Diagnostic Accuracy of Using Point-of-care Ultrasonography for Confirming Nasogastric Tube Placement

July 4, 2025 updated by: Mak Mei Yi, Pamela Youde Nethersole Eastern Hospital

Diagnostic Accuracy of Using Point-of-care Ultrasonography for Confirming Nasogastric Tube Placement: a Multicentre Prospective Study

A prospective observational diagnostic study will be conducted to assess the sensitivity and specificity of ultrasound in verifying the correct nasogastric tube placement, using X-ray as the reference standard.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

This study is a prospective observational diagnostic investigation aimed at evaluating the accuracy of ultrasound in confirming nasogastric tube (NGT) placement. Participants aged 18 years or older requiring NGT insertion will be recruited via convenience sampling from community nursing centres across five clusters and medical and geriatric wards in four acute or convalescent hospitals. Nurses performing index tests will complete standardized POCUS training (8-hour theory and practical sessions, written exams, 3-month bedside practicum with ≥20 positive scans) prior to competency assessment. Direct visualisation of an NGT in both the oesophagus and stomach will be interpreted as correct stomach placement. When the acoustic shadow of an NGT was not seen in the stomach, 50cc of air was injected through the NGT, and it was considered well-placed if the ultrasonography showed dynamic fogging. Correct gastric placement is assumed if the acoustic shadow of an NGT is visible in the oesophagus and stomach, even if fogging is not detectable. The reference standard will be post-index test X-ray confirmation. Diagnostic performance metrics, including sensitivity, specificity, positive and negative predictive values, and likelihood ratios, will be calculated to assess the efficacy of ultrasound. Variability in diagnostic accuracy across participant characteristics will be analyzed. Additionally, the study will compare the time intervals between ultrasound and X-ray, delays in feeding initiation post-placement, and associated costs, including emergency department admissions, unplanned hospitalizations, and ambulance transportation.

The findings will provide critical evidence on the diagnostic utility of ultrasound for NGT placement verification, informing potential revisions to clinical practice guidelines and supporting stakeholder decisions on integrating ultrasound as a reference test.

Study Type

Observational

Enrollment (Estimated)

530

Contacts and Locations

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

Study Locations

  • Hong Kong
      • Hong Kong, Hong Kong
        • Hospital Authority, HKSAR

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

Sampling Method

Non-Probability Sample

Study Population

Convenience sampling will be adopted in this study. Participants will be recruited from six community nursing centres in Hong Kong East, Hong Kong West, Kowloon Central, Kowloon West, and New Territories West Cluster hospitals, as well as 38 wards from medical and geriatric wards across 4 acute, rehabilitation or convalescent hospitals managed by the Hospital Authority. Participants will be engaged by episodes throughout the study.

Description

Inclusion Criteria:

  • Aged 18 or older;
  • Living in the community or admitted to a medical and geriatric ward;
  • Requiring the use of an NGT during the recruitment period for assessment, monitoring, nutritional assistance, drainage, and/or medication administration;
  • Aspirated fluids with a pH value of more than 5.5 after insertion or with insufficient fluids for pH testing after insertion;

Exclusion Criteria:

  • Uncooperative patients;
  • Had head and neck injury
  • Have had a gastrectomy or by-pass surgery;
  • History of abdominal trauma or receiving emergency life support intervention at time of recruitment.

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

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Observational Group
All participants included will be in one observational cohort.
Device: Diagnostic ultrasound
A portable wireless ultrasound system (Vscan Air, General Electric Healthcare) with dual probes-linear array (3-12 MHz) for neck scanning and curved array (2-5 MHz) for subxiphoid scanning-will be used. The linear probe is placed transversely on the anterior neck, slid left at the thyroid level to focus on the esophagus, then rotated for longitudinal views. The curved probe is applied subxiphoid, using the liver as a landmark, and tilted left to image the stomach. A positive result is confirmed by visualizing the NGT shadow in the esophagus and stomach, followed by dynamic upsurge fogging after injecting 50cc of air. Ultrasonography and X-ray results will be compared.
Device: Diagnostic X-ray
This study will employ chest radiography as the reference standard for verification of correct nasogastric tube placement. Radiographic imaging will be conducted following NGT insertion and interpreted by physicians to verify positional accuracy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Diagnostic Accuracy of Ultrasound in correct Nasogastric Tube placement confirmation
Time Frame: An average of 18 months
Sensitivity: True Positive / (True Positive + False Negative) x 100% Specificity: True Negative / (True Negative + False Positive) x 100% Positive Predictive Value: True Positive / (True Positive + False Positive) x 100% Negative Predictive Value: True Negative / (True Negative + False Negative) x 100% Positive Likelihood Ratio: sensitivity / 1 - specificity Negative Likelihood Ratio: 1 - sensitivity / specificity
An average of 18 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Time lag between USG & x-ray
Time Frame: An average of 18 months
The study will assess the time lag between ultrasound confirmation and subsequent X-ray imaging for nasogastric tube placement verification.
An average of 18 months
Delay between tube placement and feeding by x-ray
Time Frame: An average of 18 months
The study will evaluate the delay between nasogastric tube placement and the initiation of feeding, as confirmed by X-ray.
An average of 18 months
Cost of ED admission, unplanned admission, ambulance transportation
Time Frame: An average of 18 months
The study will analyze costs associated with Emergency Department admissions, unplanned hospital admissions, and ambulance transportation related to nasogastric tube placement confirmation.
An average of 18 months

Collaborators and Investigators

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

Sponsor

Pamela Youde Nethersole Eastern Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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 (Actual)

April 28, 2025

Primary Completion (Estimated)

October 1, 2026

Study Completion (Estimated)

October 1, 2028

Study Registration Dates

First Submitted

February 6, 2025

First Submitted That Met QC Criteria

February 6, 2025

First Posted (Actual)

February 12, 2025

Study Record Updates

Last Update Posted (Actual)

July 9, 2025

Last Update Submitted That Met QC Criteria

July 4, 2025

Last Verified

July 1, 2025

More Information

Terms related to this study

Other Study ID Numbers

  • CIRB-2024-467-2

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The datasets generated and/or analyzed during this study will be made available by the principal investigator upon reasonable request.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

Yes

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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