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 Tension Versus Tension- Free Foley Balloon for Cervical Ripening (NCT05404776), a randomized na study. The primary outcome is Time to Vaginal Delivery.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05404776 |
| Phase | NA |
| Condition | Induced Vaginal Delivery |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 279 |
| Arms in the primary outcome | n/a |
| Lead sponsor | The University of Texas Medical Branch, Galveston |
| Results posted | Yes |
2. Clinical Question
Population
Nulliparous women undergoing induction of labor. The registry record lists induced vaginal delivery as the condition and describes transcervical Foley balloon placement for cervical ripening.
Intervention
Foley balloon placement with tension: the tubing is pulled to create tension and taped to the patient’s inner thigh.
Comparator
Foley balloon placement without tension, also described as tension-free: the tubing is left free of tension and hangs freely.
Primary question
Does the time from initial Foley balloon placement to vaginal delivery differ between the tension and tension-free approaches? The registry record does not report a comparative estimate or test for this outcome.
The trial focuses on a procedural contrast: the same mechanical cervical-ripening approach is used, while the handling of the balloon tubing differs. Its stated hypothesis is that applying tension results in a shorter time to vaginal delivery than leaving the tubing tension-free. That hypothesis is a question to be tested, not a reported finding.
Other outcomes listed include requests for analgesia following balloon placement, primary cesarean delivery, and chorioamnionitis. Those outcomes can describe additional aspects of the study, but the record does not report their comparative results. It also does not report details such as eligibility criteria beyond the description of nulliparous women undergoing induction, or how participants were recruited. Those details are not reported in the registry record.
3. Trial Design
The registry record identifies a randomized, parallel-group trial with no masking. It describes the study as cluster randomized, and cautions that a simple individual-level re-analysis would be misleading; only the sponsor’s own analysis is shown. The record does not explain what formed a cluster, how clusters were assigned, how many clusters were included, or how clustering was handled in the sponsor’s analysis. Those design details are not reported in the registry record.
The comparison assigned participants to Foley balloon placement with tension or without tension. In the tension group, tubing was pulled and taped to the patient’s inner thigh. In the tension-free group, tubing was left to hang freely. The planned primary measure was time from initial Foley balloon placement to vaginal delivery, expressed in minutes, with the stated timeframe extending up to 24 hours. The registry describes the endpoint using the median and full range.
The record lists enrollment of 279 and a completed status. The study start date is 2022-06-03, and the primary completion date is 2023-06-21. The phase is listed as NA. The sponsor is The University of Texas Medical Branch, Galveston. These are record-level descriptors; they do not establish how many participants contributed data to each outcome or how the analysis population was defined.
No primary outcome analysis is reported in the registry record. The record lists zero analyses, so it does not give a group-specific median, range, treatment contrast, confidence interval, or hypothesis-test result for time to vaginal delivery. It also does not report a statistical analysis plan or enough cluster-level information to independently assess the trial’s analysis.
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.
Before assignment: The intervention is assigned at the cluster (weekly) level; the total number of participants enrolled will be reported as a single total and not separated by clusters.
Overall Study
| Stage | Without Tension (Tension Free) | Tension |
|---|---|---|
| STARTED | 141 | 138 |
| COMPLETED | 141 | 138 |
| NOT COMPLETED | 0 | 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.
| Characteristic | Unit | Without Tension (Tension Free) | Tension | Total |
|---|---|---|---|---|
| Participants analysed | 141 | 138 | 279 | |
| Age, Continuous | years | 23 (18 to 39) | 22 (18 to 42) | 22 (18 to 42) |
| Sex: Female, Male: Female | Participants | 141 | 138 | 279 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 94 | 88 | 182 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 47 | 50 | 97 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 2 | 1 | 3 |
| Race (NIH/OMB): Asian | Participants | 4 | 0 | 4 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 20 | 14 | 34 |
| Race (NIH/OMB): White | Participants | 115 | 122 | 237 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 1 | 1 |
| Region of Enrollment: United States | Participants | 141 | 138 | 279 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Vaginal Delivery, measured over Foley bulb placement to vaginal delivery, up to 24 Hours.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | minutes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is time to vaginal delivery, measured in minutes from the initial Foley balloon placement to delivery. The stated timeframe is placement to vaginal delivery, up to 24 hours. This endpoint captures how long it takes to reach vaginal delivery after the cervical-ripening balloon is placed, rather than measuring only a change in cervical status or the duration of balloon placement itself.
Time-to-event outcomes are useful when the timing of an event matters and when participants may experience that event at different times. In this trial, the event of interest is vaginal delivery, and the recorded starting point is initial balloon placement. A summary such as the median describes the time by which half of the observed times are at or below that value, when the median can be estimated. The full range describes the lowest and highest observed times, but does not show how observations are distributed between those endpoints.
These are general interpretations of the stated summary measures. The registry record does not report the group-specific median or range, the number of participants contributing to the endpoint, or the method used to handle participants who did not have a vaginal delivery within the stated timeframe. It therefore does not permit assessment of the observed timing or of how incomplete follow-up or other endpoint circumstances were treated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of two ways of positioning a Foley balloon during cervical ripening: with tension and without tension. It states the hypothesis that tension would shorten time to vaginal delivery. However, it does not report the primary outcome results or a statistical comparison between groups. There is therefore no posted estimate of the difference in timing, no confidence interval describing its precision, and no p-value indicating the result of a statistical test.
Without those results, the stated hypothesis cannot be judged against the trial’s observed primary outcome. The completed status and enrollment count describe the trial’s progress, not its comparative effect. Likewise, the registered outcome definition tells readers what was intended to be measured, but it does not reveal the times observed in either group.
The record’s design note is important to interpretation. It identifies the study as cluster randomized and cautions that an individual-level re-analysis would be misleading. In cluster-randomized studies, outcomes within the same cluster can be more alike than outcomes from different clusters. General statistical reasoning therefore calls for an analysis that accounts for the assignment and correlation structure. The record does not report the cluster definition, cluster count, or sponsor’s analysis details, so readers cannot evaluate whether or how those features were incorporated.
The registry lists 279 enrolled participants and describes the study as completed, but those details do not establish the number analyzed for the primary endpoint. The registry record does not report analysis populations, participant flow, missing primary outcome data, or reasons for any exclusions. Nor does it state whether the endpoint analysis followed the assigned groups or used another population definition.
Safety figures are reported separately: the registry lists no serious or other adverse events and no deaths in either group, alongside the group-specific counts at risk. These entries should be read as the posted registry figures, not as a complete account of all possible harms or a comparison with uncertainty quantified. The record does not report detailed event definitions, collection procedures, or follow-up completeness.
Accordingly, the posted record supports a description of the study question, design features, endpoint, and listed adverse-event counts, but it does not support a conclusion about the comparative primary outcome. Lack of a reported result is not evidence that the approaches produced the same timing. It means the relevant estimate and its precision are not reported in the registry record.
9. Statistical Methods Explained
What does the endpoint summary mean?
The planned primary endpoint is time from initial Foley balloon placement to vaginal delivery, measured in minutes. The registry specifies a median and full range. In general, the median is a measure of the center of observed values: it is the point at which half the observations are at or below it and half are at or above it, subject to the conventions used when there is an even number of observations. The range gives the lowest and highest observed values. It does not describe how densely observations fall near the middle or whether there are groups of unusually short or long times.
For time-to-event outcomes, the timing and occurrence of the event both matter. General methods may account for participants whose event time is not observed during follow-up, for example by treating their follow-up as incomplete rather than assigning an unobserved event time. The registry record does not report whether such participants occurred or how any such cases were handled. It also does not give endpoint results, so the meaning of any group-level median or range cannot be assessed from the registry record.
Why does the cluster-randomized description matter?
The registry identifies the trial as cluster randomized and specifically cautions that a simple individual-level re-analysis would be misleading. In general, a cluster-randomized design assigns groups rather than treating every participant’s assignment as independent. Participants within the same group may share circumstances and have correlated outcomes. If an analysis ignores that dependence, it can treat the data as containing more independent information than they actually do, affecting uncertainty estimates and statistical tests.
Appropriate methods depend on design details, including what constitutes a cluster, how many clusters were assigned, and whether the analysis accounts for cluster-level variation. The record does not report those details or describe the sponsor’s own analysis. Thus, the design note gives a reason not to reconstruct a conventional individual-level comparison, but the available information is insufficient to evaluate the analysis method itself. No independent re-analysis is warranted from the registry summaries.
What can a confidence interval tell readers?
In general, a confidence interval is a range of estimates compatible with the data and the method used to calculate it. Its width conveys precision: a wider interval indicates greater uncertainty about the estimated effect, while a narrower interval indicates greater precision under the assumptions of the analysis. An interval can also show whether effects of different practical sizes remain plausible. It does not make the underlying design or measurement limitations disappear.
No confidence interval for the primary comparison is reported in the registry record. No group-specific primary outcome summaries are reported either. Readers therefore cannot assess the estimated contrast, the uncertainty around it, or whether the data are compatible with a range of possible differences.
What do the planning assumptions describe?
The record describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning illustrations, not observed power and not evidence that the study was designed with those assumptions. The record does not report the trial’s own sample-size justification. No illustration values or observed primary effect are reported in the registry record, so the planning calculations cannot be interpreted numerically from the record.
In general, a planning calculation asks how much information might be needed to detect an assumed effect under specified statistical assumptions. Its answer depends on those assumptions and does not determine the probability that a particular completed trial has demonstrated an effect. A calculation based on an observed effect is especially distinct from prospective design justification: it uses an effect estimate as an input for illustration, and does not replace an analysis of the trial data or quantify the observed result’s reliability.
Why is the analysis description incomplete?
The registry lists zero analyses. It does not state a statistical model, a method for estimating the primary comparison, an adjustment strategy, or a rule for handling missing outcomes. It also does not report whether analyses were specified before examining the data. These details are not reported in the registry record. General statistical principles can explain why they matter, but cannot identify which method the sponsor used or whether it was appropriate.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint, time to vaginal delivery, and several secondary outcomes: requests for analgesia following balloon placement, primary cesarean delivery, and chorioamnionitis. Multiple outcomes create a multiplicity question because conducting or interpreting several statistical tests can increase the chance of a false-positive finding if no adjustment or prespecified hierarchy is used. In general, analysis plans may address this by defining a primary outcome, setting a testing order, or adjusting inference across a family of comparisons. The registry record does not report a multiplicity strategy, outcome hierarchy beyond identifying the primary endpoint, or results for the secondary outcomes.
Missing-data handling is also not reported. The record does not state how many participants had an observed primary endpoint, whether any values were missing, why data might have been unavailable, or how missing observations were treated. For a time-to-event endpoint, the treatment of participants whose vaginal delivery was not observed within the stated timeframe can affect the analysis. The record does not describe that handling.
The analysis population is not reported. The enrollment count does not specify the number analyzed, whether participants were analyzed according to assigned group, or whether any exclusions occurred. The registry’s cluster-randomized design note further means that the analysis population and method need to be understood alongside cluster assignment and dependence. The cluster definition and handling are not reported in the registry record.
These omissions do not establish that the trial lacked an analysis plan or that data were missing. They mean these matters cannot be assessed from the registry record. With no primary or secondary analyses reported, readers cannot evaluate multiplicity-adjusted inference, missing-data sensitivity, or consistency across analysis populations.
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 |
|---|---|---|---|
| Without Tension (Tension Free) | 0 | 141 | 0.0% |
| Tension | 0 | 138 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Without Tension (Tension Free) | 0 of 141 |
| Tension | 0 of 138 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Without Tension (Tension Free) | 0 of 141 |
| Tension | 0 of 138 |
The registry lists adverse-event figures separately for the two study groups. For the tension-free group, 141 participants are listed at risk for serious events and 141 for other events; the listed counts affected are 0 for each. For the tension group, 138 participants are listed at risk for serious events and 138 for other events; the listed counts affected are 0 for each. Deaths are listed as 0 in both groups.
These entries describe what the registry reports, not a complete evaluation of safety. A zero listed count means no events are recorded in that category in these entries; it does not establish that every possible event was actively sought, that all follow-up was complete, or that event reporting was identical between groups. The record does not give detailed definitions, severity criteria, ascertainment procedures, timing, or follow-up completeness for these figures. It also does not provide a statistical comparison or uncertainty interval for adverse events.
Accordingly, the counts should be read as descriptive registry entries. They do not establish equivalence between groups or rule out uncommon events. The record does not report further safety interpretation by the sponsor.
12. What the Result Does, and Does Not, Mean
The record identifies a clinically specific procedural question: whether placing a Foley balloon under tension rather than leaving it tension-free changes the time from placement to vaginal delivery among nulliparous women undergoing induction of labor. It also documents the planned outcome, the two placement approaches, and a cluster-randomized design. Those details clarify what the study was intended to compare.
The record does not report the primary outcome result. It gives no group-specific time summaries, estimated comparison, confidence interval, or test result. Consequently, it does not show whether the observed times differed, how large any difference was, or how precisely it could be estimated. It also cannot establish that the groups had the same outcome. An unreported estimate is not a finding of no difference.
The record lists 279 enrolled participants and a completed status, but enrollment alone does not show how many contributed primary outcome data or how participants were analyzed. The cluster-randomized design matters because the appropriate uncertainty calculation depends on the allocation structure and the analysis method. The record cautions against a simple individual-level re-analysis but does not provide enough cluster information to independently examine the sponsor’s analysis.
Zero serious events, other events, and deaths are listed for both groups in the adverse-event entries. These are descriptive counts, not proof that the methods have identical safety profiles or that no events could occur. Details needed to interpret ascertainment and follow-up are not reported in the registry record.
In practical statistical terms, this record establishes the question and some design and safety descriptors, but not the comparative evidence needed to evaluate the primary hypothesis. The distinction is between a trial being registered as completed and its outcome estimates being available in the registry. Readers need the sponsor’s analysis and sufficient methods information to judge the result and its precision.
13. Why This Trial Matters Statistically
This trial addresses a focused question about how a mechanical cervical-ripening procedure is performed. Comparing tension with a tension-free placement makes the contrast concrete, while the chosen endpoint emphasizes timing from balloon placement to vaginal delivery. From a statistical perspective, the value of such a comparison depends not only on the outcome definition but also on randomization, analysis, and clear reporting of estimates and uncertainty.
The cluster-randomized description makes the design especially important to interpretation. Outcomes from people within the same cluster may be related, so the allocation structure must be reflected in the analysis. The record explicitly warns that an individual-level re-analysis would be misleading. Because cluster definitions and analysis details are not reported, readers cannot independently judge how the design informed the sponsor’s result.
The record also illustrates why trial status and enrollment are not substitutes for outcome reporting. A completed study with a stated endpoint does not, by itself, establish the direction, size, or precision of a comparison. Here the primary outcome analysis is not reported in the registry record, which prevents readers from evaluating the stated hypothesis using the registry entry alone.
Finally, the listed adverse-event counts are most useful when read alongside clear definitions, collection methods, and follow-up information. Those details are not reported. The statistical importance of this study therefore lies both in its narrowly specified comparison and in the need for transparent reporting of cluster-aware estimates, uncertainty, analysis populations, and outcome completeness.
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.
A central limitation of the registry record is that it does not report the primary outcome results. No group-specific median or full range is available for time to vaginal delivery, and no comparative estimate or measure of uncertainty is reported. The registered outcome and stated hypothesis therefore cannot be compared with an observed result in this record.
The cluster-randomized design is identified, but important details are absent. The record does not report what defined a cluster, how many clusters were randomized, how randomization was conducted, or how the analysis accounted for clustering. It cautions against a simple individual-level re-analysis, which limits what can be reconstructed independently from the record.
Enrollment is reported, but the analysis population and participant flow are not. The record does not report how many participants contributed to the primary endpoint, how missing or incomplete outcome data were handled, or whether all enrolled participants were analyzed according to assigned group. The up-to-24-hour timeframe is stated, but the treatment of participants without an observed vaginal delivery in that timeframe is not described.
The registry also does not report the trial’s sample-size justification, a statistical analysis plan, a multiplicity strategy, or detailed results for the secondary outcomes. Planning illustrations are described as based on the observed effect, but the numerical illustrations and observed effect are not reported in the registry record. The adverse-event entries lack detailed definitions and ascertainment information. These gaps restrict independent assessment of the comparative estimates and their precision.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Tension Versus Tension- Free Foley Balloon for Cervical Ripening — NCT05404776.
- Registry record last updated 2025-08-06; status last verified 2025-07.
- Results first posted 2025-08-06.
- 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 record describes a completed, randomized, parallel-group, unmasked, cluster-randomized trial sponsored by The University of Texas Medical Branch, Galveston. It lists enrollment of 279, a start date of 2022-06-03, and a primary completion date of 2023-06-21. The study compares transcervical Foley balloon placement with tension against placement without tension in nulliparous women undergoing induction of labor.
The primary endpoint is time to vaginal delivery, measured in minutes from initial balloon placement, with a stated timeframe up to 24 hours and a median and full-range summary. The record states the hypothesis that tension may shorten this time. It does not report a primary outcome analysis, comparative estimate, or confidence interval. Secondary outcomes are listed, but their results are not reported in the registry record.
Adverse-event entries list zero serious events, other events, and deaths in both groups. The registry cautions that a simple individual-level re-analysis would be misleading because the study is cluster randomized. Details of the clusters, statistical analysis, missing data, and analysis populations are not reported in the registry record.