Analysis of RAPP

To prevent complications during pregnancy and to prevent genetic and congenital anomalies in a future child, pregnant women undergo perinatal screening - a special set of examinations. This complex includes the determination of alfa-fetoprotein, chorionic gonadotropin, free estriol, placental lactogen, inhibin A, as well as analysis of PAPP and a number of other studies.

In this material, we will talk about the analysis of RAPP-A - plasma protein, the determination of which during pregnancy is of no small importance.

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Indications for the appointment of PAPP test

• Perinatal screening, which is carried out in order to assess the risk of chromosomal abnormalities of the embryo at 9-13 weeks.
• The previously observed complex pregnancies (spontaneous interruptions of pregnancies, fetal fetal early).
• The age of the pregnant woman is more than 35 years.
• Diseases of hepatitis, herpetic infection, cytomegalovirus, rubella during past pregnancies.
• If the family already has a child with chromosomal abnormalities or developmental defects.
• Genetic pathology in parents, siblings and pregnant women.
• The impact of radiation or other harmful exposures on one of the parents of a future child.

The analysis is usually done during 1-2 days. Taking blood is carried out in the morning, on an empty stomach. The day before you should not drink alcohol, sweets and overeat, as well as engage in heavy physical labor.

What does RAPP-A mean?

RARP-A is a special protein that begins to be produced in large quantities during pregnancy. Normally, there is a bit of this protein - a high molecular weight glycoprotein - in everyone: it is produced in the blood serum. However, in pregnant women, it begins to be synthesized by the trophoblast - the outer cell layer of the embryo, through which it is implanted into the wall of the uterus.

Analysis for plasma protein-A (RAPP-A) is prescribed in order to detect any violations of the developing embryo in time, since ultrasound at this time can not yet assess the formation and development of the fetus.

Specialists are inclined to believe that the change in plasma-protein-A is often associated with the risk of developing a Down's disease or other chromosomal abnormalities in a child. In addition, the change in indicators may indicate a threat of spontaneous interruption or stopping the development of pregnancy. For this reason, the analysis of RAPP-A is mandatory in the list of perinatal screening studies.

RARP during pregnancy is considered informative, starting with the 8th week of gestation, but often the doctors prescribe a PAPR test in combination with β-hCG, that is, from 11 to 14 weeks. Here it should be noted that the results of the PAPR analysis, which was carried out later than 14 weeks, can no longer be considered reliable, since from this time the plasma protein-A no longer serves as a marker of chromosomal abnormalities.

In order to confirm with certain accuracy the risk of developing a fetus of Down's disease and other anomalies, the doctor should consider not only the RAPP-A index directly, but also its correlation with the result of β-hCG and ultrasound.

The time interval between ultrasound and blood sampling for biochemistry (RAPP and hCG) should not exceed 3 days, otherwise the readings may be inaccurate. Along with the PAPR indices, hCG is determined simultaneously.

Results of RAPP-A

RAPP-A decoding is carried out by a specialist who takes into account the ratio of plasma-protein A, β-hCG, and ultrasound screening. In addition, the weight of the future mother's body, the facts of smoking pregnant, the conception with IVF, the intake of certain medicines, diabetes mellitus, and the presence of multiple pregnancies are necessarily taken into account.

There are different indicators of the RAPP rate for weeks of pregnancy. RAPP-A the table specifies the data depending on the term:

Week of pregnancy	The RAPP-A, md / ml
From 8th to 9th week	0.17-1.54
9 to 10 weeks	0.32 - 2.42
From 10 to 11 weeks	0.46-3.73
From 11 to 12 weeks	0.79 - 4.76
From 12 to 13 weeks	1.03-6.01
From the 13th to the 14th week	1.47 - 8.54

If RAPP-A is below normal, it may indicate that the future child has a risk of the following diseases:

• Edwards' disease is a violation of the 18 chromosome, which combines many anomalies of constitutional and mental development;
• Down's disease is an anomaly of 21 pairs of chromosomes, characterized by signs of a delay in mental and physical development;
• syndrome of "Amsterdam dwarfism" (Cornelia de Lange) - the disease of mutation of genes, which manifests itself in the delay of psychomotor development in different degrees;
• other chromosomal abnormalities (Rubinstein-Teibi's disease, mental underdevelopment with hypertrichosis, etc.).

For a pregnant woman, a decrease in PAPP-A may mean a threat of interruption or fading of pregnancy.

If RAPP-A is elevated, this is usually not a cause for concern: it may be that your gestation period is not set correctly, or that the outer cell layer of the fetus synthesizes more plasma protein than normal.

Do not forget that the result of the analysis of RAPP-A is not considered separately from the β-hCG and ultrasound test. Suspected chromosomal abnormalities in the fetus can only be in the presence of a combination of significantly reduced PAPP-A, increased β-hCG and a characteristic indicator for ultrasound, when the thickness of the collar space in the fetus is more than 3 mm.

Moreover, the result of the analysis of RAPP-A does not establish a diagnosis by 100%. It only makes it possible to determine the existence of the danger of chromosomal abnormalities, which determines the need for more careful monitoring of the course of this pregnancy.

MOM RARP-A - what is this?

In order to determine the degree of risk of chromosomal abnormalities, specialists use not so much the RAPP-A indices as the calculation of MoM.

MoM serves as a certain coefficient indicating the level of deviation of the perinatal screening indicator from the average for a particular week of pregnancy.

How to calculate MoM?

For this, the RAPP-A score should be divided by the average value corresponding to the week of pregnancy.

MOM RAPP-A norm is considered to be an indicator close to unity, but it can fluctuate in the range of 0.5-2.5, and with multiplicity it is up to 3.5MoM.

To survive ahead of time is by no means worthwhile: the results indicate only if a pregnant woman is at risk if possible development of chromosomal abnormalities. If there is such a risk, they will be watched carefully during the pregnancy, carrying out the necessary examinations and tests.

Of course, only you are given the right to decide whether to pass this or that analysis. After all, even having found chromosomal abnormalities in the fetus, medicine can not cure or correct them. Confirmation of the degree of risk only allows the future mother to decide: to keep the pregnancy and be ready for anything, or to interrupt her. Of course, in some cases, tests can be false positive, but no one can guarantee the result, unfortunately.

Tip: Regardless of whether you agree to take the RAPP test, or not, consult a good geneticist who will determine for you the need for further research.