Читать книгу Protocols for High-Risk Pregnancies - Группа авторов - Страница 54

In some programs, multiple markers in both the first and second trimesters are combined to optimize screening performance. The most common approaches include sequential screening, in which first‐trimester combined (serum and NT measurement) screening is performed and results provided. High‐risk patients are offered follow‐up with either cfDNA or diagnostic testing; patients at any risk level can also go on to have quad screening and be provided a final result including all serum analytes as well as the NT. This approach is associated with a 90–95% detection rate for trisomy 21 at a 5% false‐positive rate. It has the advantage of a high detection rate, the provision of a first‐trimester result, and the ability to screen for neural tube defects.

Integrated screening involves the same two‐step screening protocol, but results are not released until all screening steps are completed. This results in a lower false‐positive rate but has the disadvantage of later provision of results. A serum integrated screening approach, including first and second trimester serum analytes, can also be used in patients who do not have access to NT measurement. Again, this has the advantage of a relatively high detection rate but provides a later result.