What is selective intrauterine growth restriction (sIUGR)?
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 they share the same 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 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 gives us much more information about the heart function and anatomy. Doppler technology is also used to assess the blood flow to babies’ brains, ubilical 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 St. Louis 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.
- The St. Louis Fetal Care Institute is one of the only fetal care centers to offer fetoscopic laser coagulation for sIUGR. This procedure uses the same technique that is used in twins with twin-to-twin transfusion syndrome. It is performed between 18 and 26 weeks gestation.
A surgeon uses a laser to block the blood vessels that communicate between the twins. This new method of managing sIUGR ensures that the connecting blood vessels do not cause harm to the normal twin, while allowing the smaller twin to continue at its rate of development.
During this fetal surgery, the surgeon inserts a pencil-tip-sized telescope in the mother’s uterus and examines the entire placenta to find the crossing blood vessels. Once these are all mapped, a tiny laser fiber is inserted and laser energy is used to stop the blood flow between the twins. Separating the twin blood flow is like functionally separating the placenta, allowing each twin to develop independently.
Cord occlusion, which involves blocking the umbilical cord of the smaller twin, is not performed at the St. Louis Fetal Care Institute.
- Pre-term Delivery
- If the pregnancy is past 24-weeks gestation, and the babies lives are at risk, an emergency cesarean section may occur.
The staff at the St. Louis Fetal Care Institute is here to support you, arming you with knowledge about all of your options, and helping you decide what is right for you and your family. We will explain the risks and benefits of the various options, considering your specific case.
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 Cardinal Glennon Dana Brown NICU have the experience and knowledge to provide the best care for these babies.