological deficits that will vary in severity. They may need assistance with breathing and feeding, and many will require a stay in the Neonatal Intensive Care Unit (NICU) after birth.

The nationally recognized neonatologists at the SSM Health Cardinal Glennon Children's Hospital's Dana Brown NICU have the experience and knowledge to provide the best care for these babies.

We understand that sIUGR can be a scary diagnosis. That’s why we’re available to help 24 hours a day, 7 days a week. For more information or to schedule an appointment, call us at 314-268-4037 or toll free at 877-SSM-FETL (877-776-3385). While we can’t change the diagnosis, we can provide you expert care and support, helping your baby get the most out of treatment and life.

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