Advantages


 


Prenatest
1st trimester


Prenatest
2nd trimester

Integrated Testing

Quad Test

Triple Serum Screen

Analytes measured


Free Beta-hCG

PAPP-A

NT

NB


Free Beta-hCG

AFP


1st trimester
PAPP-A
NT

2nd trimester
Total hCG
Inhibin A
Estriol
AFP


AFP

Estriol

Inhibin A

Total hCG


AFP

Estriol

Total hCG

Result availability


During the
1st trimester (between 11 and 14 weeks)

In the
2nd trimester

In the
2nd trimester

In the
2nd trimester

In the
2nd trimester

Specimen needed


Dry blood: necessitates only a finger prick

Dry blood: necessitates only a finger prick

Serum sample: necessitates a venipuncture

Serum sample: necessitates a venipuncture

Serum sample: necessitates a venipuncture


Legend
AFP: alpha-fetoprotein
hCG: human chorionic gonadotropin
NB: nasal bone
NT: nuchal translucency
PAPP-A: pregnancy-associated plasma protein-A

Prenatest Method

A prenatal screening test combining free Beta-hCG, PAPP-A, NT and NB. It is a proven and prospectively validated technology in over 200,000 pregnant women. It is used in the first trimester of pregnancy to determine the risk of Down syndrome with a very high sensitivity and specificity.

Integrated Test

A screening procedure in which both first and second trimester screening are performed. However, the first trimester screening results are not provided to the physician and patient but are withheld until after the results of second trimester screening are available, late in pregnancy. Physicians should also be aware that many laboratories offering this protocol are using a Down syndrome risk cut-off of 1 in 100. As a result, patients at moderately increased risk will not be offered the option of amniocentesis with this protocol. Further, physicians should be aware that 20-30% of patients will not undergo first or second trimester screening steps and could have no final Down syndrome screening results. Since the patient needs to have two different blood draws, the cost is higher for the patient.

Quad Test

A second trimester test consisting of AFP, total hCG, inhibin A and unconjugated Estriol (uE). The test can detect about 70% of Down syndrome cases with an expected false positive rate of 5%. Some studies have observed a false positive rate significantly higher than 5%.

Triple Serum Screen

Triple test that includes only AFP, total hCG and unconjugated Estriol (uE), has a higher false positive rate when compared with the Quad test.