P17At what gestational age can the corpus callosum and cavum septi pellucidi be regularly seen at routine obstetrical ultrasound examination?
Bibliographic record
Abstract
Background Agenesis of the corpus callosum (ACC) is reported to be difficult to detect before 22 weeks gestation. However, the cavum septi pellucidi (CSP) develops with the CC and is seen by 15–16 weeks. Thus, ACC should be detectable by 16 weeks. Purpose To determine at what gestational age the cavum septi pellucidi and corpus callosum become regularly visible and hence ACC can be suspected if they are not visible. Methods Fifty consecutive women referred for US for all indications between 25 June and 9 July 1999 were scanned trans‐abdominally with specific attempt to see the cavum septi pellucidi (CSP) and the corpus callosum. Results BPD ranged from 32 (15.6 week) to 81 mm (33.1 week). The CSP was visible in every fetus starting at BPD 34 mm (16.2 week). On mid sagittal views the CC was also visible starting at BPD 34 mm (16.2 week) in all but 3 fetuses due to fetal position. The CC was seen well enough to confidently measure its length in 27/49 (55%). Conclusions At routine examination, the CSP was detectable by 16.2 week (BPD 34 mm) gestation and in every pregnancy after this age. Using only trans‐abdominal scans, the CC was visible on sagittal views by exploiting access provided by sutures and fontanelles. Detection of complete agenesis of the corpus callosum should be possible by 16 weeks gestation.
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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 | 0.000 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".