Maternal Serum Screening
GenPath offers several maternal serum screening tests that can be performed at specific times during a pregnancy. Each test assesses a patient’s risk for certain birth defects in pregnancy.
The following maternal serum screening tests are available through GenPath:
- Combined First Screen or Combined First Screen Plus
- Serum Integrated Screen
- Integrated Screen
- Sequential Screen
- Quad Screen
- Alpha-fetoprotein Screen
The chart below contains information on the detection rates (DR) and screen positive rates (SPR) for each of the maternal serum screening test options. Detection rate is the percentage of affected pregnancies that will be detected by the test. The screen positive rate is the number of women who will receive a result considered at increased risk.
| TEST | Down Syndrome | Trisomy 18 | ONTD |
|---|---|---|---|
| Combined First Screen | DR 85% SPR 5% | DR 90% | n/a |
| Combined First Screen Plus | DR 87% SPR 5% | DR 90% | n/a |
| Quad Screen | DR 83% SPR 5% | DR 77% | 85% when using 2.5 MoM |
| Integrated Screen | DR 95% SPR 2.15% | DR >95% | 85% when using 2.5 MoM |
| Serum Integrated Screen | DR 92% SPR 5% | DR 90% | 85% when using 2.5 MoM |
| Sequential Screen | 1st Tri: DR 62% SPR 0.6% 2nd Tri: DR 95% SPR 2.25% | 1st Tri: DR n/a 2nd Tri: DR 95% | 85% when using 2.5 MoM |
What does a screen positive result mean?
A screen positive result means that the patient is at a high risk for having a baby with one of the conditions included in the screen. A result is considered screen positive if the patient’s adjusted risk (based on screening results) is higher than or equal to the threshold risk level set for the screening test. A screen positive result is NOT diagnostic. If your patient receives a screen positive result, genetic counseling is recommended to discuss available testing options, which may include the option of diagnostic testing like chorionic villus sampling (CVS) or amniocentesis to determine whether the baby has the condition.
What does a negative result mean?
If the risk for each condition on the screen is below the threshold risk level for the screening test, then the result is called screen negative. Although a screen negative result means that the patient is not at high risk of having a baby with the tested conditions, a screen negative result does not completely rule out the possibility of a pregnancy with one of these conditions. A screening test cannot completely distinguish between an affected pregnancy and an unaffected one.
Advantages of risk assessments
Risk assessment by maternal serum screening is non-invasive, and it provides important information about a patient’s pregnancy and developing baby. If the pregnancy is found to be at risk for a serious birth defect, counseling is recommended to discuss the options for diagnostic testing and also to explain to the patient how their child’s physical and mental development could be affected.