OC06.02: Impact of an early detailed ultrasound following a high‐risk cell‐free DNA: a systematic review and meta‐analysis
Bibliographic record
Abstract
To systematically examine the performance of a detailed ultrasound (US) performed within 14 weeks, following a high-risk cell-free DNA (cfDNA) for trisomy 21 (T21), 18 (T18) and 13 (T13). PubMed, EMBASE and CINHAL were searched up to February 2024. Singleton pregnancies with high chance of T21, T18 and T13 were included. The index test was a detailed US performed within 14 weeks, when either chorionic villus sampling (CVS) or amniocentesis (AC) can be offered. Prenatal or postnatal karyotype was the reference standard. Risk of bias was assessed using QUADAS-2. Data were extracted to fill 2×2 tables on RevMan5. Fixed-effect inverse variance with 95% confidence interval (CI) was performed on OpenMeta and sROC curves were obtained. Six studies reporting on 691 early thorough scans after high-risk cfDNA for T21, T18 and T13 were included. Abnormal US following a high chance of T21 had a pooled sensitivity, specificity and positive likelihood ratio (PLR) of 75.2% (95% CI, 70.5-79.3%), 87.1% (95% CI, 65.5-96.0%) and 4.27% (95% CI, 1.59%-11.4%), respectively. After a high-risk cfDNA for T13 or T18, the pooled sensitivity was 83.8%(95% CI, 77.4-88.6%), the pooled specificity 90.5% (95% CI, 79.3-96.0%) and the PLR 6.15% (95% CI, 2.92%-12.9%). Risk of bias was high for the index test, being unblinded to the cfDNA results. An early detailed US showed a higher sensitivity, specificity and PLR in fetuses at high risk for T13/T18, corroborating the use of CVS or AC in case of abnormal and normal scans, respectively. Conversely, the US performance was suboptimal in discerning false positive T21 cases within 14 weeks. Given the low rate of mosaic Down syndrome and the availability of established laboratory checklists avoiding unreliable results from villus sampling, CVS remains a reasonable confirmative procedure after a high-risk cfDNA for T21, irrespective of US findings. Nevertheless, future prospective studies with unblinded clinicians to cfDNA results are needed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.009 | 0.029 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.030 |
| Bibliometrics | 0.006 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".