PRISCA Software
for the Risk Calculation of Trisomy 21, Trisomy 18 and Neural Tube Defects

PRISCA* is a Windows^®-based software program that can be used to calculate the risk of Down's syndrome, trisomy 18 and neural tube defects (NTD). It accommodates double-test (AFP and HCG) and triple-test (AFP, HCG and unconjugated estriol) screening protocols. Same-day risk calculation is possible through laboratory automation.

Down's syndrome, or trisomy 21, is a congenital syndrome caused by triplication or translocation of chromosome 21. It occurs in approximately one out of every 700 live births. Abnormalities include mental retardation, a number of physical defects, and an increased incidence of leukemia and Alzheimer's disease by age 40. Reliable prenatal identification of fetuses with Down's syndrome can be accomplished only by karyotyping after amniocentesis during the second trimester of pregnancy, or by chorion villus sampling (CVS) at the end of the first trimester. If amniocentesis or CVS were performed on all patients routinely, however, a relatively high incidence of either spontaneous abortions or pregnancy complications would result.

In the late 1980s, a screening method was proposed for Down's syndrome that used a computer-assisted interpretation of AFP, HCG and unconjugated estriol tests along with gestational age, maternal age and other maternal characteristics.^1,2 Haddow et al.³ found that this method of screening for Down's syndrome would have made 75 percent of the amniocentesis procedures unnecessary in the women over 35 years old who were studied. The American College of Obstetricians and Gynecologists published a committee opinion firmly recommending that multiple marker screening be offered to women over age 35.⁴ Today, software-based maternal screening is a part of routine testing in the obstetrical care of pregnant women of all ages in the second trimester of pregnancy, and may reduce the need for amniocentesis in women aged 35 or more.

Any prenatal risk-calculation program, however, is a statistical program that may be used only as a screening test; it must never be used for diagnostic purposes. The risk calculation serves only to help the clinician and patient decide whether amniocentesis should be performed.

DPC is developing an export file for downloading data from the IMMULITE^® 2000 immunoassay analyzer directly into the PRISCA software. For more information on the PRISCA software or to learn how to obtain a demo version, please contact your National Distributor.

References

1. Cuckle HS, Wald NJ, Thompson SG. Estimating a woman's risk of having a pregnancy associated with Down's syndrome using her age and serum alpha-fetoprotein level. Br J Obstet Gynaecol 1987;94:387-402.

2. Canick JA, Knight GJ, Palomaki GE, Haddow JE, Cuckle HS, Wald NJ. Low second trimester maternal serum unconjugated oestriol in pregnancies with Down's syndrome. Br J Obstet Gynaecol 1988;95:330-3.

3. Haddow JE, Palomaki GE, Knight GJ, Cunningham GC, Lustig LS, Boyd PA. Reducing the need for amniocentesis in women 35 years of age or older with serum markers for screening. N Engl J Med 1994;330:1114-8.

4. American College of Obstetricians and Gynecologists. Down syndrome screening. (Committee opinion no. 141.) Washington, DC: American College of Obstetricians and Gynecologists, 1994.

*Available outside the US.