What diseases does the PAPP-A test detect? When should it be performed?

PAPP-A test – why should it be done?

Prenatal tests, which include the PAPP-A test, are designed to detect early the risk of genetic or developmental defects in the fetus. With their help, it is possible to plan appropriate treatment (while the pregnancy is still in progress or immediately thereafter) and prepare Parents for the possibility of raising a child who will require special care.

What does the PAPP-A test consist of?

The PAPP-A test is sometimes referred to as a duplicate test. It allows assessment of the concentration of PAPP-A protein, which is a protein synthesized in the trophoblast that has an immunosuppressive function. In addition to it, the level of the free subunit of chorionic gonadotropin, more specifically beta-hCG, is also determined. The Polish Gynecological Society recommends that the PAPP-A test be performed simultaneously with the evaluation of nuchal fold translucency by ultrasound.

The PAPP-A test is classified as a non-invasive method, which means that it does not interfere with the fetal environment. As a result, it is completely safe and has no risk of miscarriage. The test involves drawing a small amount of maternal blood from the elbow vein, which is then submitted for laboratory analysis. Importantly, the mother-to-be does not need to be fasting – the PAPP-A test will indicate a reliable result regardless of the food consumed.

When can a PAPP-A test be performed?

The PAPP-A test is performed between 11 and 14 weeks of pregnancy, i.e. during the first trimester. It is recommended to do it at the same time as an ultrasound, during which the doctor assesses nuchal translucency. This is a parameter whose elevated value can also indicate abnormalities. Performing two tests simultaneously increases their reliability.

What diseases does the PAPP-A test detect?

The PAPP-A test is designed to detect the risk of fetal trisomy, or the presence of an extra chromosome. Depending on which pair of chromosomes is abnormal, the child may have syndromes:

• Down ‘s (chromosome 21),
• 
  Patau
  (chromosome 13),
• Edwards (chromosome 18).

Other prenatal tests are used to detect other defects.

Abnormal PAPP-A test result

A low concentration of the test protein is considered a bad PAPP-A test result. It is then interpreted as an increased risk of Down syndrome. If at the same time the level of the free beta-hCG subunit is reduced, Patau or Edwards syndrome may be suspected. However, it should be borne in mind that a bad PAPP-A test result does not always mean that the baby is sick. For this reason, the mother-to-be is always referred for further diagnostics, i.e. invasive prenatal testing (such as amniocentesis).

It is worth remembering that a normal PAPP-A test result also does not guarantee that there is no risk of a genetic defect in the baby. For this reason, the doctor may recommend other non-invasive prenatal tests, such as the triple, integrated or NIFTY test.

What are the standards for the PAPP-A test?

Like most tests, the PAPP-A test also has designated standards that help specialists in diagnosis.

• The increased risk of having a child with Down syndrome may be evidenced by the results:

• Reduced concentration of PAPP-A protein (less than 0.5 MoM);
• elevated beta hCG hormone (above 2.52 MoM);
• Elevated nuchal translucency index.

• An increased risk of having a baby with Edwards or Patau syndrome may be indicated by the results:

• Reduced concentration of PAPP-A protein (less than 0.33 MoM);
• reduced levels of beta hCG hormone (less than 0.33 MoM);
• Elevated nuchal translucency index.

PAPP-A test reimbursement

The PAPP-A test is recommended for any pregnant woman, regardless of her age or other factors. However, this is a paid study. Its price ranges from 250 to 400 zlotys. The cost of the PAPP-A test may vary from lab to lab.

Reimbursement of the PAPP-A test is available to women who are in the risk group. They are covered by the National Health Fund program when:

• Are more than 35 years old,
• Have given birth to a child with a birth defect,
• have received abnormal ultrasound results,
• Are burdened with a genetic defect,
• there was a genetic defect in the partner’s family.

In order to benefit from reimbursement of the PAPP-A test, at least one condition must be met.

PAPP-A test vs. preimplantation diagnosis

Preimplantation diagnosis is used for genetic analysis of egg cells before or after fertilization. Using this method, embryos can be examined before being administered to the uterus of the mother-to-be. This type of health benefit is associated with assisted reproduction, such as in vitro. This test is performed to detect an abnormal number of chromosomes in an embryo. The recommendation for this type of analysis is also to diagnose the carriage of genetic diseases in any of the Parents.

FAQ:

• What is the PAPP-A test?

The PAPP-A test is a diagnostic tool designed to identify possible genetic defects associated with an abnormal number of chromosomes – thanks to it, diseases such as Down syndrome, Patau syndrome and Edwards syndrome can be detected.

• What indicators are considered in the PAPP-A test?

There are two factors that are analyzed during this test – the concentration of PAPP-A protein and the amount of free beta hCG, which is present in the pregnant woman’s serum. For this reason, professionals call this test the double PAPP-A test.

• Is the PAPP-A test result always reliable?

The test is considered very authoritative, nevertheless, if any disorders are detected, it is not the only analysis considered. In such a situation, the doctor recommends additional tests, such as the triple, integrated or NIFTY test.