OC08.06: Lower uterine segment thickness to predict uterine rupture: a secondary analysis of the PRISMA randomised trial
Bibliographic record
Abstract
To estimate the role of lower uterine segment thickness (LUST) to predict uterine rupture during trial of labour after Caesarean (TOLAC). We performed a secondary analysis of PRISMA randomised trial including women who underwent ultrasound LUST measurement at 34-38 weeks. According to protocol, women were informed about their risk of uterine rupture using LUST (≥2.5 mm: low risk; 2.0-2.4 mm: moderate risk; <2.0 mm: high-risk) and special measures (Caesarean, avoiding dystocia) were used accordingly. The diagnosis of uterine rupture was verified by 3 independent MFM blinded to the LUST. ROC curves with area under the curve (AUC) were used to compare the sensitivity and specificity of LUST to predict uterine rupture in the low-risk group according to ultrasound approach (abdominal, transvaginal, both). Among 3460 eligible participants, 1595 (46%) underwent TOLAC. TOLAC rate were 49% (1382/2809), 46% (178/385) and 13% (35/266) in the low-risk, moderate- and high-risk groups, respectively (p < 0.001). Four (0.3%) uterine ruptures occurred among 1382 TOLAC in the low-risk group but none in the moderate- (0/178) and high-risk (0/35) groups. LUST was associated with uterine rupture using transabdominal (AUC: 0.83; 95%CI: 0.72-0.93); transvaginal (AUC: 0.86; 95%CI: 0.72-0.99), and both approaches (AUC: 0.90; 95%CI: 0.81-0.98; p < 0.001) (all p < 0.001); with different threshold to reach sensitivity of 100% (3.5 mm, 3.5 mm, and 2.9 mm, for specificities of 72%, 62% and 73%, respectively). All cases occurred among women with LUST <3.0mm using the combined approach (4/387 or 1.0%) compared to none among 995 TOLAC with LUST ≥3.0mm (p = 0.01). Third trimester LUST is highly associated with the risk of uterine rupture, and the best approach is a combination of vaginal and abdominal ultrasound. A LUST below 3.0mm should be considered a risk factor for uterine rupture during TOLAC. No uterine rupture was observed among high-risk women who attempted TOLAC after being advised of their risk based on LUST measurement.
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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 | 0.007 | 0.014 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.006 | 0.006 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.005 |
| Insufficient payload (model declined to judge) | 0.010 | 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".