Uptake of invasive prenatal diagnostic tests in women after detection of soft markers for chromosomal abnormality on ultrasonographic evaluation

Abstract

Objective: Use of soft ultrasonographic markers during routine prenatal ultrasonography (USG) may be used for the screening of aneuploidy in the low-risk population. The aim of this study was to evaluate the acceptance of an invasive test for prenatal diagnosis and to assess the role of various factors in the decision-making regarding an invasive test when confronted with risk for aneuploidy after a soft marker is detected on routine antenatal ultrasonogram.

Study design: Women were referred for USG in our department by primary obstetricians for indications such as a previous child with a congenital malformation, genetic disorder, stillbirth or in women with recurrent spontaneous abortions. Some of the women were referred after prenatal detection of a soft marker on USG. They were screened for soft markers associated with chromosomal abnormality. They were counseled regarding the age-specific risk and the risk of aneuploidy after detection of a marker in comparison to the general population's risk of Down's syndrome. They were also counseled regarding the risk of a procedure-related abortion (0.5%) following an invasive procedure before their decision regarding the use of amniocentesis was made.

Result: Twenty women out of 50 (40%) opted for amniocentesis. Except in one case of trisomy 21 in a fetus with short femur and humerus, all others had normal karyotype. The uptake of the test was comparable between primigravida (33%), women with poor obstetric history (46%) and women with at least one normal live child (45%). There was no statistical difference in the uptake of invasive test based on gestational age as well. Uptake of amniocentesis was higher (78%) in cases with nuchal thickening as compared to other markers (35%).

Conclusion: Ultrasonographic detection of soft markers is associated with a high frequency of uptake for invasive prenatal testing. Increased nuchal thickening is associated with a higher acceptance of amniocentesis. Maternal age, gestational age or previous obstetric history were not associated with the decision to undergo amniocentesis.