Sonographic lower uterine segment thickness after prior cesarean section to predict uterine rupture: A systematic review and meta‐analysis
Bibliographic record
Abstract
INTRODUCTION: Cesarean section rates are increasing with a decrease in the rate of trial of labor after cesarean section. The objective of this study was to systematically review the predictive characteristics of sonographic measurement of lower uterine segment thickness for uterine rupture during labor. MATERIAL AND METHODS: The review was carried out in agreement with PRISMA and SEDATE guidelines. MEDLINE, EMBASE, ClinicalTrials.gov and Cochrane Library were searched from 1990 until November 2018. Quality of included studies was assessed using the QUADAS-2 tool. Data were extracted to construct 2 × 2 tables from each study comparing ultrasound measurement with uterine defect at time of delivery. The data were plotted as a summary receiver-operating characteristic (SROC) curve using the hierarchical SROC model. RESULTS: Twenty-eight observational cohort studies met the selection criteria for inclusion. Sonographic lower uterine segment thickness was measured at a gestational age of 36-40 weeks in women with a previous cesarean section. The risk of bias and concerns regarding applicability were low among most studies. The sonographic measurement was correlated with either delivery outcome or lower uterine segment thickness at the time of repeat cesarean section. The cut-off value for lower uterine segment thickness ranged from 1.5 to 4.05 mm across all studies. An association between thin lower uterine segment measurement and uterine dehiscence and uterine rupture was shown in 27 and four studies, respectively. Nineteen studies were included in a meta-analysis with a subgroup analysis by ultrasound methodology. In the subgroup using the ultrasound methodology associated with uterine rupture, the cut-off value is more precise (2.0-3.65 mm) among these 12 studies. There were 18 cases (1.0%) of uterine rupture, 120 (6.6%) of uterine dehiscence and 1674 (92.4%) women with no uterine defect. The SROC curve showed a sensitivity of 0.88 (95% CI 0.83-0.92) and specificity of 0.77 (95% CI 0.70-0.83). The negative likelihood ratio was 0.11 (95% CI 0.08-0.16) and the diagnostic odds ratio was 34.0 (95% CI 18.2-63.5). CONCLUSIONS: Lower uterine segment thickness >3.65 mm, measured using a standardized ultrasound technique, is associated with a lower likelihood of uterine rupture.
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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 | 0.010 | 0.029 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.028 |
| Bibliometrics | 0.006 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 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".