> Amniocentesis: invasive prenatal diagnosis

Is used for the diagnosis of genetic diseases (chromosomal abnormalities, molecular and metabolic), and of some infectious diseases (toxoplasmosis, rubella, CMV).


  • Perché after 35?
  • the

  • amniocentesis
  • the

  • ultrasound of The II quarter
  • the

  • with The ultrasound and genetics
  • the

  • ultrasound of The III quarter

In particular, the indications for the investigation of cytogenetic for chromosomal abnormalities of a fetus are:

Età advanced maternal (= or > 35 years)

Parents with a previous child affected by a chromosomal pathology

Parent is a carrier of a structural rearrangement not associated with phenotypic effect

Parent with aneuploidy of the sex chromosomes are compatible with the fertilityà

Abnormalities, malformations highlighted sonographically

Probability; of 1/250 or greater that the fetus is suffering from Down’s syndrome or some other aneuploidy on the basis of the biochemical parameters assessed on maternal blood or ultrasound.

The invasive prenatal diagnosis può to provide information mainly on chromosomal abnormalities. The research of some other genetic abnormalities is not routinely performed, but only in the presence of a risk family member or a precise indication. No indication, however, will comeà delivered in respect of all the other congenital anomalies.

most of The genetic diseases diagnosed prenatalmente can not be prevented né cured or treated effectively, even if considerable progress has been achieved therapeutic for some diseases (such as bone marrow transplants in thalassemia), and many others will still be able to come from gene therapy.

A possible option permitted by law 194/78 is the voluntary termination of pregnancy. the

Perché after 35?

The incidence of trisomies of the fetus is directly proportional to the età maternal. The risk of having a child with Down syndrome increases in a linear fashion up to about 30 years and then exponentially. The medical practice currently accepted is the offer of routine invasive prenatal diagnosis to women with more than 35 years.

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This practice is motivated by the fact that this età an increased risk of the mother having a fetus with chromosomal abnormalities (about 1/270) counterbalances the risk of miscarriage related to the procedure (about 1/200).

it Is useful, however, to remember that if all women with età equal to or greater than 35 years to do the amniocentesis will identify only 30% of children with Down syndrome. In fact, 70% of children with trisomy 21 are born to women less than 35 years old. the In Italy, after 35 years, amniocentesis is the responsibility of the NHS but is not obligatory.

The test.

it Is a technique that consists in drawing with a needle, of a sample of amniotic fluid via transabdominal. The period of execution is usually after the 16th week up to the 18th.

amniocentesis carries a risk of fetal loss of 1%. The risk increases significantly in the presence of the previous abortività (up to 7%), presence of genital bleeding during pregnancy (up to 6%), blood in the amniotic fluid (up to 15%).

After amniocentesis there is a risk of rupture of membranes of approximately 1%. Other risks are: isoimmunisation, and transmission of viral diseases. In 0.2% of cases, può be sure to check the failure of the examination due to contamination with blood or other reasons. In the 0.2-0.5% of the cases, può to have as a result a mosaicism mobile phone and in this case it is necessary to repeat sampling. The diagnostic errors in the laboratory are negligible. The amniocentesis test può be booked at our hospital by calling the number: 06/68352280. (H24)

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The ultrasound of the second quarter.

This type of ultrasound has as its main purpose the evaluation of the anatomy of the fetus. For this purpose, it is recommended to run between 19 and 21 weeks. The ability to detect an abnormality is greater depends on its entityà, from the position of the fetus in the uterus, from the quantityà of the amniotic fluid and by the thickness of the abdominal wall maternal; thereforeò è possible that certain fetal abnormalities may not be detected at the ultrasound examination.

in Addition, some malformations occur late (7°-9° month) and thereforeò are not viewable in the examinations early. The experience gained so far suggests that an ultrasound examination-routine, non-targeted, allows you to identify from 30 to 70% of major malformations.

there is the task of the ultrasound in the detection of the so-called minor abnormalities. It is, therefore, possible that some of the abnormalities is also important not to be detected by ultrasound. This exam can be booked at our hospital by calling the number: 06/68352280. (H24)

ultrasound genetics.

In fetuses with chromosomal abnormalities, ultrasound can; highlight a series of sonographic findings, commonly called soft markers, which are not the expression of the malformation, but they have a character that is often transitional. Furthermore, they are not specific in the sense that you can also detect in normal fetuses. The observation that fetuses with chromosomal abnormalities arise with greater frequency, some of the soft markers alone or associated between them has created the concept of ultrasound and genetics.

this term refers to an ultrasound examination, which is conducted in the second trimester of pregnancy, usually between 15 and 19 weeks, in order to check the presence of soft markers in order to refine the a priori risk (generated by the età maternal or by a biochemical test positive) chromosomal abnormality. In women in età advanced or tri-positive test, ultrasound, genetics has shown a sensitivityà of 60-80% with a false positive rate of 5-19%. This exam can be booked at our hospital by calling the number: 06/68352280. (H24)

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The ultrasound of the third quarter.

The purpose of this ultrasound is to evaluate the fetal growth (locate that is; all those conditions of delay that puts at risk the fetus), and to view the placenta and finally to evaluate the amounts and categories of the amniotic fluid. In the course of this examination, however, can be detected malformations, late onset. Può be run from the 26th week until term of pregnancy. The ultrasound can also be booked at our hospital by calling the number: 06/68352280. (H24)

summary of procedures for prenatal diagnosis according to gestational age

Ospedate S. Spirito in Saxia Rome – UOC of Obstetrics and Gynecology Director: Prof. Vincenzo Scotto di Palumbo Lg. The tiber Sassia – 06/68351

prenatal diagnosis – invasive prenatal Diagnosis – The advice preconcezionale – Symptoms of pregnancy – maternal health

Calendar of pregnancy online

Test on fetal dna in maternal blood NIPT, as it should be used

prenatal Testing non-invasive: why is it and what are the risks

Amniocentesis free of charge only after other blood tests


Page updated on September 22, 2007