Prenatal genetic screening and diagnosis
Chromosomal and genetic screening is designed to assess whether a patient is at increased risk of having a fetus affected by a chromosomal or genetic disorder. Screening tests have been developed in an attempt to increase the antenatal detection rate of Down syndrome and other fetal trisomies and some other specific chromosomal abnormalities (trisomy 21,18,13 and sex chromosomes).
These screening tests include:
- The first-trimester nuchal translucency ultrasound scan or NT scan between the 11th and 14th week of gestation. The detection rate accuracy is 93% and if coupled with maternal serum biochemical markers and the combined screen test, the detection rate accuracy becomes 99.9%.
- Non-invasive prenatal testing NIPT or Cell-free fetal DNA testing: As some of your baby’s DNA winds up in your blood after 10 completed weeks of gestation, we take a blood sample from you, and a lab tests the baby’s DNA for trisomy 21,18,13 and sex chromosomes abnormalities with a high degree of accuracy. However, it is still a screening test and needs a confirmatory diagnostic test in cases of positive/high-risk results.
If any of your screening tests show a high risk for chromosomal abnormalities, we will suggest a diagnostic test (Chorionic villus sampling or amniocentesis) to confirm or role out the screening results.
If you and your husband have a certain genetic disorder or/and you have a baby affected with a genetic disorder (for example sickle cell anemia), the MFM specialist will offer you prenatal diagnostic testing for the fetus to be done by a Chorionic villus sampling at as early as 10 weeks gestation or by amniocentesis starting from 15 weeks gestation.
All couples with a history of genetic or chromosomal disorders will be offered detailed genetic counseling by a specialized pediatric geneticist in our center.
The objective of prenatal genetic screening and diagnostic testing is to reassure the parents when results are normal, and to detect disorders and health problems that could affect the woman, fetus, or newborn and provide the patient and her obstetrician-gynecologist or other obstetric care providers with enough information to allow a fully informed decision about pregnancy management ahead of time.