Is Routine Amniocentesis for Advanced Maternal Age Still Indicated?
Bibliographic record
Abstract
OBJECTIVE: To evaluate a policy of selective rather than routine use of amniocentesis for advanced maternal age. METHOD: A consecutive series of 359 pregnant women aged 38-47 underwent nuchal translucency measurement (NTM) at 10-14 weeks, maternal serum screening (MSS) by alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG) at 15-17 weeks, and second trimester ultrasound at 21-23 weeks. Women with NTM <3 mm, MSS-derived risk <1/250, and a normal second trimester sonography were considered at low risk and were suggested not to have an amniocentesis. RESULTS: Either the NTM or MSS test was positive in 130 women; 105 (81%) of them elected to have an amniocentesis, versus 122 (53%) of 229 in whom both tests were negative (p < 0.001). Nineteen (5%) of 359 patients had NTM > or =3 mm; all 7 cases of Down's syndrome were in this group; 122 (34%) of 359 patients had a MSS-derived risk > or =1/250; 6 of the 7 cases of Down's syndrome were in this group: Ten patients had an abnormal second trimester ultrasound, 1 of which had trisomy 18. Of the 219 patients with MSS-derived risk <1/250, a NTM <3 mm, and a normal second trimester ultrasound, none had a baby with a chromosomal abnormality (95% confidence interval: 0-1.4%). CONCLUSION: Amniocentesis may be offered on a selective rather than routine basis in women over 38, based upon the results of noninvasive screening tests.
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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 | 0.005 | 0.037 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".