Beyond Trisomy 21: Additional Chromosomal Anomalies Detected through Routine Aneuploidy Screening

Abstract

Prenatal screening is often misconstrued by patients as screening for trisomy 21 alone; however, other chromosomal anomalies are often detected. This study aimed to systematically review the literature and use diagnostic meta-analysis to derive pooled detection and false positive rates for aneuploidies other than trisomy 21 with different prenatal screening tests. Non-invasive prenatal testing had the highest detection (DR) and lowest false positive (FPR) rates for trisomy 13 (DR: 90.3%; FPR: 0.2%), trisomy 18 (DR: 98.1%; FPR: 0.2%), and 45,X (DR: 92.2%; FPR: 0.1%); however, most estimates came from high-risk samples. The first trimester combined test also had high DRs for all conditions studied (trisomy 13 DR: 83.1%; FPR: 4.4%; trisomy 18 DR: 91.9%; FPR: 3.5%; 45,X DR: 70.1%; FPR: 5.4%; triploidy DR: 100%; FPR: 6.3%). Second trimester triple screening had the lowest DRs and highest FPRs for all conditions (trisomy 13 DR: 43.9%; FPR: 8.1%; trisomy 18 DR: 70.5%; FPR: 3.3%; 45,X DR: 77.2%; FPR: 9.3%). Prenatal screening tests differ in their ability to accurately detect chromosomal anomalies. Patients should be counseled about the ability of prenatal screening to detect anomalies other than trisomy 21 prior to undergoing screening.

Non-invasive prenatal testing for aneuploidy screening

“…As with all screening tests, the positive predictive value (PPV) of a high-chance result is lower when the prevalence of a condition is lower. This is shown in table 1 with the lower PPVs for trisomies 18 and 13 compared with trisomy 21, and lower PPVs in a general obstetric population compared with a high-chance population 141516. This is an important distinction to make during pre-test counselling, particularly for women in the general obstetric population who choose NIPT for first-line aneuploidy screening.…”

“…This is demonstrated in Table 1 with the lower PPVs for trisomies 18 and 13 compared with trisomy 21 and lower PPVs in a general obstetric population compared with a high-chance population. [23][24][25] This distinction should be clearly explained as part of the pretest counselling process, particularly for women in the general obstetric population who choose NIPT for first line aneuploidy screening. If a woman receives a high-chance or no-call NIPT result and wants a definite diagnosis, she can be offered invasive testing, as discussed above.…”

A first look at women's perspectives on noninvasive prenatal testing to detect sex chromosome aneuploidies and microdeletion syndromes

“…It is critical that information regarding all conditions being evaluated is disclosed before prenatal testing, as the post‐test period is not the time for women to consider an abnormal result and the impact of that information on their pregnancy . It is well accepted that the breadth of information that must be conveyed to support informed decision making for conventional screening tests poses challenges of both time and resources to the clinician–patient encounter.…”

Mapping Publication Trends and Knowledge Structure on Non-Invasive Prenatal Testing – A Bibliometric Analysis

“…The appearance of NIPT enriches the prenatal testing program and greatly reduces many unnecessary invasive tests, such as villus biopsy, amniocentesis and umbilical cord blood puncture. Since NIPT can effectively reduce the abortion rate, it also reduces the anxiety of pregnant women [5] . It brings a great impact on the traditional prenatal examination mode, and has become one of the important technologies in prenatal screening.…”