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INTRODUCTION

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Definitions

  1. Amniocentesis with a filtration technique: amniocentesis performed with a filter membrane between the syringe and the needle to recirculate the amniotic fluid back to the amniotic cavity, and to obtain the amniotic fluid cells directly from the filter membrane.

  2. Early amniocentesis: procedure that is performed before 15 weeks of gestation.

  3. Fluorescence in situ hybridization (FISH): cytogenetic technique used to detect the presence or absence of specific DNA sequences on chromosomes. It uses fluorescent probes that bind to only those parts of the chromosome with which they show a high degree of sequence similarity. This technique is commonly used in genetic counseling and species identification.

  4. Gram stain: most widely used staining technique in bacteriology to distinguish between gram-positive and gramnegative bacteria based on the ability of the cell wall of the organism to retain crystal violet, the primary stain of this method. Grampositive bacteria retain the crystal violet stain and look purple under microscopic examination, while gramnegative organisms look pink due to decolorization by an organic solvent and exposure of fuchsin, a counterstain.

  5. Kleihauer-Betke test: test performed in maternal blood in order to evaluate the degree of fetomaternal transfusion after miscarriage, abortion, invasive procedures, trauma, or delivery by determining the amount of fetal hemoglobin transferred from the fetus to the maternal circulation. This test also allows determining the dosage of anti-D immunoglobulin to be administered to Rh-negative patients for preventing Rh disease.

  6. Membrane tenting: separation of the chorioamniotic membrane from the anterior uterine wall during needle insertion. The membranes are carried forward by the needle, but without penetrating them.

  7. MMP-8 PTD Check: a sensitive and specific test for the identification of intraamniotic infection and inflammation. This test is similar to a rapid pregnancy test; it requires a very small amount of amniotic fluid and no laboratory equipment; and the results are available within 15 minutes. The MMP-8 PTD Check is easy to use; it needs low maintenance, and is strongly correlated with standard laboratory procedures.

  8. Polymerase chain reaction (PCR): sensitive and specific qualitative and quantitative technique used in molecular microbiology and other fields that allows amplification of a single or a few copies of a DNA fragment, generating several copies of that DNA piece.

  9. Sonographically guided amniocentesis: refers to the use of ultrasound for selecting the site of needle insertion before amniocentesis. At the time of puncture, the needle is inserted blindly into the amniotic cavity.

  10. Sonographically monitored amniocentesis: refers to the continuous use of ultrasound throughout the procedure. Needle insertion into the amniotic cavity and fetal movements are under constant observation.

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HISTORICAL ASPECTS

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Amniocentesis is the oldest invasive procedure for prenatal diagnosis. It has been in use for more than 100 years, being first employed in the 19th century for the treatment of polyhydramnios.1,2, and 3 Subsequently, amniocentesis was used to perform procedures such as amniography4 and elective terminations of pregnancy,5,6 and it gained popularity in ...

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