and Marcelo Zugaib4
São Paulo University, Bauru, Brazil
Parisian University, Bauru, France
Member of International Fetal Medicine and Surgery Society, Bauru, Brazil
Obstetrics, University of São Paulo, Bauru, Brazil
Until recently, most of the invasive procedures for fetal karyotyping were indicated in cases of advanced maternal age. Nowadays, abnormal ultrasound findings and a positive test in NIPT (fetal DNA in maternal blood) are rising as indicators for fetal sampling. Genetic diseases are also an indication for invasive procedures and their prenatal diagnosis becoming increasingly frequent.
Abnormalities diagnosed in ultrasound are also an indication for fetal cytogenetic analysis, the most striking examples being increased nuchal translucency or fetal structural abnormalities.
Invasive procedures may also be indicated for fetal therapy. This chapter focuses mainly on diagnostic procedures that are in most common use.
The use of ultrasound for invasive procedures is very important because of its use as a continuous guide. Ultrasound guiding ensures more security to the procedure and decreases the procedure time. The first stage (and almost the longest) of the whole procedure is the search for the best place to carry out the invasive procedure (needle puncture).
18.1 Chorionic Villus Sampling
Chorionic villus sampling (CVS) consists of obtaining villus samplings from the chorion frondosum. The main indications are fetal cytogenetic analysis (karyotype) and a search for genetic diseases through the use of biological techniques. The ideal period for its realization is between 11 and 14 weeks of pregnancy. Before 11 weeks, there is a risk of micrognathia and limb abnormalities and, after 12 weeks, the advantage of the CVS, which is the precociousness of the procedure, is lost. We prefer to perform the CVS at 11 weeks.
Cross-section of the ovum cavity at 16 weeks, showing amniotic fluid sampling guided by ultrasound. The white arrow indicates the needle tip. Note that the cross-section passes by transverse section of the fetal chest (T)
Amniotic fluid sampling (amniocentesis) at 15 weeks of pregnancy. Note that the needle tip (arrow) is refractional in the amniotic fluid and free of fetal parts. Note that the placenta is posterior
Transplacental amniocentesis at 16 weeks’ pregnancy. Arrow: needle’s tip in amniotic fluid (LA). P placenta
Transplacental amniocentesis: needle’s path (arrows) through the placenta (P) with its tip in the amniotic sac (LA) free of fetal parts
Precocious amniocentesis (at 13 weeks) guided by ultrasound: the refractional needle tip (arrow) in the little amniotic sac (LA). P = placenta
Chorionic villus sampling guided by ultrasound: the needle’s path and tip (arrow) inside the trophoblast (T)
Chorionic villus sampling at 10 weeks and 6 days: the hyperechogenic image of the needle tip (arrow) inside the anterior trophoblast (T). AF = amniotic fluid
Chorionic villus sampling guided by ultrasound: the needle’s path (arrow) inside the anterior trophoblast (T)
Ultrasound image of a chorionic villus sampling: the needle’s path (arrow) up to the lateral posterior right trophoblast (T)
Temporal sequence from the insertion of the needle until the trophoblast. Insertion of the needle with its tip (arrow) before reaching the mother’s peritoneum (P). The lateral posterior trophoblast (TROFOBLASTO) is the target
The needle tip (arrow) is now inside the myometrium immediately before the trophoblast. LA = amniotic fluid, VC = trophoblast
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