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CVS is an invasive diagnostic test that can be done during the first trimester of pregnancy for individuals that are looking to identify or are at higher risk of passing chromosomal abnormalities. A tissue cell sample of the placenta is obtained abdominally via needle or via vaginal insertion of a catheter/syringe into the cervix in combination ...
The triple test, also called triple screen, the Kettering test or the Bart's test, is an investigation performed during pregnancy in the second trimester to classify a patient as either high-risk or low-risk for chromosomal abnormalities (and neural tube defects). The term "multiple-marker screening test" is sometimes used instead.
The use of ultrasound and biochemical markers to detect aneuploidies is usually done in the first and / or second trimester of pregnancy. [8] Aneuploidies is when a fetus retains an abnormal amount of haploid cells from their parents. However, both of these approaches have a high rate of false positive results of 2–7%. [9]
Another test that may be performed is a chromosomal microarray, which can detect chromosomal imbalances, such as small- and large-scale deletions and duplications. [8] Chromosomal microarray can be performed on cultured or uncultured fetal tissue, with results available as early as 3 days. [5]
It entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks. [2]
Certain chromosomes carry imprinted genes involved in growth or placental function, which may contribute to impaired pregnancy progress when CPM is detected. [7] Different chromosomes are observed at different frequencies depending on the type of CPM observed. [2] The pregnancy outcome is strongly chromosome specific.
A chromosomal abnormality, chromosomal anomaly, chromosomal aberration, chromosomal mutation, or chromosomal disorder is a missing, extra, or irregular portion of chromosomal DNA. [ 1 ] [ 2 ] These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or ...
As nuchal translucency size increases, the chances of a chromosomal abnormality and mortality increase; 65% of the largest translucencies (>6.5mm) are due to chromosomal abnormality, while fatality is 19% at this size. [2] A nuchal scan may also help confirm both the accuracy of the pregnancy dates and the fetal viability.