Screening for Chromosomal and Congenital Anomalies

Screening for chromosomal and congenital anomalies has evolved significantly with the use of ultrasound. Adding Serum analytes to the evaluation of congenital anomalies has increased the detection rate. This addition includes maternal serum alpha fetoprotein (MSAFP), b-HCG, Estriol, Inhibin A, Free bHCG, and Pregnancy Associated Plasma Protein A (PAPP-A).

Sequential screening consists of two steps:

  1. Nuchal translucency (NT), with Free b-HCG and PAPP-A during the first trimester, and
  2. Quadruple testing during the second trimester.
    This modality takes the detection of trisomy 21 (T21) to 95%.

More recently, tests that measure the cell free fetal DNA (NIPT) in the maternal serum have become commercially available. The detection rate for T21 is 99%.

Many patients have opted for a first-trimester NT measurement, NIPT, and a 20-week ultrasound for anatomical survey. My concern and question to our group is where do we leave the MSAFP screening? Does your practice offer MSAFP to patients that opt for this approach?

Luis A. Izquierdo, MD, MBA, CPE, FAIUM, is a professor of OB GYN and Maternal Fetal Medicine at the University of New Mexico.