Only diagnostic testing removes residual risk for aneuploidy detection. 8 Although a range of positive likelihood ratios (LRs) for a particular aneuploidy exists for each soft marker, even when the highest positive LRs are applied to a population that has previously had a negative cfDNA result, the risk of trisomy 21 is negligibly affected. The detection rates for aneuploidy with commonly employed serum screening strategies (ie, first-trimester screen, integrated screen, sequential screen, contingent screen, or quad screen) are high.ĬfDNA is the single best screening test for the common trisomies (trisomies 21, 18, and 13), and the posttest probability of a common aneuploidy after negative cfDNA screening is very low. However, the relative importance of this approach has evolved rapidly with improved prenatal screening techniques. Traditionally, the presence or absence of specific soft markers was used to modify the probability of trisomy 21 and 18 for high-risk patients. If an isolated soft marker is confirmed, subsequent evaluation and counseling depend on prior aneuploidy screening results, additional risk factors for aneuploidy, and associations with nonaneuploid conditions. In the case of multiple soft markers or structural abnormalities, the approach to evaluation should be individualized. The decision to perform a detailed examination should be made through a shared decision-making framework.
#Ultrasound screen marker code#
Identification of a soft marker is an indication for a detailed obstetrical ultrasound examination (Current Procedural Terminology code 76811) to ensure the finding is isolated. “Isolated” is a soft marker that has been identified in the absence of any fetal structural anomaly, growth restriction, or additional soft marker, following a detailed obstetrical ultrasound examination. 6 Q| What is the initial approach when an isolated soft marker is identified? Given the high sensitivity and specificity of cfDNA for trisomies 21, 18, and 13 across all age groups, in 2020, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine endorsed the option of cfDNA screening for all patients. 5,6 The introduction of cell-free DNA (cfDNA) techniques greatly improved the ability to screen for common aneuploidies. Commonly identified soft markers include echogenic intracardiac focus echogenic bowel choroid plexus cyst(s) single umbilical artery urinary tract dilation shortened humerus, femur, or both thickened nuchal fold and absent or hypoplastic nasal bone 1-4 (Table 1).Ĭontemporaneously with the advancement in aneuploidy detection with soft markers was the development of improved serum screening methods to predict aneuploidy risk. These may be normal variants but are noteworthy because of their association with an increased aneuploidy risk. Soft markers are minor ultrasound findings identified in the midtrimester that commonly do not represent a structural abnormality.
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