Sequential Integrated Screening has three separate steps: Two blood tests and one ultrasound.
First trimester blood test (10-13 wks): human chorionic gonadotropin (hCG) and pregnancy-asssociated plasma protein-A (PAPP-A). These substances are normally found in a woman’s blood only during pregancy.
Nuchal translucency ultrasound (11-14 wks): ultrasound measures thesize of the nuchal translucency of the fetus. Increased NT is greater than 3mm.
Second trimester blood test (15-20 wks): alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), unconjugated estriol (uE3), and inhibin-A (INH). These substances are made by the placenta and the fetus.
Conditions included in the California Prenatal Screening Program:
| Condition | 1st trimester | NT | 2nd trimester |
| Trisomy 21 | Decreased PAPP-A Increased hCG |
Increased | Decreased AFP Decreased estriol Increased hCG increased inhibin A |
| Trisomy 18 | Decreaaed PAPP-A Decreased hCG |
Increased | Decreased AFP Decreased estriol Decreased hCG Dcreased inhibin A |
| NTDs | – | – | Increased AFP |
| Abdominal wall defects | – | May be increased | Increased AFP |
| Smith-Lemli-Opitz | – | May be increased | Decreased Estriol |
Newborn screening program screens for 80 conditions (CF, endocrine disorders, metabolic disorders, hemoglobinopathies, SCID) on nearly all California babies.
Collected at least 12hrs after birth, on discharge, prior to a red blood cell transfusion, or on 6th day of life for infants with extended hospital stays.