This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Single or Double-layer Uterine Closure Techniques (NCT03629028), a randomized na study. The primary outcome is Number of Participants With Niche Visualized by Saline Infusion Sonography.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03629028 |
| Phase | NA |
| Condition | Uterine Scar, Cesarean Section Complications, Cesarean Section; Dehiscence |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 282 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Safak Baran Yilmaz |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people undergoing cesarean section. The registry record lists uterine scar and cesarean-related complications among its conditions, but does not report further eligibility criteria or describe the analyzed population in detail. Enrollment was 282.
Intervention
One group received single-layer uterine closure during cesarean. The registry describes follow-up assessment for a niche and measurements that include residual myometrium thickness, adjacent myometrium thickness, and niche dimensions.
Comparator
The comparison group received double-layer uterine closure. The registry describes the same general diagnostic assessments for both groups, including saline infusion sonography for niche presence at 6 to 9 months.
Primary question
The primary endpoint asks how many participants had a niche visualized by saline infusion sonography at 6 to 9 months. The clinical question is whether the recorded frequency of this scar finding differs between the two closure groups. The registry record does not report a group comparison or primary endpoint result, so the direction and precision of any difference cannot be described.
3. Trial Design
The registry identifies this as a randomized, parallel-group trial with no masking. Participants were assigned to single-layer or double-layer uterine closure during cesarean. Enrollment was 282. The listed status is completed, and the registry lists 2018-08-18 as both the study start date and the primary completion date. The reason those dates are the same is not reported in the registry record.
The study focus is the uterine scar defect called a niche. The registry description proposes examining whether closure technique is related to niche development and scar measurements. The primary outcome is the count of participants with a niche visualized by saline infusion sonography at 6 to 9 months. Other listed assessments include residual myometrium thickness at 6 to 9 months and adjacent myometrium thickness; niche dimensions are also described in the arm information.
Random assignment is intended, in general, to make treatment groups comparable at the start of a study, although it does not guarantee balance in every characteristic. The registry does not describe the randomization method, allocation concealment, or procedures used to maintain assignments. Masking is listed as none, but whether sonographers or people interpreting scans were unaware of group assignment is not reported in the registry record.
The record does not state detailed eligibility criteria, the setting, recruitment procedures, or the follow-up schedule beyond the primary endpoint timeframe. It also does not report a protocol, statistical analysis plan, or sample-size justification. The enrollment figure therefore should not be interpreted as evidence about how the original target was chosen.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Single Layer | Double Layer |
|---|---|---|
| STARTED | 141 | 141 |
| COMPLETED | 109 | 116 |
| NOT COMPLETED | 32 | 25 |
Reasons for not completing this period:
| Reason | Single Layer | Double Layer |
|---|---|---|
| Lost to Follow-up | 26 | 23 |
| Pregnancy | 4 | 2 |
| intolerance to examination | 2 | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: same ethnic origin, 18-45 age, who underwent first cesarean operation
| Characteristic | Unit | Single Layer | Double Layer | Total |
|---|---|---|---|---|
| Participants analysed | 109 | 116 | 225 | |
| Age, Continuous | years | 29.8 (SD 4.1) | 30.8 (SD 5.1) | 30.3 (SD 4.7) |
| Sex: Female, Male: Female | Participants | 109 | 116 | 225 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 109 | 116 | 225 |
| Body mass index | kg/m^2 | 28.9 (SD 4.2) | 29.8 (SD 4.6) | 29.3 (SD 4.4) |
| Gestational age at delivery | weeks | 38 (SD 2) | 38.1 (SD 2.1) | 38.1 (SD 2) |
| birth weight | g | 3191.5 (SD 570) | 3261.4 (SD 633) | 3227.3 (SD 602.8) |
| Tobacco use | Participants | 5 | 4 | 9 |
| Diabetes mellitus | Participants | 6 | 9 | 15 |
| Hypertension in pregnancy | Participants | 10 | 9 | 19 |
| History of infertility | Participants | 22 | 25 | 47 |
| Nulliparity | Participants | 103 | 105 | 208 |
| Emergent cesarean section | Participants | 30 | 35 | 65 |
| Contractions before labor | Participants | 29 | 34 | 63 |
| ≥4 cm cervical dilatation | Participants | 11 | 14 | 25 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Niche Visualized by Saline Infusion Sonography, measured over 6 to 9 months.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with a niche visualized by saline infusion sonography at 6 to 9 months. A niche is described in the registry as a defect at the uterine incision line. For this endpoint, each participant is classified according to whether the imaging assessment visualized a niche; the outcome is then expressed as a count of participants with that finding.
This kind of endpoint is used to describe a structural feature of the uterine scar. The registry’s rationale connects closure technique with scar healing and identifies niche presence as an outcome of interest. Related assessments include residual myometrium thickness, adjacent myometrium thickness, and measurements of niche dimensions. These measures describe different aspects of the scar and should not be treated as interchangeable with the primary count.
In general, a count of participants with an event can be compared between randomized groups to assess the observed frequency of that event. Interpretation depends on the group counts, the number assessed in each group, and the uncertainty around the comparison. The primary group counts, effect estimate, and confidence interval are not reported in the registry record. Consequently, the endpoint definition is available, but the size and precision of the primary result cannot be evaluated from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry defines a clinically specific primary endpoint: niche visualization by saline infusion sonography at 6 to 9 months after cesarean closure. It also identifies single-layer and double-layer closure as the randomized comparison. However, the registry record does not report the primary outcome counts by group, an effect estimate, a confidence interval, or a test result. There is therefore no reported primary comparison on which to base a statistical interpretation of the relative frequency of niche visualization.
This absence of a reported result is different from a finding of no difference. Without the group results, it is not possible to tell whether the observed counts were similar or different, or whether the data were precise enough to distinguish a meaningful difference from random variation. A confidence interval, in general, describes a range of effect sizes compatible with the data under the analysis assumptions. No such interval is reported for the primary endpoint in the registry record.
The enrollment figure is 282, but that total alone does not reveal how many participants contributed an outcome assessment in each group. The adverse-event summaries list 109 participants at risk in the single-layer group and 116 in the double-layer group. Those safety figures are not a substitute for the primary endpoint denominators or outcome counts. The registry does not explain the relationship between enrollment and the participants included in those safety summaries.
The registry lists secondary outcomes involving residual and adjacent myometrium thickness, but it does not report their results in the information available for this analysis. Niche dimensions and symptoms are also described in the arm information; their analysis results and the exact status of those measures are not reported in the registry record. Thus, the record supports describing the intended comparison and measurements, not drawing a conclusion about the scar findings observed in the trial.
Randomization can support a causal comparison when assignment, follow-up, and analysis are appropriately handled. It does not by itself resolve questions about missing outcome data, measurement procedures, or deviations from assigned treatment. Those details, along with the analysis population and statistical methods used for the primary result, are not reported in the registry record. The result should therefore be read as unavailable for statistical interpretation, rather than as evidence for or against either closure technique.
9. Statistical Methods Explained
The study is listed as randomized and parallel-group, with participants assigned to one of two closure approaches. In general, randomization aims to reduce systematic differences between groups at baseline by assigning treatment independently of participant characteristics. Its benefit depends on the assignment process being implemented as intended and on suitable handling of participants after assignment. The registry does not describe the randomization sequence, allocation concealment, or analysis population, so those features cannot be assessed.
What does the primary outcome count?
The primary measure is a binary participant-level finding: whether saline infusion sonography visualized a niche at the incision line at 6 to 9 months. The registry describes the reported quantity as a count of participants with a niche. A group count is informative only when interpreted alongside the number of participants assessed in that group. For a comparison between groups, an effect estimate and its uncertainty help distinguish the observed contrast from the range of contrasts that could plausibly arise through sampling variation. The primary counts and corresponding statistical estimates are not reported in the registry record.
What does no masking imply?
Masking is listed as none. In general, knowledge of group assignment can influence care, follow-up, or outcome assessment, depending on how the study is conducted and how subjective the measurement is. Imaging-based endpoints may still involve judgment in acquiring or interpreting images. The record does not say whether the people performing or interpreting sonography were masked, how niche visualization was defined operationally, or whether assessment procedures were standardized between groups.
How should statistical significance and uncertainty be understood?
In general, a significance test evaluates how compatible the data are with a specified null hypothesis under the assumptions of the chosen method. A p-value is not a measure of the size or clinical importance of an effect. A confidence interval communicates uncertainty about an estimate and can include values representing different possible magnitudes or directions. Neither a p-value nor a confidence interval for the primary comparison is reported in the registry record. The particular test, model, covariate adjustment, and threshold used for the trial’s primary analysis are also not reported.
The registry describes one analysis and notes that the primary outcome has several categories or time points and is not reduced to one comparison in the registered results information. That means the registry record does not present a single primary contrast that can be interpreted. The analysis details explaining the categories or time points, how they were selected, and how the comparison was conducted are not reported.
What do planning assumptions mean?
A planning illustration based on an observed effect is not the same as the trial’s original sample-size justification, and it does not describe observed power. The assumptions stated for the illustration are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. In general, such an illustration asks how many participants per arm might be needed under those assumptions to detect a chosen effect size. The registry record does not report the trial’s own sample-size justification, its intended effect size, or its design assumptions. No planning illustration should be taken as proof that the completed trial had a particular probability of detecting an effect.
Why can over-dispersion matter?
Over-dispersion is a general issue in count models when observed variation exceeds what a selected model assumes. It can lead to uncertainty estimates that are too small if it is ignored. The primary endpoint in this trial is a participant count for a binary finding, not a repeated event count described in the record. No over-dispersion assessment or model choice is reported, and there is no basis for claiming that over-dispersion was present or relevant to the trial analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six outcome measures and names secondary outcomes that include residual myometrium thickness at 6 to 9 months and adjacent myometrium thickness. It also describes niche presence and niche dimensions in the arm information. When a study examines multiple outcomes, time points, or categories, the chance of obtaining at least one apparently notable result can increase if many comparisons are tested. In general, multiplicity procedures can address this issue, but the registry record does not report whether any such procedure was planned or used.
The registry notes that the primary outcome has several categories or time points and is not reduced to one comparison in the registered results information. It does not state which comparison was designated as primary for statistical testing, how the categories or time points were handled, or whether secondary outcomes were treated as confirmatory or exploratory. A single analysis is listed, but that alone does not specify the model or resolve the multiplicity questions.
Missing-data handling is not reported in the registry record. The number of participants enrolled does not establish how many completed imaging or contributed each outcome. The record does not describe withdrawals, exclusions, missing scans, imputation, or sensitivity analyses. The analysis population—such as whether participants were analyzed according to randomized assignment—is also not reported. Without these details, the possibility of bias from missing outcomes or post-randomization exclusions cannot be evaluated.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Single Layer- | 0 | 109 | 0.0% |
| Double Layer | 0 | 116 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Single Layer- | 0 of 109 |
| Double Layer | 0 of 116 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1.1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Single Layer- | 1 of 109 |
| Double Layer | 0 of 116 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Single Layer- | Double Layer |
|---|---|---|---|
| pregnancy occurred after cesarean | Pregnancy, puerperium and perinatal conditions | 1 of 109 | n/a of 116 |
The registry’s adverse-event summary lists serious events separately from other events. For serious events, it records 0 affected participants in the single-layer group and 0 in the double-layer group. The listed numbers at risk are 109 and 116, respectively. Deaths are listed as 0 in both groups.
For other events, the summary lists 1 affected participant in the single-layer group and 0 in the double-layer group. These are counts, not estimates of comparative risk. No rates, confidence intervals, or statistical comparison are reported, and none can be inferred from the counts alone. The record does not provide event descriptions or explain the collection and classification procedures in this summary.
Zero serious events in these summaries means none were recorded in the listed groups; it does not establish that serious events could not occur or that the two approaches have equivalent safety. The safety figures also do not provide a complete account of the trial’s primary scar endpoint.
12. What the Result Does, and Does Not, Mean
The registry record identifies a randomized comparison of single-layer and double-layer uterine closure and specifies niche visualization by saline infusion sonography at 6 to 9 months as the primary outcome. It also outlines additional scar measurements. These details establish what the trial set out to compare and measure.
The primary outcome results are not reported in the registry record. Accordingly, the record does not establish how many participants in either group had a niche visualized, how large any group difference was, or how precisely that difference was estimated. It cannot support a conclusion that either closure approach produced more or fewer niches, or that the approaches were similar.
The same caution applies to the secondary scar measurements: their names and timeframes are listed, but their results are not reported in the registry record. The safety summary records no serious events in either group and lists one other event in the single-layer group and none in the double-layer group. These sparse counts do not by themselves establish comparative safety, and the registry does not provide enough detail to interpret the event types or ascertainment.
In general, trial interpretation depends on the observed results, uncertainty, outcome assessment, and handling of all randomized participants. Randomization is a design feature, not a substitute for outcome reporting. The registry information supports a description of the study question and selected design features, but not an estimate of treatment effect or a conclusion about clinical benefit or harm.
13. Why This Trial Matters Statistically
This trial addresses a statistical question involving a surgical technique and a structural imaging endpoint. Comparing the number of participants with a visualized niche is conceptually different from comparing a continuous scar measurement such as myometrium thickness. The endpoint type determines what information is needed for interpretation: the participant counts, group denominators, and an estimate of the between-group contrast with its uncertainty.
The randomized parallel design is relevant because it aims to make the comparison less vulnerable to baseline confounding. Yet design labels alone do not show whether participants were followed consistently, how imaging was interpreted, or whether all randomized participants were analyzed as assigned. Those details matter especially when the outcome is measured after the procedure and the record lists no masking.
The registry also illustrates why an outcome definition is not the same as an outcome result. It identifies niche visualization at 6 to 9 months as primary, but does not report the group results or a statistical comparison. Without those, readers cannot evaluate the magnitude, direction, or precision of the finding. The listed secondary measurements and adverse-event counts answer different questions and cannot fill that gap.
Statistically, the most important limitation is therefore not a reported estimate with wide uncertainty, but the absence of the primary comparative result in the registry record. Clear outcome reporting would allow readers to assess the observed contrast, the uncertainty around it, and the contribution of missing data and analysis choices. Until then, the trial’s stated question can be described, but its primary statistical answer cannot.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record does not report the primary outcome counts by group, an effect estimate, a confidence interval, or a p-value. This prevents assessment of the direction, magnitude, and precision of the primary comparison. The record indicates that the primary outcome has several categories or time points and is not reduced to one comparison in the registered results information, leaving the intended primary contrast unclear.
Important details about outcome measurement are also absent. The record identifies saline infusion sonography and the 6 to 9 month timeframe, but does not report the operational criteria for niche visualization, assessor training, image quality procedures, or whether scan assessors were masked. Masking is listed as none, while the status of assessor masking is not described.
The record does not report the number of participants with completed primary assessments, participant flow by group, missing-data methods, or the analysis population. It is therefore unclear how the enrollment of 282 relates to participants contributing outcome data. Randomization procedures, allocation concealment, protocol deviations, and statistical-model details are not reported.
Although secondary outcomes and niche measurements are described, their results and the handling of multiple outcomes are not reported. The registry also does not state the trial’s sample-size justification or planned detectable effect. The safety summary gives limited event counts without event descriptions or detailed ascertainment information. These omissions restrict interpretation to the study’s registered question and design, rather than its comparative results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Single or Double-layer Uterine Closure Techniques — NCT03629028.
- Registry record last updated 2020-05-01; status last verified 2020-04.
- Results first posted 2020-05-01.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
The registry describes a completed, randomized, parallel-group study with no masking, comparing single-layer and double-layer uterine closure during cesarean. Enrollment was 282. The listed start and primary completion dates are both 2018-08-18.
The primary endpoint is the number of participants with a niche visualized by saline infusion sonography at 6 to 9 months. Secondary scar assessments include residual myometrium thickness and adjacent myometrium thickness. The registry record does not report the primary outcome comparison or the results of those secondary assessments.
The safety summary lists 0 serious events in each group, with 1 other event in the single-layer group and 0 in the double-layer group. The record does not provide enough information to interpret these counts as a complete comparative safety assessment.