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 Fetoscopic Endoluminal Tracheal Occlusion in Severe Left Congenital Diaphragmatic Hernia (NCT02549820), a na na study. The primary outcome is Successful Balloon Placement and Removal..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02549820 |
| Phase | NA |
| Condition | Congenital Diaphragmatic Hernia, Pulmonary Hypoplasia |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 28 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Children's Hospital of Philadelphia |
| Results posted | Yes |
2. Clinical Question
Population
Pregnant women and fetuses with severe left congenital diaphragmatic hernia are the population described. The registry record reports the outcome as maternal/fetal dyads because the procedure takes place prenatally. Further eligibility criteria are not reported in the registry record.
Intervention
Fetoscopic endoluminal tracheal occlusion involves placing a detachable balloon in the fetal airway and removing it after several weeks. The listed devices are the GoldBAL2 Detachable Balloon and BALTACCIBDPE100 Delivery Catheter. Insertion may be attempted up to 3 times.
Comparator
There is no concurrent comparator group. This is a single-group trial, with allocation listed as NA and masking listed as none. The registry record therefore does not describe a randomized comparison with usual care or another intervention.
Primary question
The primary endpoint counts participants with successful balloon placement and removal. It is a procedural measure, not a direct measure of fetal lung growth, survival, or longer-term health. The primary endpoint result is not reported in the registry record.
3. Trial Design
This is a pilot trial of fetoscopic endoluminal tracheal occlusion in severe left congenital diaphragmatic hernia. The registry record describes a single-group design: participants receive the FETO procedure, without a separate control arm. Allocation is listed as NA, masking as none, and phase as NA. These design details mean the record does not describe a randomized or masked comparison.
The intervention uses a detachable balloon placed inside the fetal airway, with the intention of removing it after several weeks. The primary endpoint concerns successful placement and removal, counted per patient. Insertion may be attempted up to 3 times in one pregnant woman or fetus. The maximum stated implantation duration is 7 weeks, while the duration can be shorter if placement occurs later in gestation or removal occurs earlier, electively or emergently.
The registry lists an enrollment of 28 and identifies the status as active, not recruiting. It lists July 2015 as the start and May 1, 2025 as the primary completion date. These registry entries do not by themselves establish how many participants completed the procedure or contributed evaluable endpoint data. Those details are not reported in the registry record.
Secondary outcomes include fetal lung growth due to FETO and survival rate of FETO patients. The registry record lists no analyses. It does not report a statistical analysis plan, a control condition, or a stated method for comparing outcomes. Without a concurrent comparison, the study can describe outcomes among those treated, but cannot isolate the effect of the intervention from other influences.
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: Fourteen maternal/neonatal dyads were enrolled in this study.
Overall Study
| Stage | FETO in CDH - Maternal | FETO in CDH - Fetal/Neonatal |
|---|---|---|
| STARTED | 14 | 14 |
| COMPLETED | 14 | 13 |
| NOT COMPLETED | 0 | 1 |
Reasons for not completing this period:
| Reason | FETO in CDH - Maternal | FETO in CDH - Fetal/Neonatal |
|---|---|---|
| Death | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: This outcome measure is reported as maternal/fetal dyads, as the intervention is performed prenatally.
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 | FETO in CDH |
|---|---|---|
| Participants analysed | 28 | |
| Age, Customized: Number of maternal participants ≥ 18 years of age | Participants | 14 |
| Age, Customized: Age Not Collected (Neonates Only) | Participants | 0 |
| Sex: Female, Male: Sex of maternal participants – Female | Participants | 14 |
| Sex: Female, Male: Sex of maternal participants – Male | Participants | 0 |
| Sex: Female, Male: Sex of fetal/neonatal participants – Female | Participants | 6 |
| Sex: Female, Male: Sex of fetal/neonatal participants – Male | Participants | 8 |
| Race (NIH/OMB): Race of maternal participants – American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Race of maternal participants – Asian | Participants | 0 |
| Race (NIH/OMB): Race of maternal participants – Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Race of maternal participants – Black or African American | Participants | 1 |
| Race (NIH/OMB): Race of maternal participants – White | Participants | 12 |
| Race (NIH/OMB): Race of maternal participants – More than one race | Participants | 1 |
| Race (NIH/OMB): Race of maternal participants – Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): Race of fetal/neonatal participants – American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Race of fetal/neonatal participants – Asian | Participants | 0 |
| Race (NIH/OMB): Race of fetal/neonatal participants – Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Race of fetal/neonatal participants – Black or African American | Participants | 1 |
| Race (NIH/OMB): Race of fetal/neonatal participants – White | Participants | 12 |
| Race (NIH/OMB): Race of fetal/neonatal participants – More than one race | Participants | 1 |
| Race (NIH/OMB): Race of fetal/neonatal participants – Unknown or Not Reported | Participants | 0 |
| Ethnicity (NIH/OMB): Ethnicity of maternal participants – Hispanic or Latino | Participants | 1 |
| Ethnicity (NIH/OMB): Ethnicity of maternal participants – Not Hispanic or Latino | Participants | 13 |
| Ethnicity (NIH/OMB): Ethnicity of maternal participants – Unknown or Not Reported | Participants | 0 |
| Ethnicity (NIH/OMB): Ethnicity of fetal/neonatal participants – Hispanic or Latino | Participants | 2 |
| Ethnicity (NIH/OMB): Ethnicity of fetal/neonatal participants – Not Hispanic or Latino | Participants | 12 |
| Ethnicity (NIH/OMB): Ethnicity of fetal/neonatal participants – Unknown or Not Reported | Participants | 0 |
| Maternal BMI: BMI 20-25 | Participants | 1 |
| Maternal BMI: BMI 25-30 | Participants | 7 |
| Maternal BMI: BMI 30-35 | Participants | 3 |
| Maternal BMI: BMI 35-40 | Participants | 1 |
| Maternal BMI: BMI 40-45 | Participants | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Successful Balloon Placement and Removal., measured over 7 weeks.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is successful balloon placement and removal, counted as participants. It is a procedural endpoint: it asks whether the intended device-placement and removal steps were completed for a patient. The registry record says insertion may be attempted up to 3 times in one pregnant woman or fetus, and reports the outcome as maternal/fetal dyads because the intervention occurs before birth.
The stated timeframe is 7 weeks. This is the maximum duration described for a balloon placed at 27 weeks 0 days and removed in the 34th week. The record also notes that implantation can be shorter if the balloon is placed later or removed earlier, including elective or emergency removal. Thus, the stated timeframe describes a maximum possible implantation period rather than a uniform duration for every participant.
A procedural endpoint is useful for describing whether the central intervention steps were achieved in this pilot study. It does not, on its own, establish the degree of fetal lung growth, survival, or longer-term health. Those are distinct outcomes, and the registry record lists lung growth and survival as secondary outcomes. The primary endpoint result and its statistical analysis are not reported in the registry record. Consequently, the endpoint definition can be explained, but its observed frequency and precision cannot be assessed from the recorded information.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines the primary outcome clearly enough to identify what is intended to be counted: participants with successful balloon placement and removal. However, it does not report the primary endpoint result. There is therefore no posted count or estimate from which to describe how often the procedure met this endpoint, or how precisely that frequency is estimated. The registered enrollment of 28 should not be treated as a reported number of successful procedures or as proof that all enrolled participants contributed to the endpoint.
The study is single-group and unmasked, with no concurrent control group described. Its results, if reported, would characterize outcomes among participants undergoing FETO in this trial. They could not alone show how those outcomes compare with an alternative approach. In a single-group study, observed outcomes may reflect the intervention, the underlying condition, participant selection, care practices, or other factors. Without a comparative design and an analysis addressing those influences, the contribution of the intervention cannot be separated from them.
The registry lists fetal lung growth and survival as secondary outcomes, but the outcome results and analyses are not reported in the registry record. No conclusion about those outcomes can be drawn from their names alone. The same caution applies to the safety figures: the record gives affected counts and selected serious-event terms, but these figures do not establish that the procedure caused the events.
Safety reporting indicates that 28 participants were at risk for serious adverse events and 28 were recorded as affected. For other adverse events, 28 were at risk and 13 were recorded as affected; the record also reports 1 death. Selected serious-event terms are reported with percentages. These are descriptive safety figures in the FETO group, not estimates of excess risk relative to a comparison group. The listed events may represent different clinical experiences and should not be combined into a single measure of benefit or harm.
The registry record lists no analyses. It does not report confidence intervals, hypothesis tests, adjusted estimates, or the handling of missing outcome data. As a result, the available record supports a description of the design, endpoint definition, and safety counts, but not a quantitative conclusion about the primary endpoint or a comparative treatment effect.
9. Statistical Methods Explained
What does a single-group design estimate?
In general, a single-group study describes outcomes among participants who receive the intervention. For a binary outcome, the central descriptive quantity is the proportion of participants who experience the event of interest, such as successful completion of the procedural endpoint. A confidence interval, when reported, communicates the uncertainty around that estimate. It represents a range of values compatible with the observed data under the statistical method used; it is not a guarantee that the underlying value lies within that range.
For this trial, the endpoint is a count of participants with successful balloon placement and removal. The registry record does not report that count, an estimated proportion, or a confidence interval. It also lists no analyses. The endpoint definition alone therefore does not support an estimate of procedural success. The registered enrollment of 28 is not interchangeable with the number having a successful outcome, nor does it establish the number with complete endpoint information.
Why does the lack of a comparator matter?
In general, a comparison group helps distinguish outcomes associated with an intervention from outcomes that might have occurred under another treatment or care pathway. A randomized comparison can also reduce systematic differences between groups, although randomization does not remove every source of uncertainty. Here, the design is single-group and allocation is listed as NA, so no like-for-like control comparison is described.
A result observed in the treated group would be a description of that group, not a direct estimate of the difference between FETO and an alternative. Differences from external populations would be difficult to interpret unless the populations, outcome definitions, follow-up, and care settings were sufficiently comparable. Such a comparison is not reported in the registry record.
How should the endpoint timing be understood?
The registered timeframe is 7 weeks, which is stated as the maximum duration of balloon implantation for the described placement and removal timing. The record explicitly allows shorter durations when placement is later in gestation or removal is earlier. In general, a variable exposure or follow-up interval can affect how outcomes are interpreted: participants may not have the same opportunity or duration to experience an event. The endpoint is successful placement and removal, rather than an event rate per unit of time, and the record does not report individual implantation durations or a time-adjusted analysis.
The procedure may be attempted up to 3 times. This is relevant to the operational meaning of success: the registry describes a patient-level outcome while allowing repeated insertion attempts. It does not report how failed attempts, repeat attempts, early removal, or incomplete follow-up are treated in an analysis. Those rules are not reported in the registry record.
What do the planning illustrations mean?
General sample-size calculations can illustrate how many participants per arm might be needed to detect an assumed effect under specified statistical assumptions. They are planning exercises, not observed results and not evidence that a study had a particular probability of detecting an effect. The registry record's stated illustration assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The assumed effect is described as a stated fraction of the observed effect.
Those assumptions do not change the actual design of this trial, which has a single group and no concurrent comparison. A two-arm planning illustration should not be read as a description of how participants were allocated in the trial, or as an observed power calculation. A sample-size illustration is especially dependent on the assumed effect: planning for a smaller fraction of an effect generally requires more information to distinguish it from no difference. That is a general statistical principle, not an additional result from this trial. The registry record does not report its own sample-size justification or statistical plan.
What can the safety counts establish?
Counts and percentages summarize recorded events in the study group. In general, a participant can experience more than one event, and a participant can be included under more than one event term. Therefore, event-term percentages should not be added to form a total, and event categories should not automatically be treated as mutually exclusive. These descriptive quantities also do not establish causation. A comparison group and a defined causal analysis would be needed to assess whether an event occurred more often because of the intervention.
The registry record gives group-level safety counts and selected serious-event terms, but it does not provide an analysis comparing risks, accounting for follow-up duration, or attributing events to the device or procedure. The counts should be read as reported observations in the FETO group. Their interpretation is constrained by the absence of a comparator and by the lack of further analysis information.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary endpoint and secondary outcomes for fetal lung growth and survival. It does not report a statistical analysis plan, a hierarchy for testing outcomes, or a method for controlling the chance of false-positive findings across multiple statistical tests. In general, testing several outcomes can increase the chance that at least one result appears statistically notable by chance. A prespecified hierarchy or multiplicity adjustment can address this concern, but no such approach is reported in the registry record.
The record lists no analyses and does not report inferential results for the primary or secondary outcomes. It is therefore not possible to assess whether outcomes were analyzed as prespecified, whether multiple testing was considered, or whether exploratory analyses were distinguished from confirmatory ones. The outcome names alone do not establish that a particular analysis was conducted.
Missing-data rules are also not reported in the registry record. The record does not describe how missing endpoint information, unsuccessful attempts, early removal, withdrawal, or incomplete follow-up would be handled. In general, missing observations can affect an estimate if the participants with available data differ from those without data. The direction and size of any such effect depend on why information is missing and on the analysis approach; neither is documented.
Analysis populations are not reported in the registry record. It is not stated whether the primary analysis would include all enrolled participants, only those who underwent attempted placement, or another defined group. The listed enrollment of 28 does not resolve which participants contributed to any outcome analysis. Without an analysis population and missing-data approach, the denominator and interpretation of a future endpoint estimate would need to be established from additional reporting.
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 |
|---|---|---|---|
| FETO in CDH | 28 | 28 | 100.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| FETO in CDH | 1 of 28 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| FETO in CDH | 13 of 28 |
Most frequent serious adverse event terms
| Event term | Organ system | FETO in CDH |
|---|---|---|
| Respiratory distress/failure (Neonatal) | Respiratory, thoracic and mediastinal disorders | 14 of 28 |
| Pulmonary hypertension (Neonatal) | Respiratory, thoracic and mediastinal disorders | 14 of 28 |
| Gastroesophageal reflux disease (Neonatal) | Gastrointestinal disorders | 14 of 28 |
| Feeding difficulties (Neonatal) | Gastrointestinal disorders | 14 of 28 |
| Tracheomegaly and/or tracheomalacia (Neonatal) | Respiratory, thoracic and mediastinal disorders | 13 of 28 |
| Preterm premature rupture of membranes | Pregnancy, puerperium and perinatal conditions | 11 of 28 |
| Preterm delivery ( < 37 weeks GA) | Pregnancy, puerperium and perinatal conditions | 11 of 28 |
| Preterm Labor | Pregnancy, puerperium and perinatal conditions | 10 of 28 |
| Premature birth with a weight of < 2500 gm (Neonatal) | Pregnancy, puerperium and perinatal conditions | 10 of 28 |
| Chorioamniotic membrane separation | Pregnancy, puerperium and perinatal conditions | 7 of 28 |
Most frequent non-serious adverse event terms
| Event term | Organ system | FETO in CDH |
|---|---|---|
| Reactive airway disease (Neonatal) | Respiratory, thoracic and mediastinal disorders | 6 of 28 |
| Grade 1 germinal matrix bleed (Neonatal) | Nervous system disorders | 4 of 28 |
| Prenatal abdominal pain (Maternal) | Pregnancy, puerperium and perinatal conditions | 2 of 28 |
| Vasovagal reaction to epidural placement (Maternal) | Vascular disorders | 1 of 28 |
| Ileus (Maternal) | Gastrointestinal disorders | 1 of 28 |
| Preeclampsia without severe features (Maternal) | Pregnancy, puerperium and perinatal conditions | 1 of 28 |
Serious events with the highest arm-level rate: respiratory distress/failure (neonatal) (50.0%), pulmonary hypertension (neonatal) (50.0%), gastroesophageal reflux disease (neonatal) (50.0%), feeding difficulties (neonatal) (50.0%), tracheomegaly and/or tracheomalacia (neonatal) (46.4%).
The registry record reports 28 participants at risk for serious adverse events and 28 affected. For other adverse events, it reports 28 at risk and 13 affected. It also reports 1 death. These are descriptive counts for the FETO group; they are not comparisons with an untreated group or another intervention. The registry record does not provide an analysis of whether the events were caused by the procedure or devices.
Selected serious adverse-event terms include neonatal respiratory distress or failure, pulmonary hypertension, gastroesophageal reflux disease, and feeding difficulties, each reported at 50.0%. Tracheomegaly and/or tracheomalacia is reported at 46.4%, and preterm premature rupture of membranes at 39.3%. These percentages describe the listed terms in the registry record. The record does not provide further details about timing, duration, severity grading, or relatedness for these events.
Event terms are not necessarily mutually exclusive: in general, one participant may experience more than one event. Percentages should not be added, and a higher listed percentage does not by itself indicate a causal relationship. The figures describe events recorded in a single-group trial and do not quantify excess risk relative to a comparator.
12. What the Result Does, and Does Not, Mean
The record describes a pilot study of FETO in severe left congenital diaphragmatic hernia and defines a primary procedural endpoint: successful balloon placement and removal. This makes the intended outcome clear, including the possibility of up to 3 insertion attempts and a maximum stated balloon duration of 7 weeks. The registry also lists fetal lung growth and survival as secondary outcomes and reports safety counts and selected serious-event terms.
However, the primary endpoint result is not reported in the registry record. No outcome analyses are listed. The registered enrollment of 28 does not reveal how many participants achieved the endpoint or how many had complete information. Without a reported estimate and uncertainty interval, the frequency and precision of procedural success cannot be assessed from this record.
The single-group design also limits what any treated-group outcome can establish. In general, an outcome observed after an intervention does not show what would have happened to comparable participants without it. There is no concurrent comparator in the registry record, so it does not support a randomized estimate of a difference between FETO and another approach. The recorded safety events likewise cannot be attributed to the intervention solely from their occurrence in the treated group.
The record therefore supports statements about the planned intervention, endpoint definition, trial design, status, and descriptive safety figures. It does not report a quantitative result for the primary endpoint, an analysis of fetal lung growth or survival, or a comparative estimate of benefits or harms. These limits are about the information documented in the registry record; they are not evidence that an outcome was favorable or unfavorable.
13. Why This Trial Matters Statistically
This trial illustrates why design and reporting details matter when reading clinical research. A procedural endpoint can answer a focused question about whether the intended intervention steps were completed. Here, success is defined through balloon placement and removal, while the procedure permits up to 3 insertion attempts and balloon duration can vary up to the stated maximum of 7 weeks. Those details help clarify what the endpoint means and what a future reported estimate would need to represent.
The single-group design is equally important. It can describe outcomes among participants who undergo FETO, but it cannot by itself show how those outcomes compare with what would occur under another care pathway. A reader should distinguish an observed outcome in the treated group from a treatment effect, which is a comparison between outcomes under different conditions.
The registry also makes visible the difference between defining an outcome and reporting its result. The primary endpoint is specified, but its result and analysis are not reported in the registry record. Without an estimate, its uncertainty, denominator, and handling of missing information cannot be evaluated. Safety counts can still be described, but they are not comparative and do not establish causation.
These distinctions are useful in biostatistics because they prevent design features, outcome definitions, and descriptive counts from being mistaken for evidence of comparative effectiveness. Clear interpretation depends not only on what was intended to be measured, but also on whether the outcome data, analysis methods, and relevant comparison are reported.
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 a primary endpoint result or analyses for the listed outcomes. Consequently, the intended procedural measure cannot be translated into an observed success estimate or a statement about its precision. The listed enrollment of 28 does not establish the endpoint denominator or the number with complete follow-up.
The single-group design has no concurrent control, so it cannot support a like-for-like estimate of how outcomes differ under FETO versus another approach. Masking is listed as none. The registry record does not describe further safeguards against measurement or assessment differences, and it does not report the statistical analysis plan.
The timing of balloon implantation can vary, although the registered maximum is 7 weeks. The record does not report individual exposure durations or how variation in timing is incorporated into outcome analysis. It also allows up to 3 insertion attempts but does not report how repeat or unsuccessful attempts are classified for analysis.
Missing-data handling, analysis populations, and multiplicity procedures are not reported in the registry record. The safety information is descriptive and lacks a comparative analysis or further details on event timing and relatedness. These specific gaps limit assessment of endpoint precision, robustness, and causal interpretation. They do not establish that the trial had no such procedures; they mean those procedures are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Fetoscopic Endoluminal Tracheal Occlusion in Severe Left Congenital Diaphragmatic Hernia — NCT02549820.
- Registry record last updated 2026-11-04; status last verified 2026-10.
- Results first posted 2026-11-04.
- 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
This registry record describes a pilot, single-group trial of fetoscopic endoluminal tracheal occlusion for severe left congenital diaphragmatic hernia. The intervention uses a detachable balloon in the fetal airway, with placement and removal forming the primary procedural endpoint. Insertion may be attempted up to 3 times, and the maximum stated implantation duration is 7 weeks.
The record lists an enrollment of 28, status as active, not recruiting, a start date of July 2015, and a primary completion date of May 1, 2025. It lists fetal lung growth and survival as secondary outcomes. The primary endpoint result and outcome analyses are not reported in the registry record. Safety counts and selected serious adverse-event percentages are reported for the single study group, without a concurrent comparator or a causal analysis.