By integrating the information from both stages, the Iowa Integrated Screen is more effective than screening which uses information from Stage One or Stage Two alone. Integrated Screening is more effective at distinguishing affected from unaffected pregnancies because it has a lower screen-positive rate for Down syndrome and Trisomy 18 than single-stage screening options while still detecting the same number of affected pregnancies. A lower screen-positive rate reduces the chance that you will be offered a diagnostic test, such as an amniocentesis, which carries a small risk of complications, including miscarriage.
If you are too far along in your pregnancy for Stage One, the Iowa Integrated Screen cannot be done. However, women who are between 15-20 weeks of pregnancy may choose the Quad Screen, which measures the same markers as Stage Two of the Iowa Integrated Screen (AFP, hCG, uE3) plus a fourth marker, inhibin A. While the Quad Screen may have a lower detection rate and higher screen-positive rate than the Iowa Integrated Screen, it is still a good screen for Down syndrome, Trisomy 18 and open neural tube defects.
If you do not have the Stage Two blood test drawn between 15-20 weeks of the pregnancy we cannot report a result for the Iowa Integrated Screen. It is possible to determine a risk for Down syndrome and Trisomy 18 based on information from Stage One alone, as long as a nuchal translucency measurement has been performed by an NT-certified sonographer. This is called a First Trimester Screen. However, a First Trimester Screen alone has a higher screen-positive rate, making the screening less effective than the Iowa Integrated Screen. The First Trimester Screen alone also cannot screen for open neural tube defects.
The Iowa Integrated Screen is specifically designed to detect Down syndrome, Trisomy 18 and open neural tube defects. However, sometimes the result of an Iowa Integrated Screen will suggest the possibility of other problems with the pregnancy or the developing baby. It may indicate a risk for delivering the baby early or having a baby with a low birth weight. It also may indicate a problem with the placenta or the need for extra medical help before the baby is born or at the time of delivery.
An increased level of AFP, along with screening for open neural tube defects, may also suggest an increased risk for abdominal wall defects. An abdominal wall defect refers to an opening in the developing baby’s belly that causes the intestines to be on the outside of the body. Babies with abdominal wall defects need specialized medical care and surgery soon after birth. Those who receive the necessary medical care usually do well if they do not have other birth defects or genetic problems.
If you are carrying twins, the risk for open neural tube defects can be evaluated by determining the level of AFP in the second trimester only. This is called an NTD screen. We do not provide Down syndrome or Trisomy 18 screening for twins. We do not provide any screening for pregnancies with more than two fetuses.
One risk of this form of screening is anxiety for those who have a screen-positive result. It is always stressful to discuss the possibility that your developing baby may have a problem, and it is natural to be anxious or afraid. Fortunately, most women with a screen-positive result will have healthy babies.
If you choose to have an amniocentesis because of a screen-positive result, there is a small risk of pregnancy loss associated with this procedure. Ask the doctor who does the amniocentesis to discuss this possibility with you.
It is a shock to learn that your developing baby has a problem. You will need information about the specific condition and any treatment that may be available. There are two primary options to consider: you may begin to plan for the birth of a baby who may need special care after birth or you may choose to end the pregnancy.
Remember that it is more likely that your baby does not have Down syndrome, Trisomy 18 or an open neural tube defect, even if your Integrated Screening result is screen-positive. However, if your baby is found to have a problem, a physician, nurse, and/or genetic counselor will be able to discuss the specific condition and all of your options with you at the time the diagnosis is made.