Gastric Ultrasound Versus Gastroscopic Aspiration (GUSGA)

December 18, 2025 updated by: Abdouli Hadhami, Hôpital Fribourgeois

Diagnostic Performance of Preoperative Gastric Ultrasound Compared to Gastroscopic Aspiration: A Prospective Clinical Study

This is a prospective, single-center observational study conducted at the Fribourg Cantonal Hospital to evaluate the diagnostic performance of preoperative gastric ultrasound in determining gastric content and volume. Upper gastrointestinal endoscopy with complete suction of gastric contents serves as the reference standard.

Adult patients (≥ 18 years) scheduled for elective or urgent gastroscopy are consecutively recruited. A gastric ultrasound is performed within one hour before the endoscopic procedure. The antral cross-sectional area is measured in standardized positions (supine and right lateral decubitus), and gastric volume is estimated using validated formulas. Gastric content is categorized into three grades (empty, low-risk liquid content, or high-risk/solid content).

During gastroscopy, complete aspiration of gastric contents is performed at the start of the procedure. The aspirated volume and qualitative characteristics (liquid vs. solid) are recorded, and the stomach is classified as empty, partially full, or full by the endoscopist.

The primary objective is to determine the accuracy of gastric ultrasound in identifying a full stomach. Secondary objectives include evaluating the qualitative agreement between ultrasound and gastroscopy, correlating estimated gastric volume with aspirated volume, and identifying an optimal ultrasound-based volume threshold predictive of a full stomach.

Approximately 1,390 patients will be enrolled over one year to obtain at least 139 "full stomach" cases, based on prevalence estimates and sample size calculations. Statistical analyses will include diagnostic performance metrics, Cohen's kappa, correlation tests, Bland-Altman plots, and ROC curve analysis.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Study Procedure and Conduct Each participant enrolled in the study will undergo a standardized two-step assessment protocol, consisting of a preoperative gastric ultrasound followed by a gastroscopy with complete aspiration of gastric contents. These procedures will be performed within a maximum interval of one hour, and conducted at Fribourg Cantonal Hospital within the Departments of Anesthesiology and Gastroenterology. All examinations will be performed by trained and credentialed operators, adhering to validated clinical protocols.

Following the acquisition of written informed consent, baseline demographic and clinical data will be collected. Gastric ultrasound will then be performed using a portable ultrasound device equipped with a low-frequency curvilinear transducer. The patient will be positioned sequentially in the supine and right lateral decubitus positions, with the upper body inclined at 45°, to obtain sagittal views of the gastric antrum. Antral diameters (antero-posterior and cranio-caudal) will be measured in each position, and the cross-sectional antral area (CSA) will be calculated accordingly. The estimated gastric volume (EGV) will be derived using the validated formula proposed by Perlas et al. Gastric contents will be classified into three qualitative grades (Grade 0 to 2), enabling stratification of aspiration risk.

Within one hour of the ultrasound, a diagnostic gastroscopy will be performed by an experienced gastroenterologist, following routine clinical practice. Immediately upon endoscope insertion and prior to any irrigation, complete aspiration of gastric contents will be performed to allow accurate measurement of the intragastric volume. The contents will be assessed macroscopically for appearance (e.g., clear, cloudy, bilious, alimentary) and consistency (liquid or solid). The aspirated volume will be quantified using a calibrated, graduated container. Based on visual assessment, the stomach will be classified as empty, partially full, or full.

All collected data will be documented using standardized case report forms and entered into a secure, anonymized database for subsequent statistical analysis.

Study Type

Interventional

Enrollment (Estimated)

1390

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Adults aged ≥ 18 years
  • Indication for gastroscopy (scheduled or urgent), allowing complete aspiration of gastric contents
  • Feasibility of performing gastric ultrasound within one hour prior to the endoscopic procedure
  • Provision of written informed consent

Exclusion Criteria:

  • Pregnancy
  • History of major gastric or esophageal surgery
  • Known disorders of gastric emptying (e.g., gastroparesis, gastric outlet obstruction)
  • Cognitive impairment or language barriers preventing understanding of the study protocol
  • Active vomiting or technical impossibility to aspirate gastric contents

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: Gastric Ultrasound and Gastroscopy
Single Group - Diagnostic Assessment
Diagnostic test: Gastric Ultrasound
All enrolled participants undergo a preoperative gastric ultrasound within one hour prior to the scheduled gastroscopy. The gastric antrum is measured in standardized positions, and estimated gastric volume is calculated.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
the diagnostic accuracy of gastric ultrasound in identifying a full stomach, using gastroscopy with aspiration as the reference standard.
Time Frame: Within 1 hour prior to gastroscopy
Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy of preoperative gastric ultrasound in identifying a full stomach, compared to gastroscopy with complete aspiration of gastric contents. Gastric content is classified as empty, low-risk liquid content, or high-risk/solid content.
Within 1 hour prior to gastroscopy

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Optimal estimated gastric volume (EGV) threshold for predicting a full stomach
Time Frame: Within 1 hour prior to gastroscopy
Determination of the optimal threshold of estimated gastric volume (EGV) measured by preoperative ultrasound for predicting a full stomach, using receiver operating characteristic (ROC) curve analysis. Sensitivity, specificity, and area under the ROC curve (AUC) will be calculated.
Within 1 hour prior to gastroscopy
Correlation coefficient between ultrasound-estimated gastric volume and aspirated gastric content volume during gastroscopy
Time Frame: Within 1 hour prior to gastroscopy
Gastric volume is estimated by preoperative ultrasound and compared with the volume of gastric content aspirated during gastroscopy. The Pearson or Spearman correlation coefficient is calculated depending on data distribution.
Within 1 hour prior to gastroscopy
Cohen's kappa coefficient for agreement between ultrasound and gastroscopy regarding gastric content nature
Time Frame: Within 1 hour prior to gastroscopy
Agreement between gastric ultrasound and gastroscopy for classification of gastric content nature (clear liquid, turbid liquid, solid) is assessed using Cohen's kappa coefficient.
Within 1 hour prior to gastroscopy

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hôpital Fribourgeois

Investigators

  • Principal Investigator: Hadhami Abdouli, Docteur, Hôpital Cantonal Fribourgeois

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

February 1, 2026

Primary Completion (Estimated)

January 31, 2027

Study Completion (Estimated)

January 31, 2027

Study Registration Dates

First Submitted

December 6, 2025

First Submitted That Met QC Criteria

December 6, 2025

First Posted (Estimated)

December 18, 2025

Study Record Updates

Last Update Posted (Actual)

December 24, 2025

Last Update Submitted That Met QC Criteria

December 18, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • GUSGA-2025

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

The shared individual participant data (IPD) will include only the data used in the publication of the study results, specifically:

  • Gastric ultrasound measurements (antral cross-sectional area, estimated gastric volume, gastric content grade)
  • Gastroscopy findings (aspirated gastric volume, qualitative gastric content classification)
  • Basic participant characteristics (age, sex, weight)

IPD Sharing Time Frame

Starte Date: After publication of the study results End Date: 5 years after publication

IPD Sharing Access Criteria

Researchers who submit a reasonable request for research purposes. Requests should be sent via email to the corresponding author. Access will be granted only after the request has been reviewed and approved by the study team.

All shared data will be anonymized to protect participant confidentiality. The data and documents can be used solely for scientific research, and recipients are expected not to attempt to identify individual participants.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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