Spinal Anesthesia Induced Hypotension During Cesarean Section: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Spinal Anesthesia Induced Hypotension During Cesarean Section (NCT00846651), a randomized phase 4 study. The primary outcome is Incidence of Maternal Hypotension.

2. Clinical Question

The comparison concerns the two treatment strategies as recorded, not colloid or crystalloid in isolation: phenylephrine was part of both arm descriptions. The registry record does not report a definition or threshold for maternal hypotension, so the exact event criteria cannot be assessed from the record. It also does not describe whether other aspects of care were standardized. The results therefore address the posted comparison and its measured endpoint, while leaving some details needed to interpret how hypotension was identified unavailable.

3. Trial Design

The record describes a phase 4, randomized, parallel-group trial with no masking. Its status is completed. The listed start date is 2009-02, and the primary completion date is 2009-12. Milton S. Hershey Medical Center is identified as the sponsor. Enrollment is reported as 82.

The two arms differed in the fluid administered before or around spinal anesthesia. The colloid arm used hydroxyethylstarch, while the crystalloid arm used Ringer’s lactate. Both arm descriptions include phenylephrine infusion initiated immediately after performing the spinal anesthetic. The colloid description says the infusion continued until uterine incision. The crystalloid description is incomplete at its final phrase, so its specified stopping point is not reported in the registry record.

Random assignment is relevant because it is intended to balance other characteristics between groups on average, but the record does not report the sequence-generation method, allocation concealment, or whether randomization was stratified. With no masking, treatment assignment was not masked according to the registry entry. The record does not report whether outcome assessors were masked separately.

The primary outcome results list 37.0 participants per arm. The adverse-event reporting uses 41 participants at risk per arm; the registry record does not explain the difference between these reported denominators. It also does not report participant flow, withdrawals, exclusions, or the analysis population used for each outcome. The trial design can therefore be described from its randomized parallel structure and assigned interventions, but some implementation and analysis details remain unavailable.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Incidence of Maternal Hypotension, measured over participants were assessed for an average of 20 min, after performing the spinal anesthetic till the delivery of the baby.

The primary endpoint is the incidence of maternal hypotension, expressed as the percentage of participants with the event. The registry record says participants were assessed for an average of 20 min, after spinal anesthetic administration until delivery of the baby. It does not report the threshold, measurement rule, or clinical criteria used to classify hypotension. The precise event definition is therefore not reported in the registry record.

An incidence endpoint describes how often an event occurred in each arm during the stated assessment period. Comparing these proportions gives a direct account of the outcome recorded under the two treatment strategies. The endpoint is relevant to the trial’s stated purpose of comparing approaches intended to prevent low blood pressure associated with spinal anesthesia during cesarean section. It is not, by itself, a complete assessment of all maternal or fetal outcomes.

In the posted results, the reported incidence was 10.8% for colloid followed by phenylephrine infusion and 27.0% for crystalloid followed by phenylephrine infusion. These are group-level estimates, and their interpretation should consider the uncertainty in the between-arm comparison as well as the missing details about event definition and analysis. The endpoint does not establish how long hypotension lasted or its severity, because those measures are not reported in the registry record.

7. Results Posted in the Registry

• Crystalloid, Then Phenylephrine Infusion: 27.0% (10/37) versus 10.8% (4/37) on control; risk difference 16.2 percentage points (95% CI -1.2 to 33.7), risk ratio 2.50 (0.86–7.26); unadjusted two-proportion z-test p = 0.075.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Dosage of Phenylephrine Used

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Crystalloid, Then Phenylephrine Infusion: mean 1,477 versus 1,077 on control; difference 400.00 (95% CI 141.83 to 658.17), standardized effect d = 0.71; z-test p = 0.002.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Crystalloid, Then Phenylephrine Infusion than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Incidence of Maternal Bradycardia

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Crystalloid, Then Phenylephrine Infusion: 45.9% (17/37) versus 35.1% (13/37) on control; risk difference 10.8 percentage points (95% CI -11.4 to 33.0), risk ratio 1.31 (0.75–2.29); unadjusted two-proportion z-test p = 0.344.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Crystalloid, Then Phenylephrine Infusion and the control. The interval gives the range of effects that remain compatible with the data.

Incidence of Maternal Nausea and Vomiting

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Crystalloid, Then Phenylephrine Infusion: 18.9% (7/37) versus 16.2% (6/37) on control; risk difference 2.7 percentage points (95% CI -14.6 to 20.0), risk ratio 1.17 (0.43–3.14); unadjusted two-proportion z-test p = 0.760.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Crystalloid, Then Phenylephrine Infusion and the control. The interval gives the range of effects that remain compatible with the data.

The registry record lists five secondary outcomes. Numerical results are posted for phenylephrine dosage, maternal bradycardia, and maternal nausea and vomiting. Results for fetal cord blood pH and APGAR scores are not reported in the registry record. This leaves the secondary-outcome picture incomplete and limits any assessment spanning maternal and fetal measures.

Across the outcomes with results, the observed group patterns are not uniform in their apparent size or statistical precision. The dosage comparison has a narrower-looking evidential signal than the binary secondary comparisons, while the latter have confidence intervals that include no difference and unadjusted p-values that do not indicate a clear separation. This broad pattern does not resolve the primary question: secondary outcomes measure different events or quantities and cannot substitute for the primary hypotension endpoint.

General statistical explanation: examining multiple outcomes increases the chance that some may appear noteworthy by chance, particularly when each is assessed separately. An unadjusted p-value does not account for the number of outcomes considered. The registry record does not report a multiplicity correction, an outcome hierarchy, or a strategy for treating secondary endpoints as confirmatory versus exploratory. Thus, the secondary results should carry less inferential weight than a prespecified primary result and should be interpreted as supportive or exploratory evidence rather than as independent confirmation.

The missing results are also important. Without posted fetal cord blood pH and APGAR results, a reader cannot determine the full pattern of recorded secondary outcomes. The registry record does not explain why those results are absent. It would be inappropriate to infer either favorable or unfavorable findings from the lack of results. Taken together, the available secondary outcomes offer context about the trial’s measured outcomes, but they do not establish a broad effect across maternal and fetal endpoints.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Dosage of Phenylephrine Used
• Incidence of Maternal Bradycardia
• Fetal Cord Blood pH
• APGAR Scores
• Incidence of Maternal Nausea and Vomiting

9. Statistical Interpretation

10. Statistical Methods Explained

What does the risk difference express?

A risk difference subtracts one group’s event proportion from the other’s. In this comparison, the direction is crystalloid followed by phenylephrine infusion relative to colloid followed by phenylephrine infusion. The estimate is 0.162. A positive value means the observed event proportion was higher in the crystalloid arm; it does not by itself establish that the underlying treatment effects differ. The confidence interval from -0.012 to 0.337 describes the uncertainty around this unadjusted estimate.

General statistical explanation: a confidence interval is a range of values compatible with the data under the method used to calculate it. An interval that includes zero for a difference means the data do not clearly rule out no difference. It can also include values representing a difference in either direction. The interval’s width is important: a wide interval leaves considerable uncertainty about the size and direction of the underlying difference. The confidence level and exact interval method are not reported in the registry record.

How should the p-value be read?

The unadjusted p-value for the primary comparison is 0.075. A p-value describes how unusual data at least as discrepant as those observed would be under a specified null model. It is not the probability that the null hypothesis is true, and it is not a measure of the chance that the finding is due to chance. The record does not report the sponsor’s full statistical analysis plan or a prespecified hypothesis-testing procedure. The stated planning assumptions use a two-sided significance level of 0.05, but that planning detail should not be mistaken for a complete account of the original analysis plan.

General statistical explanation: a p-value below a chosen threshold does not measure clinical importance, and one above that threshold does not prove there is no effect. Estimates and confidence intervals help show the range of effects compatible with the data, while design and measurement details affect how much confidence to place in the comparison.

What do relative measures add?

The posted comparison also gives a risk ratio of 2.5, with a confidence interval from 0.861 to 7.261, and an odds ratio of 3.056, with a confidence interval from 0.861 to 10.84. These measures compare groups on relative rather than absolute scales. Their intervals include the null value of one, consistent with the uncertainty indicated by the risk-difference interval. Relative measures can sound large even when event counts are limited, so they should be interpreted together with the absolute group percentages and the risk difference. The intervals are broad and do not identify a precise relative effect.

Why can small event counts matter?

The primary outcome counts were 4 in the colloid arm and 10 in the crystalloid arm, with 37.0 reported for each group. When event counts are limited, estimates of event proportions and between-group differences can be sensitive to a small change in the number of observed events. General statistical explanation: the sampling variability of a binary outcome depends partly on the event frequency and group size. This contributes to uncertainty in the comparison and is one reason not to interpret a point estimate without its interval.

General statistical explanation: over-dispersion is relevant when variability in observed outcomes is greater than a model assumes. In that circumstance, a model that does not account for the extra variability can understate uncertainty. The primary result is presented as an unadjusted binary comparison, and the registry record does not report use of an over-dispersion model or any adjusted model. No claim about over-dispersion in this trial can be made from the posted information.

What can the recalculated summaries establish?

The posted simple unadjusted comparisons quantify differences in the reported group summaries. They do not adjust for covariates, account for unreported participant-level information, or resolve missing data. The record flags no discrepancy between the posted summaries and the simple recalculations. No adjusted analysis is reported. The calculated comparisons therefore should not be described as the trial’s full analysis plan or as evidence that adjustment was unnecessary.

For the continuous secondary outcome of phenylephrine dosage, the reported mean was 1077.0 mcg in the colloid arm and 1477.0 mcg in the crystalloid arm. The unadjusted mean difference was 400.0 mcg, with a confidence interval from 141.8 to 658.2 and an unadjusted p-value of 0.002. The reported standard deviations were 541.0 and 591.0. General statistical explanation: a mean difference describes the difference in group averages, while the standard deviations describe spread among observations within each group. These statistics do not reveal the shape of the individual-level distributions.

For binary secondary outcomes with posted results, risk differences and unadjusted p-values are also reported. These are simple comparisons of the observed group results, not adjusted causal estimates. Across outcomes, the statistical summaries should be read as estimates with uncertainty, not as a substitute for knowing the endpoint definitions, data completeness, and analysis procedures. Those details are not reported in the registry record.

11. Confidence Intervals and Precision

The primary risk-difference estimate is 0.162, and its confidence interval extends from -0.012 to 0.337. The interval includes zero and spans values corresponding to a difference in either direction. This means the data leave uncertainty about whether the underlying event proportions differ and about the size of any difference. The point estimate alone would conceal that uncertainty.

The relative measures convey a similar caution. The risk ratio is 2.5, with a confidence interval from 0.861 to 7.261; the odds ratio is 3.056, with a confidence interval from 0.861 to 10.84. Both intervals include one, the value corresponding to no relative difference. Their breadth indicates that the estimate of the relative comparison is not precise. The registry record does not report the confidence-interval level or calculation method.

For context, the primary outcome was recorded for 37.0 participants per arm, with 4 and 10 events, respectively. General statistical explanation: estimates based on limited numbers of events commonly have appreciable sampling uncertainty. The group percentages—10.8% and 27.0%—are observed proportions, not exact values for the underlying populations. A confidence interval is intended to communicate that distinction.

The interval should not be treated as a probability statement about the true effect, and it does not rule out every potentially meaningful difference. The record does not report what size of difference would be considered clinically important. Precision is therefore best described in statistical terms: the primary comparison is uncertain, with an interval that includes no difference and extends across a range of possible effects.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total participants. The listed calculation uses equal allocation between two arms, a two-sided significance level of 0.05, and a normal approximation. It considers detecting a stated fraction of the observed effect. These assumptions describe a planning illustration; the trial’s original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the number of participants per arm estimated to provide an 80% chance of detecting the chosen effect under the stated assumptions, if that effect is real and the assumptions hold. The 90% power column gives the corresponding planning target for a 90% chance. These percentages describe long-run operating characteristics of a design, not the probability that the trial’s conclusion is correct.

For the primary outcome, planning for 100% of the observed effect gives 91 participants per arm for 80% power and 121 participants per arm for 90% power. Planning for 75% of the observed effect gives 148 participants per arm for 80% power and 198 participants per arm for 90% power. Planning for 50% of the observed effect gives 302 participants per arm for 80% power and 403 participants per arm for 90% power. Smaller target effects require more participants because they are harder to distinguish from random variation.

These figures are not observed power. They are hypothetical planning illustrations derived from the observed effect, not evidence about the trial’s original design or a retrospective measure of whether its result was reliable. The sample-size curve should be interpreted in the same way: it reflects how a planning target changes with the effect assumed for a future design, under the stated assumptions.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.108; treatment proportion p₁ = 0.270; average p̄ = 0.189.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5539 = 1.0856.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5419 = 0.4561.
4. n = (1.0856 + 0.4561)² / (0.1622)² = 90.4, rounded up to 91 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.108108108108108                          # control proportion
p1 <- 0.27027027027027                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(846651)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 91 (80% power), 121 (90% power)
 75% of observed effect: n per arm = 148 (80% power), 198 (90% power)
 50% of observed effect: n per arm = 302 (80% power), 403 (90% power)
power.prop.test: 90.4 
Simulated power at n = 91 per arm: 0.809 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record identifies a primary endpoint and several secondary outcomes, but it does not report how the investigators planned to control the risk of false-positive findings across multiple comparisons. No multiplicity adjustment, testing hierarchy, or distinction between confirmatory and exploratory secondary analyses is reported in the registry record. The posted secondary p-values are unadjusted. When multiple outcomes are examined, isolated findings can occur by chance more often than when one comparison is considered alone; this makes unadjusted secondary results less definitive.

The registry record does not report the statistical analysis plan, analysis populations, or whether the primary analysis followed intention-to-treat principles. It does not describe exclusions, withdrawals, protocol deviations, or how participants with unavailable outcome measurements were handled. Missing-data methods and sensitivity analyses are not reported in the registry record. As a result, the effect of missing or excluded observations on the posted comparisons cannot be assessed.

Reported denominators are not identical across outcome reporting: primary outcome results list 37.0 participants per arm, whereas adverse-event reporting lists 41 participants at risk per arm. The record does not reconcile these figures or explain whether they reflect different analysis populations, reporting conventions, or outcome availability. No explanation should be inferred from the difference alone.

Fetal cord blood pH and APGAR scores are listed as secondary outcomes, but their results are not reported in the registry record. The absence of posted values does not indicate what those results were. The record also does not report a protocol-defined approach to interim analyses, stopping rules, or adjustment for repeated testing over time. These omissions limit evaluation of selective reporting and the full evidential context, without establishing that any particular problem occurred.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

For each arm, the adverse-event record lists 41 participants at risk for serious adverse events and 0 affected. It also lists 41 participants at risk for other adverse events and 0 affected. No serious-event terms are listed. Deaths are not reported in the registry record.

These entries describe what was recorded in the adverse-event fields; they should not be interpreted as proving that no adverse events occurred in any broader sense. The record does not provide event definitions, surveillance procedures, reporting windows, or an explanation of how these safety denominators relate to the primary outcome denominators. Zero affected in the posted fields is therefore a limited safety summary, not a comprehensive estimate of risk. The registry record also does not provide enough information to compare safety precisely between the strategies.

16. What the Result Does, and Does Not, Mean

The posted primary result is a comparison of maternal hypotension incidence between two randomized arms that both included phenylephrine infusion and differed in the reported fluid regimen. The observed incidence was 10.8% with colloid followed by phenylephrine infusion and 27.0% with crystalloid followed by phenylephrine infusion. The unadjusted risk difference was 0.162, with a confidence interval from -0.012 to 0.337 and an unadjusted p-value of 0.075.

This result does not establish that the strategies are equivalent. The confidence interval includes no difference, but also spans differences in either direction. Nor does the result establish a definite difference: the estimate remains uncertain, and the p-value does not cross the 0.05 benchmark used in the stated planning assumptions. Statistical uncertainty and clinical importance are separate questions; the registry record does not report a threshold for a clinically important difference.

The comparison should not be interpreted as an isolated test of colloid versus crystalloid under otherwise identical conditions unless that is supported by the trial’s full protocol, which is not reported in the registry record. The arms involved specific fluid amounts, rates, timing, and phenylephrine infusion. The result concerns those recorded strategies, not every possible fluid choice or phenylephrine regimen.

The record also leaves important interpretive details unavailable: the definition of hypotension, the analysis population, missing-data handling, and the reason for differing denominators across primary and adverse-event reporting. These limitations do not invalidate the posted numbers, but they constrain what can be concluded about measurement, completeness, and generalizability. The numerical direction of the observed difference is clear in the reported percentages; its magnitude and implications remain uncertain.

17. Why This Trial Matters Statistically

This trial illustrates why an observed difference and a statistically precise conclusion are not the same thing. The group percentages point in one direction, but the confidence interval for the risk difference includes zero and extends across a range of possible effects. Reporting the estimate alongside its interval makes uncertainty visible rather than treating a single number as conclusive.

It also shows why the definition of an endpoint matters. “Maternal hypotension” is the primary outcome, but the registry record does not report the threshold or measurement rule. Without that information, readers cannot fully evaluate whether the outcome was consistently classified or compare it directly with studies using other definitions. Endpoint timing is reported as an average of 20 min, from spinal anesthetic administration until delivery, but duration and severity are not separately described.

The trial’s results also illustrate the distinction between a primary comparison and a set of secondary outcomes. Several secondary outcomes are listed, but results are absent for two and no multiplicity approach is reported. Treating every unadjusted result as equally confirmatory would overstate what the record supports.

Finally, the difference between the primary outcome denominators and adverse-event risk denominators is a reminder that clear reporting of populations and outcome availability is essential. The record does not explain that difference. These statistical features are relevant beyond this trial: estimates, uncertainty, endpoint definitions, and transparent analysis populations all shape how clinical evidence can be interpreted.

18. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

Several trial-specific details needed to assess the result are not reported in the registry record. The definition and threshold for maternal hypotension are absent, as are details of measurement frequency and severity. Although the assessment period is described as an average of 20 min, the record does not state how individual assessment periods varied or how events outside that interval were handled.

The crystalloid-arm description ends before the phenylephrine infusion stopping point is complete. The record therefore does not fully document that element of the comparator regimen. It also does not report whether the fluid regimens and other co-interventions were implemented consistently or whether deviations occurred.

Primary outcome results list 37.0 participants per arm, while adverse-event reporting lists 41 at risk per arm. The registry record does not reconcile the denominators. Participant flow, withdrawals, exclusions, missing outcome data, and analysis populations are not reported, so the completeness of the analyzed groups cannot be assessed.

The record does not report the randomization sequence method, allocation concealment, outcome-assessor masking, a statistical analysis plan, or a multiplicity strategy. It lists fetal cord blood pH and APGAR scores as secondary outcomes but provides no results for them. The adverse-event summary has zero affected for the listed categories, but deaths and detailed event definitions are not reported. These gaps limit evaluation of trial conduct, reporting completeness, and the scope of conclusions; they do not by themselves demonstrate that bias or safety problems occurred.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Spinal Anesthesia Induced Hypotension During Cesarean Section — NCT00846651.
• Registry record last updated 2017-10-16; status last verified 2017-09.
• Results first posted 2013-07-03.
• 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.

22. Record Summary

The registry record describes a completed, phase 4, randomized, unmasked, parallel-group trial sponsored by Milton S. Hershey Medical Center. Enrollment is listed as 82; the recorded start and primary completion dates are 2009-02 and 2009-12.

The trial compared colloid or crystalloid fluid administration followed by phenylephrine infusion during cesarean section with spinal anesthesia. The primary outcome was maternal hypotension incidence over an average assessment period of 20 min. The posted group percentages were 10.8% and 27.0%, respectively, with an unadjusted risk difference of 0.162 and a confidence interval from -0.012 to 0.337.

The interval includes no difference, and the result remains uncertain. The record does not report the hypotension definition, analysis populations, missing-data methods, or multiplicity approach. Results for two listed secondary outcomes are not reported in the registry record.