Prenatal Diagnosis-Screening Combined Q1 (I)

The health of the mother and the fetus should be monitored throughout pregnancy. Under the medical point of view, the period of pregnancy is divided into 3 quarters and Q1 is of great importance, is the period indicated for realization of prenatal Screening (combined first trimester Screening).

Is the first quarter that can detect and reduce many health problems identifying themselves in the mother and the fetus. The performance in the first quarter of this screening enables pregnant women feel that they have a safe pregnancy, and there is a problem, can early counseling with your doctor.

According to the Fetal Medicine Foundation (FMF), an organization that promotes research in the field of fetal medicine, the combined first trimester screening has a 97% detection rate (in conjunction with the ultrasound), with 3% false positives.

What is the prenatal Screening-combined first trimester Screening?

The prenatal Screening-Combined Screening of Q1 is an early screening, which aims to assess the level of risk to the fetus of Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome).

Allows detection of 97% of the cases, for false positive rates of 3%, being a very important element to be taken into account by the couple, the decision to do an amnio or not. Amniocentesis involves obtaining a sample of amniotic fluid through a puncture in the abdominal wall of the mother guided by an ultrasound so that the specialist can drive the needle accurately, without risk of damage to the fetus or placenta. This test is usually performed under local anesthesia Administration prior. Amniotic fluid contains cells of the baby, which will after some time of culture, the study of chromosomes.

This combines the screening ultrasound examination information and biochemical examination.

What is ultrasound examination and biochemical examination?

The Ultrasound Examination makes it possible to determine with accuracy, gestational age through the skull-length (CCC/CRL), allows you to measure accurately the subcutaneous space located on the neck of the fetus (neck translucency-TN/NT) and assess the presence of Nasal bone (ON/NB).

Regarding the biochemical examination, this allows the determination of two substances present in maternal blood, the PAPP-A (pregnancy associated Plasma Protein) and ß-HCG (beta Subunit free Gonadotrófica Chorionic hormone), both with great sensitivity and specificity for the screening of anomalies.


Who is this test?

With maternity jeans made by, the risk of Trisomy 21 (Down syndrome), Trisomy 18 and as 13, increases with maternal age, especially from the 35 years, however often find young women with children suffering from Down syndrome. The Fetal Medicine Foundation (FMF) advises that the calculation of risk in the first quarter to all pregnant women, regardless of your age. If we consider only maternal age (> 35), as a criterion to throw human aneuploidy detection, this will allow only the detection of about 30% of cases.

In the case of being considered the maternal age and the ultrasound examination of the first quarter, these allow, together, a detection of about 75% of cases. When considering the maternal age, the ultrasound examination and biochemical examination (combined first trimester Screening), detection of about 95 to 97% of cases.

In a next article we will address the issue of when to perform the completion of prenatal Screening-combined first trimester Screening, as well as what are the main currently existing methods of diagnosis.