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 Gastric Volumes by US in Term Parturients Undergoing CS With and Without Metoclopramide (NCT05033041), a randomized phase 4 study. The primary outcome is Change in Gastric Volume (mL).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05033041 |
| Phase | Phase 4 |
| Condition | Pregnancy, Cesarean Section, Aspiration |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 72 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Northwestern University |
| Results posted | Yes |
2. Clinical Question
Population
Term parturients who were appropriately fasted and scheduled for elective cesarean delivery. The registry record notes that one participant in the placebo group did not have a paired ultrasound because the pretreatment measurement was missing.
Intervention
Intravenous administration of 10 mg metoclopramide before the scheduled cesarean delivery.
Comparator
Intravenous administration of sterile normal saline as placebo.
Primary question
How did gastric volume change between the ultrasound measurement before study drug and the measurement 30 minutes after administration, and did the change differ between the metoclopramide and placebo groups?
The trial's stated objective was to compare gastric volumes in appropriately fasted patients receiving metoclopramide or placebo before scheduled cesarean delivery. Its hypothesis was that metoclopramide would not produce a clinically significant reduction in gastric volume in this setting. That statement describes the investigators' hypothesis; it is not a result.
A secondary objective was to evaluate whether gastric volume predicted intraoperative nausea and vomiting. Other registered secondary outcomes include subject-reported nausea, adverse events, nausea and vomiting occurrences and their timing, and antiemetic prophylaxis. The registry record does not report results for these questions. It also does not report a primary comparison estimate or its confidence interval, so the direction and precision of any between-group difference cannot be assessed from the record.
3. Trial Design
This was a phase 4, randomized, parallel-group trial with quadruple masking. The registry lists an enrollment of 72 and a completed status. The study began on 2021-10-20, and the primary completion date was 2024-01-30. The trial was sponsored by Northwestern University.
Participants were assigned to one of two study-drug groups: intravenous 10 mg metoclopramide or intravenous sterile normal saline placebo. The study concerned term parturients undergoing scheduled elective cesarean delivery who were appropriately fasted. The registry record does not specify the allocation ratio, the randomization procedure, or which groups of people were included in quadruple masking. Those details should not be inferred from the design labels.
The primary outcome was change in gastric volume, measured by gastric ultrasound before study drug and 30 minutes after its administration. The primary outcome is described using a median and a 95% confidence interval. The record notes one participant in the placebo group without a paired ultrasound measurement because the pretreatment ultrasound was missing.
The registered secondary outcomes cover nausea, vomiting, adverse events, timing of intraoperative episodes, and antiemetic prophylaxis. The registry lists 24 outcome measures and one analysis, but does not report the statistical analysis plan or outcome results. In particular, it does not report how the primary comparison was estimated, how missing measurements were handled, or which analysis population was used. Completion status indicates the trial is recorded as completed; it does not establish that all registered results are posted.
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 | Group 1 Study Drug Metoclopramide | Group 2 Study Drug Placebo |
|---|---|---|
| STARTED | 38 | 34 |
| COMPLETED | 38 | 34 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: One subject in the placebo group did not have a paired ultrasound (missing pre-treatment).
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 | Group 1 Study Drug Metoclopramide | Group 2 Study Drug Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 38 | 34 | 72 | |
| Age, Continuous | Years | 35 (33 to 38) | 35 (32 to 39) | 35 (32 to 39) |
| Sex: Female, Male: Female | Participants | 38 | 34 | 72 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 7 | 3 | 10 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 31 | 31 | 62 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 2 | 0 | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 2 | 2 |
| Race (NIH/OMB): White | Participants | 36 | 32 | 68 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 38 | 34 | 72 |
| Weight (kg) | Kilograms | 80.5 (73.3 to 86) | 79.5 (73.3 to 86) | 80 (73.3 to 86) |
| Body Mass In kg/m^2 | kg/m^2 | 29.8 (27.4 to 31.8) | 29.6 (26.2 to 33.1) | 29.7 (26.2 to 33.1) |
| Gestational age (weeks) | Weeks | 39.1 (39 to 39.2) | 39.1 (39 to 39.3) | 39.1 (39 to 39.3) |
| Gravid (number of pregnancies): Gravid 1 | Participants | 9 | 3 | 12 |
| Gravid (number of pregnancies): Gravid 2 | Participants | 12 | 16 | 28 |
| Gravid (number of pregnancies): Gravid 3 | Participants | 6 | 8 | 14 |
| Gravid (number of pregnancies): Greater or equal to gravid 4 | Participants | 11 | 7 | 18 |
| Parity: 0 | Participants | 12 | 4 | 16 |
| Parity: 1 | Participants | 21 | 22 | 43 |
| Parity: 2 | Participants | 5 | 5 | 10 |
| Parity: Greater or equal to 3 | Participants | 0 | 3 | 3 |
| Prior cesarean deliveries | Participants | 25 | 29 | 54 |
| Gastroesophageal reflux disease (GERD): With pregnancy | Participants | 31 | 24 | 55 |
| Gastroesophageal reflux disease (GERD): Currently | Participants | 4 | 7 | 11 |
| Hours since last solid ingestion (NPO) | Hours | 12.5 (7.5 to 13.7) | 12.9 (8.3 to 14.6) | 12.7 (7.5 to 14.6) |
| Time from last liquid ingestion (hours) | Hours | 3.3 (3 to 3.7) | 3.4 (3 to 4.4) | 3.3 (3 to 4.4) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Gastric Volume (mL), measured over 30 minutes after administration of study drug.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | Milliliters |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is change in gastric volume, in milliliters, determined from gastric ultrasound before and 30 minutes after study-drug administration. This paired measurement aims to capture how gastric volume changed over the interval after metoclopramide or placebo, rather than relying only on a single measurement at one time. The comparison of interest is the difference in change between the randomized groups.
The registry describes gastric volume calculation using two approaches. The Perlas method uses the right lateral decubitus (RLD) cross-sectional area and age. The Roukhomovsky method uses RLD and supine (SUP) cross-sectional areas. These are ultrasound-based estimates derived from measured cross-sectional areas; they are not direct measurements of aspirated stomach contents. The registry record does not report which method underlies any posted numerical result or how the two calculations relate to the primary comparison.
Gastric volume is used as a measured physiological outcome relevant to the trial's stated aspiration-prophylaxis question. It is not itself an aspiration event. The endpoint therefore addresses a surrogate measurement, while the registered secondary outcomes include nausea and vomiting during cesarean section. The registry record does not report primary endpoint values, a between-group estimate, or its 95% confidence interval. The magnitude and precision of the observed change cannot be described from the record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes the trial question and design, but it does not report the primary outcome results. It identifies change in gastric volume as the primary outcome and specifies a median with a 95% confidence interval, measured 30 minutes after study-drug administration. It does not give the median change for either group, a comparison between groups, or the confidence interval for such a comparison. Consequently, the direction, size, and precision of the primary finding are not reported in the registry record.
The investigators' stated hypothesis was that metoclopramide would not yield a clinically significant reduction in gastric volume among appropriately fasted patients. A hypothesis is not evidence that the anticipated result occurred. Without outcome values, the posted record cannot establish whether the observed data were consistent with that hypothesis, differed from it, or were too imprecise to distinguish among plausible effects. No claim about benefit or lack of benefit follows from the absence of results in this registry entry.
The primary endpoint is based on ultrasound measurements before and after administration. The registry says one placebo participant lacked a paired measurement because the pretreatment ultrasound was missing. It does not explain whether that participant was excluded from the primary analysis, whether another method was used to address the missing measurement, or how many participants contributed to the reported endpoint. No completed analysis population is described.
The registry lists secondary outcomes involving nausea, vomiting, adverse events, and antiemetic prophylaxis, but does not report their results. It therefore does not support conclusions about the frequency or timing of nausea or vomiting, the association between gastric volume and those events, or differences in adverse events between groups. The serious adverse event counts are reported separately and are described under safety reading; they do not substitute for the missing primary endpoint findings.
General statistical context: an estimate describes the observed difference, while a confidence interval conveys uncertainty around that estimate under the analysis used. Neither can be interpreted without the actual estimate and interval. The trial's enrollment and design information alone do not reveal how precisely the gastric-volume comparison was estimated. A completed status likewise does not fill in the absent results.
9. Statistical Methods Explained
What does the primary measurement represent?
The endpoint is a change score: gastric volume is measured before study drug and again 30 minutes after administration, and the change between those measurements is the outcome of interest. In general, paired measurements can account for each participant's starting measurement when describing change over time. The comparison between randomized groups then asks whether the changes differed between the treatment assignments. The registry record does not report the calculation used to produce a group comparison or whether the analysis used individual change scores or another approach.
The outcome is described with a median and a 95% confidence interval. In general, a median is the middle of an ordered set of observations and can describe a typical value without requiring a symmetric distribution. A confidence interval expresses uncertainty about an estimated quantity under the assumptions of the statistical method. It is not a range containing a specified proportion of individual participants' measurements. The registry does not provide the values needed to interpret the endpoint's median or interval.
How does the ultrasound calculation work?
The registry describes two calculation methods based on ultrasound cross-sectional area. The Perlas method uses the RLD cross-sectional area and age; the registry gives its formula as Volume=27.0+14.6*(RLD CSA (cm2)-1.28 * age). The Roukhomovsky method uses both RLD and SUP cross-sectional areas; its stated formula is volume=(0.18*RLD CSA (mm2))+(0.11*SUP CSA (mm2)-62.4). These equations transform ultrasound measurements into estimated gastric volumes. The record does not say which method posted the primary outcome results or report results separately by method.
General measurement context: an estimate derived from an imaging measurement may reflect both the underlying biological quantity and uncertainty in measurement and calculation. Using a specified method helps define what the endpoint represents, but does not by itself establish the accuracy of a particular measurement. The registry does not report measurement reliability, assessor procedures, or details of how discrepancies between methods were handled.
What does randomization contribute?
General statistical context: random assignment is intended to make treatment groups comparable on average with respect to measured and unmeasured characteristics, subject to chance variation. It supports interpreting a between-group comparison as an effect of assignment when the design and analysis are appropriately implemented. The registry labels the trial randomized, but the randomization sequence, allocation concealment, and implementation details are not reported. The parallel-group model indicates that participants were assigned to one of the study-drug groups rather than both in a crossover sequence.
Quadruple masking is the registry's masking designation. General context: masking can reduce the influence of expectations on participant reports, clinical care, outcome assessment, or analysis, depending on who is masked. The record does not identify which four roles were masked or describe how masking was maintained. The masking label should not be taken as evidence about specific procedures beyond what the registry states.
How should uncertainty and significance be read?
In general, a confidence interval communicates both the estimated effect and its statistical uncertainty. A narrow interval indicates greater precision than a wide interval for the same estimand and analysis, while an interval that includes values on both sides of a null difference may leave the direction uncertain. Such interpretation depends on the comparison and interval actually reported. No primary estimate or confidence interval is reported in the registry record, so these concepts cannot be applied to a numerical trial result.
The registry describes the endpoint with a 95% confidence interval, but does not report a p-value, a significance threshold, or the statistical test used for the primary comparison. Those features of the analysis plan are not reported in the registry record. A non-significant result, if one existed, would not alone demonstrate equivalence or absence of a clinically important difference; equivalence requires a defined margin and an analysis designed to assess it. The record does not report such a margin or an equivalence analysis.
What do planning calculations mean?
General context: sample-size planning illustrations estimate how many participants might be needed under stated assumptions. They are not observed trial outcomes and should not be described as observed power. The registry's planning description says the illustrations use the observed effect, a two-sided significance level of 0.05, equal allocation, a normal approximation, and a stated fraction of the observed effect. It specifies that non-time-to-event calculations are expressed as participants per arm for 80% power or other stated planning levels, while time-to-event calculations use a total event count.
These assumptions describe planning illustrations, not necessarily the trial's original design. The registry does not report the trial's own sample-size justification or show numeric planning estimates in the record. In general, calculations based on an observed effect can be unstable because an effect estimated in a trial is uncertain. They should not be read as evidence that the trial had a particular probability of detecting an effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 24 outcome measures, including the primary gastric-volume outcome and secondary measures concerning nausea, vomiting, adverse events, timing, and antiemetic prophylaxis. When a study evaluates multiple outcomes or multiple categories and time points, general statistical reasoning recognizes a multiplicity issue: the chance of at least one apparently notable result can rise when many comparisons are examined. The registry record does not report whether any adjustment for multiple comparisons was planned or used, nor does it describe a hierarchy among secondary outcomes.
The record lists one analysis, but it does not provide the statistical analysis plan or enough detail to establish which outcomes, contrasts, or time points that analysis covered. The primary outcome is identified as having several categories or time points and is not reduced to one comparison in the registered summary. No single primary comparison result is reported. Thus, it is not possible to determine from this record how the outcome structure was handled analytically.
Missing data are noted for one participant in the placebo group, who did not have a paired ultrasound because the pretreatment measurement was missing. The registry does not report the total analyzed population, how that observation was treated, whether any imputation was used, or whether sensitivity analyses assessed the effect of missing data. The analysis population—such as all randomized participants or those with complete paired measurements—is not reported in the registry record.
General context: missing outcome measurements can affect precision and, depending on why they are missing and how they are handled, can also affect the estimated comparison. A missing-data method cannot be inferred from a participant count or from the randomized design. No assumptions about the missing ultrasound or analysis population should be made beyond the registry's statement that one paired measurement was unavailable.
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 |
|---|---|---|---|
| Group 1 Study Drug Metoclopramide | 0 | 38 | 0.0% |
| Group 2 Study Drug Placebo | 0 | 34 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Group 1 Study Drug Metoclopramide | 0 of 38 |
| Group 2 Study Drug Placebo | 0 of 34 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Group 1 Study Drug Metoclopramide | 3 of 38 |
| Group 2 Study Drug Placebo | 6 of 34 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Group 1 Study Drug Metoclopramide | Group 2 Study Drug Placebo |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 3 of 38 | 6 of 34 |
| Hypertension | Blood and lymphatic system disorders | 3 of 38 | 6 of 34 |
The registry's serious adverse event figures list zero affected participants in the metoclopramide group and zero in the placebo group. The number at risk is listed as 38 for metoclopramide and 34 for placebo. The record also lists zero deaths in each group. These are the posted serious-event counts; they should not be treated as evidence that no events of any kind occurred.
For other adverse events, the registry lists three affected participants in the metoclopramide group and six in the placebo group, with 38 and 34 participants at risk, respectively. The record does not provide event terms in the serious-event category, and it does not specify in this summary whether the other-event counts represent unique people with at least one event or event occurrences. The serious-event and other-event categories should therefore be kept distinct rather than combined.
General statistical context: counts from a trial of this size describe what was recorded in the study, but do not by themselves establish comparative safety or rule out uncommon harms. The registry does not report a statistical comparison for adverse events, event-level details, or follow-up duration for safety outcomes. These figures are descriptive registry results, not a basis for individual medical decisions.
12. What the Result Does, and Does Not, Mean
The registry record identifies a randomized comparison of metoclopramide and placebo in appropriately fasted term parturients undergoing scheduled elective cesarean delivery. Its main scientific question concerns gastric-volume change measured by ultrasound before and 30 minutes after study-drug administration. The study also registered outcomes related to intraoperative nausea and vomiting and adverse events.
What the record does not provide is the primary outcome result. There is no group-specific median change, between-group estimate, or 95% confidence interval in the registry entries available for this analysis. Without those values, it is not possible to describe whether gastric volume increased or decreased in either group, whether the groups differed, or how precisely any difference was estimated. The investigators' stated hypothesis is not a substitute for observed data.
Even if a gastric-volume comparison were reported, it would address a measured ultrasound-based endpoint, not directly establish an effect on aspiration. The registry's secondary outcomes include nausea and vomiting, but their results are also not reported. Therefore the record does not establish whether gastric volume predicted those events or whether their frequency differed by assigned group.
General statistical context: absence of a reported estimate is different from evidence of no effect. A study's completion status and enrollment do not reveal the size or precision of its observed effect. Likewise, a planning illustration based on an observed effect is not a trial result and is not observed power. The registry entry permits description of the research question, design, and posted safety counts, but leaves the central comparative efficacy finding unresolved.
13. Why This Trial Matters Statistically
This trial illustrates why the endpoint definition and the reported analysis both matter. A before-and-after ultrasound measure, summarized as a median with a 95% confidence interval, specifies a physiological outcome and its timing. To interpret the randomized comparison, readers also need the actual group estimates, a between-group contrast, and uncertainty around that contrast. The registry record describes the measurement but does not report those results.
The design also places measurement choices in focus. Gastric volume is calculated from ultrasound cross-sectional areas using named methods, and the record describes formulas using different positions and measurements. Knowing which calculation was used in the primary analysis would help clarify the estimand and interpretation. That information is not reported alongside a primary outcome result in the registry record.
Multiplicity and missingness are relevant because multiple outcome measures are registered, the primary outcome includes several categories or time points, and one placebo participant lacks a paired ultrasound. These features do not invalidate a study, but they make a transparent analysis plan and clear reporting important. The registry record does not describe multiplicity handling, the missing-data approach, or the analysis population.
The trial is therefore statistically informative as a case in distinguishing a stated hypothesis and trial design from an observed finding. Enrollment, masking, and completion status do not reveal the effect estimate. Clear outcome reporting is necessary before readers can assess direction, magnitude, precision, or the relationship between the physiological endpoint and the secondary clinical observations.
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 principal limitation for interpreting this registry entry is that it does not report the primary gastric-volume result. No group-specific median changes, comparative estimate, or confidence interval are available in the record. This prevents assessment of the direction, magnitude, and precision of the primary comparison.
The registry also does not report how the primary endpoint was analyzed, which ultrasound calculation method posted the primary analysis, or how the multiple outcome categories and time points were handled. It identifies 24 outcome measures and one analysis, but does not provide a statistical analysis plan, adjustment approach for multiplicity, or analysis population. The numerical outcome results for the registered secondary measures are not reported either.
One placebo participant lacked a paired ultrasound because the pretreatment measurement was missing. The record does not state how that missing measurement was handled or whether sensitivity analyses were performed. It also does not report measurement reliability or details of who performed or assessed the ultrasound measurements.
The design labels do not resolve all implementation questions: the allocation ratio, randomization procedure, and the roles included in quadruple masking are not reported. The record's stated endpoint is an ultrasound-derived gastric-volume change, which is distinct from aspiration itself. Finally, the registry's safety summary gives counts but does not report event-level descriptions or a statistical comparison. These reporting gaps limit interpretation of efficacy, measurement, and safety findings from this record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Gastric Volumes by US in Term Parturients Undergoing CS With and Without Metoclopramide — NCT05033041.
- Registry record last updated 2025-09-11; status last verified 2025-08.
- Results first posted 2025-05-08.
- 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
NCT05033041 is a completed phase 4 randomized, quadruple-masked, parallel-group trial sponsored by Northwestern University. It lists enrollment of 72. The study began on 2021-10-20, with primary completion on 2024-01-30.
The trial compared intravenous 10 mg metoclopramide with intravenous sterile normal saline placebo in appropriately fasted term parturients scheduled for elective cesarean delivery. The primary outcome was change in ultrasound-derived gastric volume before and 30 minutes after study-drug administration, described using a median and 95% confidence interval. One placebo participant did not have a paired ultrasound because the pretreatment measurement was missing.
The registry lists 24 outcome measures, including nausea, vomiting, adverse events, and antiemetic prophylaxis. It reports zero serious adverse events and zero deaths in each group, with other adverse events affecting three participants in the metoclopramide group and six in the placebo group. The primary outcome estimate, secondary outcome results, analysis population, and methods for missing data and multiplicity are not reported in the registry record.