2012-05-19
PRISCA-II (AFP, HCG, uE3) – test is performed 14 + 3 d. - 22 week of pregnancy
PRISCA (Prenatal Risk Calculation) is a noninvasive test of blood of pregnant women allowing by using computer software to calculate risk of chromosomal diseases and other malformations based on concentration of several biochemical markers and other data of pregnant women.
Probability of birth of infant with chromosomal disease is low, however it exists. Approximately 70 percent of miscarriages occur due to chromosomal abnormality of fetus. However, sometimes such embryos survive, and infants with incurable chromosomal disease are delivered. The most frequent abnormalities are Down's syndrome and Edwards’ syndrome.
Various factors cause malformation of fetus: inherited from parents’ genetic abnormalities or fetus malformations caused by harmful environmental factors or incidental cell division mistakes. Sometimes absolutely healthy parents give birth to infants with abnormalities exactly due to this reason.
In order to lower risk of birth of infants with Down's syndrome, Edwards’ syndrome and neuraxial lesions, special software for estimation of risk of chromosomal diseases, PRISCA, based on the evaluation of biochemical markers of maternal blood was developed.
In some countries PRISCA test is performed to all pregnant women; in Lithuania this test is recommended, yet it is not mandatory.
PRISCA is recommended to all pregnant women irrespectively to their age. It is better to perform this test twice: during the first trimester and during the second trimester of pregnancy.
Test is performed:
During THE FIRST trimester of pregnancy (PRISCA-I): from 11th week to 13th week+ 6 days of pregnancy.
During THE SECOND trimester of pregnancy (PRISCA-II): from 14th week + 3 days to 22nd week of pregnancy.
During PRISCA-I test the following parameters of patient’s blood are measured:
PAPP-A (Pregnancy Associated Plasma Protein A);
β-HCG (free beta human chorionic gonadotropin);
At ultrasound examination (UE) nuchal translucency (NT) is measured.
NT is an additional examination (performed from the 11th week of pregnancy) highly enhancing accuracy of PRISCA-I test (data are presented in the table).
NT measurement may be (for your convenience) performed in SOPRO medical investigation center. NT is evaluated by physicians. This examination must be performed at the same day (o not later than after 1 or 2 days) as the measurement of two other indicators.
Reliability of PRISCA-I test:
| Week of pregnancy | Evaluation by two indicators: PAPP-A and β-HCG |
Evaluation by three indicators: PAPP-A, β-HCG and NT |
| 11th week | 58 percent | 84 percent |
| 12th week | 51 percent | 81 percent |
During the first trimester of pregnancy risk for baby to be born with Down’s syndrome and Edwards’ syndrome is evaluated.
During PRISCA-II test the following parameters of patient's blood are measured:
AFP (alpha fetoprotein);
HCG (human chorionic gonadotropin);
u-Estriol (free unconjugated estriol).
During the first trimester of pregnancy risk for baby to be born with Down’s syndrome, Edwards’ syndrome and neuraxial damage is evaluated.
The following data of pregnant woman are necessary to calculate risk of malformations: date of birth, weight, smoking, concomitant diseases.
Pregnancy data: twins, artificial insemination, duration of gestation (duration of gestation could be calculated by the date of last menses and according to data of ultrasound examination).
It is necessary to fill referral form for PRISCA test carefully because all additional data are important for reliability of test results.
How PRISCA results should be understood?
According to the results of the examination of pregnant woman, PRISCA software calculates probability of malformations arising during current pregnancy. For example, ratio 1:400 shows that one of every four hundred of pregnant women has a chance to deliver baby with corresponding malformation.
Results could be compared with the average risk for women of this age group presented by the software.
When increased risk of chromosomal abnormalities is established during PRISCA test, it is recommended to perform more precise test, evaluation of specimen of amniotic fluid, so called FISH test.
To perform test, venous blood specimen should be obtained. Blood specimens are taken every day.
PRISCA-I test is performed on Wednesdays, PRISCA-II test is performed on Tuesdays and Thursdays, test results are given within 2 days from the beginning of testing.
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