Korean consensus-based recommendations for preanesthetic gastric ultrasound and anesthetic considerations for GLP-1 receptor agonist–based therapy: a consensus statement from Clinical Practice Guideline Committee of the Korean Society of Anesthesiologists

Abstract

Pulmonary aspiration during anesthesia remains an uncommon but clinically significant perioperative complication associated with substantial morbidity and mortality. Although contemporary fasting guidelines recommend minimum fasting intervals to reduce aspiration risk, adherence does not guarantee an empty stomach, particularly in patients with delayed gastric emptying or those receiving medications that impair gastrointestinal motility, such as glucagon-like peptide-1 receptor agonist (GLP-1 RA)–based therapies. Preanesthetic gastric ultrasound has emerged as a practical point-of-care modality for the qualitative and quantitative assessment of gastric content and volume, enabling individualized aspiration risk stratification in selected patients. However, the current evidence base remains insufficient to formally support evidence-graded clinical practice guidelines. The consensus-based recommendations presented in this guideline were developed through expert discussion and review of the available literature, in which robust evidence is lacking. They provide practical guidance on the indications for preanesthetic gastric ultrasound, core examination principles and interpretation, integration of ultrasound findings into perioperative decision-making, management when gastric ultrasound is not feasible, and anesthetic strategies for patients with a full stomach. Special recommendations are included for patients receiving GLP-1 RA–based therapies, emphasizing the continuation of these medications in most patients with individualized risk assessment, consideration of a 24-h clear liquid diet, and the use of gastric ultrasound when delayed gastric emptying is suspected. Preanesthetic gastric ultrasound provides a practical bedside method for assessing gastric content and estimating aspiration risk in patients undergoing anesthesia. These recommendations are intended to support, not replace, clinical judgment and should be refined through future prospective outcome-based studies.

Introduction

Pulmonary aspiration of gastric contents remains one of the most serious complications of anesthetic practice [1]. Although its incidence is very low, the associated morbidity and mortality rates are substantial [2]. Traditional preventive strategies focus on preoperative fasting policies and risk stratification based on patient- and procedure-related factors. Fasting recommendations, including those proposed by the American Society of Anesthesiologists (ASA), define the minimum fasting intervals intended to mitigate the aspiration risk in the surgical population [3]. However, these interval-based recommendations are not designed to determine an individual patient’s actual gastric content or volume at the time of anesthetic induction.

In clinical practice, situations frequently arise in which fasting status is uncertain, gastric emptying may be delayed, or the urgency of surgery precludes adherence to standard fasting intervals [4]. Moreover, several clinical factors, including diabetes mellitus, obesity, gastrointestinal motility disorders, opioid exposure, pregnancy, trauma, and emergency surgical conditions, are associated with variable or unpredictable gastric contents despite reported compliance with fasting instructions [5–11]. In recent years, the widespread use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) for the management of type 2 diabetes mellitus and obesity has further heightened attention to pharmacologically induced delays in gastric emptying [12,13].

Point-of-care gastric ultrasound enables the qualitative and quantitative assessment of gastric content and volume through visualization of the gastric antrum [14,15]. Over the past decade, increasing evidence has demonstrated its feasibility, reproducibility, and potential utility in perioperative settings. By providing real-time information regarding gastric contents, preanesthetic gastric ultrasound may assist clinicians in tailoring airway management strategies, determining the appropriateness of proceeding with surgery, and implementing risk mitigation measures when a full stomach is suspected.

However, high-quality outcome-based data are scarce. Most available studies have focused on the diagnostic performance of surrogate measures of gastric volume rather than on clinically meaningful aspiration outcomes. Consequently, uncertainty persists regarding the optimal indications, standardized methodology, and integration of gastric ultrasound findings into perioperative anesthetic decision-making.

Given these considerations, an expert group convened to review the current literature and clinical experience and develop consensus-based recommendations regarding the use of preanesthetic gastric ultrasound, including specific recommendations for patients receiving GLP-1 RA–based therapies. This manuscript presents an expert consensus statement informed by the best available evidence at the time of writing, intended to provide practical guidance to clinicians while acknowledging the limitations of the current evidence. These recommendations aim to support clinical decision-making and enhance patient safety in real-world perioperative settings. They do not replace individualized clinical judgment or establish mandatory standards of care. Ongoing research and prospective outcome studies are required to further refine and validate these recommendations. 

Methods

Development process and scope

This consensus statement was developed by members of the Clinical Practice Guideline Committee of the Korean Society of Anesthesiologists (KSA). A total of 22 experts were invited to participate in a Delphi survey. The expert panel comprised 21 members of the Clinical Practice Guideline Committee of the KSA and the Chair of the Academic Committee; all were board-certified anesthesiologists with clinical and academic expertise relevant to perioperative care, airway management, and point-of-care ultrasound and were nominated by the KSA as specialists in their fields. The objective of this guideline was to provide practical recommendations regarding the use of preanesthetic gastric ultrasound in adult patients undergoing anesthesia and to address perioperative considerations for patients receiving GLP-1 RA–based therapies.

The scope of this document includes fundamental scanning techniques, preferred indications for gastric ultrasound, clinical decision-making regarding whether to proceed with surgery based on ultrasound findings, management strategies when gastric ultrasound is not feasible, perioperative anesthesia management in patients suspected of having a full stomach, and special considerations for patients receiving GLP-1 RA–based therapies. Pediatric patients were not included in the formal Delphi consensus process; content pertaining to pediatric populations was included only for background and contextual purposes.

Literature review

A structured literature search was conducted through March 2026 using major medical databases including PubMed, Embase, and the Cochrane Library. The search covered two main areas: (1) preanesthetic gastric ultrasound, including studies evaluating feasibility, reproducibility, qualitative grading systems, gastric volume estimation models, and clinical applications, and (2) perioperative considerations for patients receiving GLP-1 RA–based therapies. Observational studies, randomized controlled trials, systematic reviews, and expert reports were considered.

Given the heterogeneity of the available studies and the limited number of high-quality outcome-based trials, formal evidence grading was not consistently applicable. Therefore, the available literature was synthesized along with expert clinical experience to inform the recommendations.

Consensus process

Preliminary statements were drafted based on the literature review and expert input. These statements were discussed during structured committee meetings and revised iteratively. A consensus was established using a modified Delphi process with a 4-point Likert scale (strongly disagree, disagree, agree, and strongly agree) or an option to suggest revisions. Recommendations with ≥75% agreement (agree or strongly agree) were carried forward unchanged to the second round. Recommendations with 50%–74% agreement were revised based on participant feedback and resubmitted for further evaluation, whereas those with <50% agreement were excluded from further consideration.

Of the 22 invited experts, 19 completed both the first and second rounds, corresponding to a response rate of 86.4% (19/22). After each Delphi round, the survey responses and comments were summarized and reviewed. The recommendation statements were revised based on panel feedback before being redistributed in subsequent rounds. Final recommendations were established after completing the second Delphi round and achieving the predefined consensus threshold. To enhance transparency regarding the level of consensus achieved, the final agreement rate for each recommendation is presented in Supplementary Table 1. The final recommendations were reviewed and approved by the Clinical Practice Guideline Committee of the KSA (Chairman, Bon-Nyeo Koo). The recommendations are summarized in Box 1.

Box 1. Recommendations for Preanesthetic Gastric Ultrasound and Management of GLP-1 RA–based Therapy

Indication and Performance of the Examination

1. Preanesthetic gastric ultrasound may be considered in selected patients with uncertain fasting status or those at risk of delayed gastric emptying.

2. Gastric ultrasound should be performed using a standardized technique based on identification of the gastric antrum, with the supine and right lateral decubitus positions as standard positions.

Interpretation, Clinical Decision-Making, and Training

3. Interpretation of gastric ultrasound begins with a qualitative assessment, followed by quantitative estimation when increased gastric volume is suspected. In general, an estimated gastric volume greater than 1.5 mL/kg may indicate an increased risk of pulmonary aspiration.

4. If gastric ultrasound is not feasible or yields inconclusive findings, this should not be interpreted as evidence of an empty stomach; clinical decision-making should be based on an integrated assessment of aspiration risk.

5. Final decisions to proceed with, delay, or cancel surgery should be determined not only by preoperative gastric ultrasound findings but also by the overall clinical context, including surgical urgency, patient comorbidities, fasting history, institutional resources, and shared decision-making among the anesthesiologist, surgical team, and patient.

6. When a full stomach is identified or aspiration risk remains uncertain, perioperative management should include aspiration risk mitigation strategies. These may include pharmacologic interventions, nasogastric tube insertion, rapid sequence induction, ramped positioning, or regional anesthesia, as appropriate to the clinical situation.

7. Gastric ultrasound training includes image acquisition, measurement, interpretation, and clinical application, with competency achieved through supervised practice.

Special Consideration: Management of Patients Receiving GLP-1 RA–based Therapy

8. In most patients receiving GLP-1 RA–based therapies, routine discontinuation is not recommended, and continuation may be appropriate in low-risk patients. The decision to continue or withhold the medication should be individualized according to clinical risk factors, including gastrointestinal symptoms (nausea, vomiting, dyspepsia, or abdominal bloating), recent dose escalation, use of high-dose or long-acting formulations, treatment duration, obesity, and diabetes mellitus.

9. A 24-h clear liquid diet followed by standard preoperative fasting may be recommended for patients receiving GLP-1 RA–based therapies.

10. In patients receiving GLP-1 RA–based therapies who have symptoms suggestive of delayed gastric emptying or have not completed the 24-h clear liquid diet, preoperative gastric ultrasound may be used, where available, to guide the anesthetic approach.

Gastric ultrasound examination

Fundamentals of gastric ultrasound

Gastric sonoanatomy

(1) Antral location and anatomical landmarks

Preanesthetic gastric ultrasound is centered on the reproducible identification of the gastric antrum, the portion of the stomach most consistently visualized using transabdominal ultrasound, and the segment demonstrating the strongest correlation with total gastric volume [14,16–19]. Among all gastric regions, the antrum has been shown to be the most amenable to sonographic examination, with reported identification rates of approximately 98%–100% in adults [17,19]. The antrum is located in the epigastrium, anterior to the pancreas and posterior to the left lobe of the liver that provides an acoustic window. In the sagittal or right parasagittal plane, the abdominal aorta and superior mesenteric artery serve as reproducible posterior landmarks that standardize the scanning level (Fig. 1).

Fig. 1.

Identification of the gastric antrum for preanesthetic gastric ultrasound. (A) Probe placement for gastric ultrasound. A low-frequency curvilinear transducer is positioned in the epigastric region in a sagittal or slightly right parasagittal orientation to visualize the gastric antrum. (B) Schematic representation of the upper abdomen corresponding to the ultrasound plane indicated by the green line. (C) Representative ultrasound image of the gastric antrum obtained in the right lateral decubitus position. The antrum appears as a round or ovoid structure between the left lobe of the liver and the pancreas. A: antrum, Ao: aorta, SMA: superior mesenteric artery.

(2) Sonographic appearance of the gastric wall

On ultrasound, the gastric wall demonstrates the characteristic “gut signature” common to the gastrointestinal tract. Although histologically composed of five layers [17–19], ultrasonography in adults, typically performed using a low-frequency curvilinear probe, usually depicts a three-layer pattern: an inner echogenic layer representing the mucosa and submucosa, a hypoechoic middle layer corresponding to the muscularis propria, and an outer echogenic layer formed by the serosa and surrounding fat. This layered appearance confirms the gastrointestinal origin, but is not specific to the stomach. Therefore, differentiation from the adjacent hollow viscera relies on the anatomical location and dynamic characteristics, as discussed below.

Quantitative assessment requires measurement of the antral cross-sectional area (CSA) from serosa to serosa, as validated mathematical models for gastric volume estimation are based on full-thickness measurement [14,16,17,19,20]. Therefore, the accurate identification of the outer hyperechoic serosal boundary is essential to ensure reliable volume estimation.

Gastric ultrasound scan acquisition

The technique described here reflects the established scanning methodology used in most validation studies in adult and pediatric populations (Supplementary Videos 1 and 2). Gastric ultrasound is performed using a low-frequency curvilinear transducer (2–5 MHz) that provides adequate penetration for identification of the posterior gastric wall and key vascular landmarks.

The probe is positioned in the epigastrium immediately inferior to the xiphoid process in a sagittal or slight right parasagittal orientation with the marker directed cephalad (Fig. 1A) [21]. Image optimization requires appropriate probe angulation to align the ultrasound beam through the left lobe of the liver that serves as an acoustic window and facilitates posterior visualization of the gastric antrum (Figs. 1B and C). To obtain a standardized short-axis view of the antrum, the probe is adjusted slightly until the descending abdominal aorta is visualized along the long axis posterior to the antrum. In some individuals, the superior mesenteric artery may also be identified along the long axis to confirm correct alignment of the scanning plane.

Imaging is performed sequentially in a nondependent position (supine or semi-recumbent), followed by a right lateral decubitus (RLD) position. Initial assessment in the supine position allows for a global qualitative evaluation of the gastric content and facilitates the identification of solid or high-volume liquid content. However, small volumes of fluid may not be reliably detected in nondependent positions.

For quantitative assessment, imaging should be repeated in the RLD position. Established quantitative models correlating the antral CSA with the gastric volume are based on measurements obtained in RLD [16]. The RLD position increases the sensitivity for detecting small volumes of fluid. Owing to gravitational redistribution, liquid and semi-liquid gastric contents move toward the dependent antrum, whereas intragastric air is displaced proximally toward the gastric body and fundus [14,17,22]. This redistribution enhances antral distension and optimizes scanning conditions, particularly in low-volume states in which fluid may not be visible in the supine position.

The antral CSA must be measured during the resting phase between peristaltic contractions when the antrum is maximally distended. Measurements obtained during active contraction may result in a systematic underestimation of gastric volume. The CSA may be determined either by using the free-tracing tools available on ultrasound machines to outline the serosal border directly (Fig. 2A) or by measuring two orthogonal diameters from serosa to serosa and applying the formula for the area of an ellipse (Fig. 2B). Validated mathematical models for gastric volume estimation are subsequently applied to the measured CSA (see Interpretation: Quantitative estimation). The mean of three consecutive measurements obtained between contractions is recommended to enhance reproducibility.

Fig. 2.

Methods for measuring the antral cross-sectional area (CSA). (A) Measurement of the antral CSA using the free-tracing method. The dotted outline indicates the manually traced outer serosal border of the gastric antrum and represents the measured CSA. (B) Measurement of the antral CSA using the two-diameter method. The caliper markers identify the two orthogonal diameters of the gastric antrum: the anteroposterior (AP) diameter (+ markers) and the craniocaudal (CC) diameter (× markers). Both are measured from outer serosa to outer serosa, and CSA is calculated using the ellipse formula: CSA = (AP × CC × π) / 4. Ao: aorta, SMA: superior mesenteric artery.

Although the acquisition technique is fundamentally similar across populations, specific considerations were applied. In older patients, increasing age has been independently associated with prolonged examination times and greater technical difficulty [23]. Reduced mobility, kyphosis, discomfort during repositioning, and diminished tolerance to RLD may limit examination completeness [22,23]. When proper positioning is not feasible, assessment in the semi-recumbent position may serve as a practical alternative for qualitative evaluation and partial quantitative estimation. However, most validated quantitative models are derived from RLD measurements; therefore, interpretations should be made with caution. In pediatric patients, a high-frequency linear transducer may provide improved resolution in smaller children (approximately <30–40 kg), whereas a curvilinear probe is appropriate for larger children and the same serosa-to-serosa measurement principle is applied [19]. In late pregnancy, supine positioning should be avoided because of aortocaval compression [24]; instead, scanning is recommended in a 45° semi-recumbent position followed by semi-recumbent RLD positioning, with pregnancy-specific quantitative models applied when appropriate [25].

Anatomic pitfalls in gastric ultrasound

Because the multilayered “gut signature” is shared by other hollow viscera, definitive identification of the gastric antrum requires integration of anatomical location, surrounding landmarks, wall morphology, luminal characteristics, and dynamic contractile behavior. Several upper abdominal structures may mimic the antrum during focused gastric ultrasound examination.

In the fasting state, the gastric wall is typically thicker (approximately 4–6 mm) than the small bowel, and the antrum demonstrates intermittent coordinated peristaltic contractions separated by resting phases. These dynamic features help distinguish the antrum from the adjacent bowel loops, particularly in low-volume states when only small amounts of clear fluid are present. With increasing intraluminal content, the antrum becomes distended, and its luminal echogenicity varies according to whether clear fluid, thick fluid, or solid material is present. Marked distension or heterogeneous intraluminal content may distort the typical morphology and occasionally make discrimination between adjacent structures more challenging [26].

Accurate gastric volume estimation depends on unequivocal acquisition at the true antral level. Adjacent structure measurement may lead to inaccurate interpretation and erroneous risk stratification [26]. Therefore, the definitive identification of the gastric antrum requires consistent visualization between the left lobe of the liver anteriorly and the pancreas posteriorly, confirmation of its location at the level of the abdominal aorta, and recognition of its characteristic intermittent contractile pattern. Once an antral view is established, brief scanning in adjacent planes to confirm continuity with the pylorus and proximal duodenum may further reinforce correct anatomical localization and increase operator confidence.

Interpretation of gastric ultrasound

Initial assessment in the supine or semi-recumbent position provides a qualitative overview of the gastric contents, after which the examination is repeated in the RLD position to refine the classification and enable quantitative estimation when required.

(1) Qualitative assessment

Qualitative assessment begins with careful evaluation of the sonographic appearance of the antrum under different states of gastric content. Morphological interpretation precedes the application of formal grading systems.

In the fasting state, the gastric antrum appears small and flat with juxtaposition of the anterior and posterior walls, producing the classic “bull’s eye” or target sign. The wall layers are closely apposed and the posterior wall is clearly delineated (Fig. 3A).

Fig. 3.

Sonographic appearance of the gastric antrum according to gastric content. (A) Fasting state: The antrum appears small and flattened, with apposition of the anterior and posterior walls, producing the classic “bull’s eye” (target) sign. (B) Clear liquid: The antrum is distended and contains uniformly anechoic fluid with posterior acoustic enhancement. Small intraluminal hyperechoic foci may be visible when air is intermixed (“starry” appearance). (C) High-viscosity liquid (milk): The antrum is distended and contains relatively homogeneous echogenic fluid, lacking the uniformly anechoic pattern of simple clear liquid. (D) Solid contents, early phase: Diffuse echogenic “frosted-glass” appearance caused by ring-down artifacts at the mucosal–air interface, often obscuring posterior structures. (E) Solid contents, late phase: Heterogeneous particulate intraluminal material following redistribution or dissipation of intragastric air. A: antrum, Ao: aorta, SMA: superior mesenteric artery.

When clear fluid is present, the antrum becomes distended, and the lumen appears uniformly anechoic, with clear visualization of the posterior gastric wall. Posterior acoustic enhancement is typically observed due to the fluid-filled lumen (Fig. 3B). If small amounts of air are intermixed with the fluid—such as immediately after ingestion—scattered hyperechoic foci may be seen within the anechoic lumen, producing a transient “starry” or “starry-sky” appearance. In contrast, high-viscosity liquids, such as milk, appear more homogeneously echogenic, making them readily distinguishable from simple clear liquids (Fig. 3C).

Following the ingestion of solid food, the sonographic appearance differs substantially from that of a clear liquid. Immediately after a solid meal, the swallowed air is frequently interposed between the mucosa, liquid, and particulate material, resulting in a diffuse echogenic “frosted-glass” or “ground-glass” appearance caused by ring-down artifacts at the mucosal–air interface. In the early phase, the posterior structures may be partially or completely obscured (Fig. 3D). As intragastric air redistributes or dissipates over time, the pattern may evolve into a clearer particulate configuration characterized by heterogeneous echogenic material (Fig. 3E). At this stage, the antrum is typically distended and wall layering may be less sharply defined than in the fasting state.

Following morphological assessment, qualitative assessment may be structured using the Perlas grading system that categorizes findings according to the presence or absence of clear fluid in the supine and RLD positions [19,21,27–29]. Grade 0 corresponds to the absence of fluid in both positions and is generally associated with low aspiration risk. Grade 1 describes fluid that is not visible in the supine position but becomes apparent in RLD and is usually associated with low risk. However, quantitative estimation may be warranted when clinical uncertainty exists to determine whether the gastric volume exceeds the accepted risk thresholds. Grade 2 denotes clear fluid visible in both the supine and RLD positions and is generally considered consistent with increased aspiration risk. When solid or thick particulate content is visualized, quantitative measurement is unnecessary because the presence of solid material alone is sufficient to classify the stomach as full. This grading framework provides a structured approach for qualitative interpretation and guides the need for subsequent quantitative estimation (Table 1).

Table 1.

Qualitative Classification of Gastric Content Based on the Perlas Grading System

Grade	Antral presentation	Volume implication	Aspiration risk
Grade 0	Empty in both the supine and RLD positions	Minimal	Low
Grade 1	Empty in the supine position; clear fluid visible only in the RLD position	Low-volume fluid, typically within baseline fasting range	Low
Grade 2	Clear fluid visible in both the supine and RLD positions	Increased gastric fluid volume	High

Adapted from gastricultrasound.org. Solid or thick gastric content in any position is always indicative of a full stomach and high aspiration risk, irrespective of the antral grade. RLD: right lateral decubitus.

(2) Quantitative estimation

When qualitative assessment suggests the possibility of clinically significant gastric content or when more precise risk stratification is required, quantitative estimation should be performed using validated adult prediction models.

In nonpregnant adults with normal gastric anatomy, the most widely adopted model is the Perlas model that was derived and validated against gastric suction–confirmed volumes [16]. This model estimates gastric volume from the antral CSA measured in the RLD position and incorporates patient age as follows:

Gastric Volume (mL)=27.0 + 14.6 × CSA (cm²) − 1.28 × age (years)

Given that the model was derived and validated in nonpregnant adults using RLD-measured CSA, the application of this equation to measurements obtained in nondependent positions or outside the validated population may lead to inaccurate volume estimation.

Even in strictly fasted low-risk individuals, a small amount of clear fluid is physiologically present because of the ongoing salivary and gastric secretions. Weight-adjusted baseline gastric volumes in elective surgical patients typically average approximately 0.4–0.6 mL/kg [14,16,19]. The upper limit of observed gastric volume in fasted elective surgical patients has been reported at approximately 1.5 mL/kg, corresponding to the 95th percentile of baseline volumes in individuals with an empty stomach [16]. For perioperative risk stratification, current consensus defines an estimated gastric volume ≥1.5 mL/kg, or the presence of solid content, as indicating increased aspiration risk [16,19,30]. The calculated RLD antral CSA values corresponding to a predicted gastric volume ≥1.5 mL/kg by age and body weight are summarized in Table 2. For a given predicted gastric volume, the corresponding antral CSA increases with advancing age.

Table 2.

Calculated RLD Antral CSA (cm²) Corresponding to a Predicted Gastric Volume ≥ 1.5 mL/kg by Age and Body Weight using the Perlas Model

Age (yr)	Body weight
	50 kg	60 kg	70 kg	80 kg	90 kg	100 kg
20	5.0	6.1	7.1	8.1	9.2	10.2
30	5.9	6.9	8.0	9.0	10.0	11.1
40	6.8	7.8	8.8	9.9	10.9	11.9
50	7.7	8.7	9.7	10.8	11.8	12.8
60	8.5	9.6	10.6	11.6	12.7	13.7
70	9.4	10.5	11.5	12.5	13.5	14.6
80	10.3	11.3	12.4	13.4	14.4	15.4

CSA values were calculated using the Perlas prediction model: V (mL) = 27.0 + 14.6 × CSA (cm²) − 1.28 × age (years). A gastric volume of 1.5 mL/kg is a pragmatic, model-derived threshold used to define increased gastric content [16]. All values are rounded for clinical applicability. RLD: right lateral decubitus, CSA: cross-sectional area.

Technical challenges and optimization strategies in gastric ultrasound

(1) Patient-related factors

Scan difficulty is not uniformly distributed across patient populations. Prospective observational data have demonstrated that male sex, increased body mass index, and advancing age are independently associated with greater technical difficulty and prolonged acquisition time [23]. Increased abdominal wall thickness and deeper antral locations in patients with higher body mass index may reduce acoustic penetration and obscure vascular landmarks [11]. In some male patients, voluntary or reflex abdominal wall tension may further limit adequate probe contact, making maintenance of consistent transducer alignment challenging [23]. In older individuals, reduced mobility, kyphosis, and intolerance to RLD positioning may compromise optimal acquisition. In pediatric patients, limited cooperation and motion artifacts frequently complicate imaging. RLD positioning may be impractical in a substantial proportion of children, particularly in emergency or acute care settings [31]. In such cases, supine or semi-recumbent assessments may be necessary. Short, repeated imaging attempts are often more successful than prolonged, single acquisitions in anxious or noncooperative children. Pregnancy presents additional patient-specific challenges. Cephalad displacement of the stomach by the gravid uterus increases the antral depth and alters the epigastric acoustic window. As supine positioning may be poorly tolerated in late gestation, examinations are typically performed in a 45° semi-recumbent position with RLD when feasible.

(2) Clinical factors

The clinical context also influences feasibility. In emergency and trauma settings, deviation from predefined scanning algorithms is more frequent, particularly in patients with a higher ASA physical status [23]. Immobilization devices, cervical spine precautions, pain, hemodynamic instability, or limited cooperation may prevent RLD repositioning, thereby reducing the sensitivity for detecting small volumes of the dependent fluid. In these situations, interpretation must integrate both sonographic findings and the overall clinical aspiration risk.

(3) Anatomical factors

Structural abnormalities of the upper gastrointestinal tract represent an additional limitation of antral-based assessments. Validated quantitative models were derived from patients with normal gastric anatomy. Prior upper gastrointestinal surgery, gastric tumors, significant hiatal hernia, or mechanical obstruction may alter the relationship between the antral CSA and total gastric volume. Under such circumstances, antral measurements may not reliably reflect global gastric content and the examination should be classified as indeterminate.

(4) Practical optimization strategies

Practical measures may improve acquisition under challenging conditions. Creating a calm environment, minimizing unnecessary exposure, and adjusting room lighting may reduce abdominal guarding and improve probe contact [32]. Interposed bowel gas or an overlying colon may occasionally obscure visualization of the gastric antrum, particularly in the supine position [26]. Manual displacement of the abdominal wall or graded transducer pressure may help redistribute bowel gas and enhance antrum identification [33]. Repositioning the patient, especially to RLD or semi-recumbent positions, may facilitate gravitational redistribution of gas and fluid. In some cases, a brief interval reassessment after several minutes allows spontaneous gas redistribution and improves visualization. In patients with obesity, requesting a brief inspiratory breath-hold may transiently improve the acoustic window and stabilize the abdominal wall [33]. In advanced pregnancy, examinations are typically performed in a semi-recumbent position because supine positioning may be poorly tolerated. Tachypnea may introduce motion artifacts; therefore, a brief coached breath-hold can improve image stability during acquisition. Gentle caudal displacement of the uterus and extension of the lower extremities may further enhance antrum visualization when the epigastric window is limited.

When adequate visualization cannot be achieved despite machine setting optimization, patient positioning, environmental factors, and repeat attempts, the examination should be documented as indeterminate rather than negative. In such cases, perioperative anesthetic management should favor conservative full-stomach precautions.

Training and competency in gastric ultrasound

Ultrasound examinations are generally considered operator dependent and require standardized education and formal assessment to ensure reliability. However, unlike many other ultrasound applications, gastric ultrasound targets a consistently identifiable antral landmark using a standardized acquisition technique. Consequently, competency can be achieved through structured training and supervised experience [34]. Learning curve analyses demonstrate relatively rapid skill acquisition and high interobserver agreement once basic proficiency is attained [35].

In developing an educational and competency assessment framework for preanesthetic gastric ultrasound, this consensus statement referred to the I-AIM (Indication, Acquisition, Interpretation, and Medical decision-making) framework as a structural foundation [30]. Competency extends beyond image acquisition and requires the integration of sonographic findings into clinical management. Indication requires appropriate patient selection and recognition of clinical scenarios in which gastric ultrasound meaningfully informs aspiration risk, including uncertain fasting status, high-risk comorbidities, altered gastrointestinal anatomy, and emergent surgical context. Acquisition requires the standardized identification of the gastric antrum, prioritization of RLD positioning when feasible, adherence to serosa-to-serosa measurement principles, and documentation of technically limited or indeterminate examinations. Interpretation requires the accurate application of qualitative grading, appropriate use of validated quantitative models within their defined limits, and the recognition of solid content or findings consistent with a full stomach. Medical decision-making requires the integration of ultrasound findings with the overall aspiration risk to guide airway management and perioperative planning.

Available learning-curve data suggest that qualitative reliability improves substantially after approximately 20–33 supervised examinations, with high agreement in grade discrimination reported after this range of experience [28,35,36]. In routine clinical practice, scan performance time continues to improve after basic training, with approximately 50 examinations suggested to achieve a stable baseline performance time (approximately 5 min) and proficiency [23]. Quantitative assessments, including reproducible CSA measurements and appropriate model applications, may require additional experience beyond that required for basic qualitative grading [37]. However, competency should not be defined solely by a fixed number of examinations. Structured training that includes supervised scanning across a range of gastric states, exposure to technically challenging patients, and formative feedback is recommended [38].

Indications for gastric ultrasound

Gastric ultrasound is not intended as a routine screening tool but rather as a bedside diagnostic assessment used for decision-making in situations of uncertain aspiration risk. Fasting history is frequently unreliable in several clinical situations and fasting duration alone does not reliably predict an empty stomach. Therefore, the use of gastric ultrasound is recommended in patients with an uncertain fasting status or in those at high risk of gastric retention, irrespective of the fasting duration (Table 3).

Table 3.

Clinical Situations in Which Gastric Ultrasound May Be Useful

Category	Clinical situations
Unknown or unreliable fasting status	Emergency surgery
	Reduced consciousness/cognitive impairment
	Uncertain oral intake history
Gastric emptying impairment	Acute gastrointestinal pathology associated with impaired gastric emptying (e.g., gastrointestinal obstruction or perforated viscus, ileus, appendicitis, acute cholecystitis, ischemic bowel)
	Upper gastrointestinal bleeding or active vomiting
Medical conditions associated with delayed gastric emptying	Diabetes mellitus
	End-stage renal disease
	Advanced liver disease
	Neuromuscular disorders (e.g., Parkinson’s disease, myotonic dystrophy)
Special populations	Pregnancy (especially labor or emergency cesarean delivery)
	Obesity
	Pediatric patients
Medication-related factors	GLP-1 RA–based therapy
Nutritional factors	Enteral feeding/uncertain caloric intake

GLP: glucagon-like peptide, RA: receptor agonist.

Unknown or unreliable fasting status

(1) Emergency surgery

In emergency surgical patients, gastric ultrasound studies have reported a high prevalence of “full stomach” at induction (approximately 18%–56%), and fasting duration was not correlated with full vs. empty stomach status [4,39]. Emergency settings have also been repeatedly identified as a major contributing factor in reported aspiration events [1,40].

(2) Reduced consciousness/cognitive impairment

Impaired consciousness is a well-recognized risk factor for pulmonary aspiration under anesthesia, largely due to unreliable fasting history and impaired airway protective reflexes. Many studies and major reviews have consistently identified altered mental status as a key aspiration risk factor [40,41].

(3) Patients with uncertain oral intake information

When fasting status is indeterminate (e.g., uncertainty regarding recent oral intake), gastric ultrasound can be used to identify patients with a “full stomach.”

Gastric emptying impairment

(1) Acute gastrointestinal pathology associated with impaired gastric emptying

Pulmonary aspiration of gastric contents is a major anesthetic concern in patients with intestinal obstruction or other acute intra-abdominal pathologies (e.g., perforated viscus, ileus, appendicitis, acute cholecystitis, or ischemic bowel), because these conditions may impair gastric emptying [42,43]. In aspiration-related closed-claim analyses, gastrointestinal obstruction and other acute abdominal pathologies were strongly associated with clinically significant aspiration events [42].

(2) Upper gastrointestinal bleeding or active vomiting

In a cohort study, aspiration pneumonia occurred in 4.8% (24/504) of patients undergoing endoscopic hemostasis for acute upper gastrointestinal bleeding, demonstrating a clinically relevant aspiration risk in this population [44]. In an incident-monitoring review of anesthesia-related events, aspiration episodes commonly occurred during induction and were frequently associated with regurgitation/vomiting mechanisms [1].

Medical conditions associated with delayed gastric emptying

Standard fasting may be unreliable in the following conditions:

(1) Diabetes mellitus (especially with autonomic neuropathy/gastroparesis)

In a prospective observational study of elective surgical patients with comparable fasting intervals, patients with diabetes had significantly higher ultrasound-estimated residual gastric volumes than non-diabetic controls, indicating that gastric contents may persist despite standard fasting [5].

(2) End-stage renal disease

In an ultrasound study assessing gastric emptying after a standardized meal, a substantial proportion of patients with end-stage renal disease still demonstrated Perlas grade 2 (significant gastric content) 6 h after a meal, consistent with delayed gastric emptying [6].

(3) Advanced liver disease

A scintigraphic study has demonstrated that patients with cirrhosis have a significantly prolonged gastric emptying half-time compared to controls, indicating frequent delayed gastric emptying in advanced liver disease [9].

(4) Neuromuscular disorders

A gastric emptying study has shown delayed gastric emptying in patients with Parkinson’s disease compared to controls, supporting a higher likelihood of gastric retention [7]. Likewise, studies on myotonic dystrophy have demonstrated abnormally delayed gastric emptying, even in the absence of prominent symptoms [8]. Therefore, gastric ultrasound may assist in risk stratification in these populations by providing an objective bedside assessment of gastric contents [5–9].

Special populations

(1) Pregnancy

Gastric ultrasound may be considered in obstetric patients at risk of aspiration, particularly during active labor, emergency cesarean delivery, and when general anesthesia is required. In laboring patients, gastric ultrasound studies have reported a high prevalence of “high-risk stomach,” suggesting that significant gastric contents may be present when general anesthesia becomes necessary [10].

(2) Obesity

Obesity alone is not an absolute indication for gastric ultrasound. However, in ultrasound studies, patients with obesity demonstrated larger fasting gastric volumes than normal-weight individuals [45,46]. These findings suggest that patients with obesity are less likely to have a completely empty stomach despite appropriate fasting, although most remain below the commonly accepted aspiration risk thresholds.

(3) Pediatric population

In infants and children, studies comparing gastric ultrasound findings with aspirated or endoscopically measured contents have shown that residual gastric contents may be present despite adherence to fasting recommendations, supporting the use of ultrasound when fasting history is uncertain or aspiration risk is clinically significant [20].

GLP-1 RA–based therapy

GLP-1 RA or dual GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) RA (GLP-1/GIP RA) use has been associated with increased residual gastric content before anesthesia in a large observational analysis [12]. A systematic review and meta-analysis of patients undergoing gastrointestinal endoscopy also reported higher odds of retained gastric contents among GLP-1 RA users, while rates of aspiration pneumonia were not significantly different, reinforcing the importance of assessing gastric contents in selected patients, particularly those with symptoms or recent dose escalation [13].

Enteral feeding or uncertain caloric intake

In critically ill patients receiving enteral nutrition, serial ultrasound assessments demonstrated measurable and clinically variable residual gastric volumes without interruption of enteral feeding, supporting the presence of residual gastric contents in this setting and the potential value of ultrasound when aspiration risk is a concern [47].

Clinical decision-making after preanesthetic gastric ultrasound

Preanesthetic gastric ultrasound is a valuable point-of-care tool for assessing gastric contents and volume, particularly in patients with an uncertain fasting status or an increased risk of delayed gastric emptying. However, interpreting preanesthetic gastric ultrasound findings and deciding whether to proceed with surgery require careful clinical judgment and should not be based solely on ultrasound results.

An integrative decision-making algorithm that incorporates preanesthetic gastric ultrasound findings together with the overall clinical context, including surgical urgency and patient-specific risk factors, is presented in Fig. 4. This framework is intended to support individualized risk assessment and management rather than to mandate rigid thresholds for the delay or cancellation of surgery.

Fig. 4.

Integrative decision-making algorithm for proceeding with surgery based on preanesthetic gastric ultrasound findings. An empty stomach or low-volume clear fluid (< 1.5 mL/kg) supports proceeding as planned. The dashed box represents findings categorized as a “full stomach,” including high-volume clear fluid (≥ 1.5 mL/kg), solid contents, and inconclusive examinations. For these high-risk findings, final management should be determined through a shared decision-making process that comprehensively integrates the clinical context. This individualized assessment involves evaluating the anesthetic technique, surgical urgency, the feasibility of modifying or delaying the procedure, and patient preferences. Based on this integrated assessment, clinicians may choose to proceed with modifications (e.g., aspiration mitigation strategies) or reschedule the procedure, including a time delay for a follow-up scan or postponement.

While the presence of solid content or an estimated gastric volume ≥1.5 mL/kg of clear fluid on gastric ultrasound is widely accepted as a practical threshold for defining a “full stomach” [48], a direct relationship between this volume-based definition and clinically significant pulmonary aspiration has not been conclusively established [49,50]. The reported incidence of pulmonary aspiration in clinical practice (approximately 0.031%) [51] is substantially lower than the prevalence of a “full stomach” detected by gastric ultrasound (approximately 6%) [4,48]. Therefore, although a higher estimated gastric volume indicates an increased theoretical aspiration risk, it alone cannot reliably predict the occurrence of aspiration pneumonia. Pulmonary aspiration remains a multifactorial event that is influenced by patient characteristics, anesthetic techniques, airway management, and surgical context.

Additionally, gastric ultrasound examinations may be inconclusive in up to 5% of patients with severe obesity, and the diagnostic performance of gastric ultrasound, including its sensitivity, specificity, and predictive value for identifying a full stomach, has yet to be fully established [15,16,45,52].

Therefore, preoperative gastric ultrasound findings should be integrated into a broader clinical context, including surgical urgency, patient comorbidities, fasting history, and institutional resources. Decisions to delay, postpone, or cancel surgery based on gastric ultrasound findings should be made cautiously and shared decision-making among anesthesiologists, surgical teams, and patients is required.

Importantly, surgical delays may carry their own risks, including disease progression, increased patient anxiety, organizational challenges related to surgical scheduling and resource allocation, and potential harm to urgent or semi-urgent procedures. When surgery proceeds despite gastric ultrasound findings suggestive of a full stomach, alternative strategies to minimize aspiration risk may be considered, such as modification of patient positioning (ramped position), rapid sequence induction (RSI), or use of regional anesthesia when appropriate [53].

This consensus emphasizes that gastric ultrasound should be used to enhance patient safety by refining perioperative risk stratification rather than creating rigid criteria mandating surgical cancellation in the absence of compelling clinical indications.

Management strategies when preoperative gastric ultrasound is not feasible

Despite appropriate training and standardized scanning techniques, preoperative gastric ultrasound may not always be feasible or may yield inconclusive findings in clinical practice [14,17,18,23]. In such situations, anesthetic decision-making should follow a structured, clinically integrated approach to aspiration risk management [14,17,23].

Situations limiting the feasibility of gastric ultrasound

The performance and interpretation of preoperative gastric ultrasound may be limited by patient-, operator-, and system-related factors [14,17,18,23]. Patient-related limitations include severe obesity, marked abdominal distension, advanced pregnancy, significant pain or agitation preventing positional change, and the presence of surgical wounds, drains, or ostomies that interfere with probe placement [14,18,23]. In such circumstances, inadequate visualization of the gastric antrum may lead to unreliable assessment and potential underestimation of the gastric contents [18,23].

Operator- and system-related limitations include insufficient training or experience, time constraints in emergent surgeries, and suboptimal image quality attributable to equipment limitations [14,17,23]. Even when images are obtained, interpretation may remain uncertain owing to ambiguous antral grading or discordance between sonographic findings and the overall clinical context [17]. In such cases, reliance on gastric ultrasound findings alone may be inappropriate [14,17].

Clinical approach in the absence of reliable ultrasound findings

The absence of gastric ultrasound data should not be interpreted as evidence of an empty stomach [17,54]. When preoperative gastric ultrasound is unavailable or yields inconclusive results, aspiration risk assessment should be based on a structured clinical evaluation [17,54–56]. This includes consideration of fasting duration and content, reliability of fasting history, presence of conditions or medications associated with delayed gastric emptying, such as diabetes mellitus, opioid use, or GLP-1 RA use, and the urgency of the surgical procedure [54–56].

When clinical assessment suggests an increased risk of aspiration, appropriate precautionary measures should be implemented regardless of whether gastric ultrasound has been performed [54,56].

Implications for anesthetic management

In situations in which uncertainty regarding gastric contents persists, a conservative approach that mitigates aspiration risk is recommended [43,55,56]. These measures include RSI, securing the airway with a cuffed endotracheal tube, and avoiding deep sedation without definitive airway protection [43]. Surgical delay with reassessment may be considered when clinically acceptable in elective procedures. In urgent or emergent cases, surgery should proceed with a modified anesthetic plan tailored to the aspiration risk [43]. In addition, when aspiration risk is increased or uncertain, clinicians should provide appropriate preoperative communication regarding aspiration risk and the rationale for modified anesthetic management as part of the informed consent process [54].

Perioperative anesthesia management in full-stomach patients

Gastric ultrasound can help clinicians assess aspiration risk and guide anesthetic management. When a gastric ultrasound demonstrates a full stomach, anesthetic management may proceed using full-stomach precautions to minimize the risk of pulmonary aspiration rather than automatically delaying or canceling elective surgery. When gastric ultrasound findings are inconclusive, anesthetic management may proceed with full-stomach precautions. Fatal pulmonary aspiration during anesthesia is extremely rare; however, it remains the most significant cause of airway-related mortality [2]. Accordingly, anesthesiologists should implement appropriate aspiration mitigation strategies when managing at-risk patients (Table 4). Strategies to reduce the risk of aspiration include the administration of preanesthetic medications, nasogastric tube insertion, RSI, regional anesthesia, and a ramped position. However, a clear consensus regarding the thresholds for proceeding with surgery, delaying the procedure, and determining the appropriate level of aspiration precautions remains lacking.

Table 4.

Perioperative Anesthesia Management in Full-Stomach Patients

Strategy	Key points	Recommendation
Preoperative management
Prokinetics	Gastric volume ↓, pH ↑	Consider in high-risk patients; not for routine use
H2 receptor antagonists	Gastric volume ↓, pH ↑	Consider in high-risk patients; not for routine use
Proton pump inhibitors	Gastric volume ↓, pH ↑	Consider in high-risk patients; not for routine use
Antacids (nonparticulate)	Gastric pH ↑	Consider in high-risk patients; not for routine use
Nasogastric tube	Gastric decompression	May reduce aspiration risk
Perioperative management
RSI with cuffed ETT	Airway protection	Recommended
Cricoid pressure	Controversial benefit	Individualized approach
	May hinder intubation

H²: histamine-2, RSI: rapid sequence induction, ETT: endotracheal tube.

Preoperative management

(1) Prokinetics

Two prokinetic agents are relevant in the perioperative setting: metoclopramide and erythromycin [57,58]. Metoclopramide, a dopamine D₂-receptor antagonist, is the most widely studied prokinetic for preoperative use. A pooled analysis of placebo-controlled trials cited in the ASA preoperative fasting guidelines indicated that metoclopramide reduced the perioperative gastric volume and acidity [56], and ultrasonographic studies confirmed a reduction in gastric volume in non-fasted patients [59,60]. Erythromycin, a motilin-receptor agonist, reduces gastric volume independent of its antibiotic activity. A previous study demonstrated that erythromycin, a prokinetic agent, effectively reduced gastric volume in surgical patients [61].

When the two agents were compared directly, they produced comparable reductions in gastric volume across several perioperative populations [62,63]. However, the magnitude of the benefit in perioperative settings appears to depend on the presence of residual gastric content. In appropriately fasted patients undergoing elective procedures, prokinetic administration confers little additional reduction in gastric volume [64,65]. Accordingly, although prokinetic agents may be administered preoperatively to patients at an increased risk of aspiration, routine prophylactic administration to reduce aspiration risk is not recommended.

(2) Histamine-2 receptor antagonists

The ASA preoperative fasting guidelines indicate that histamine-2 (H₂)-receptor antagonists reduce gastric volume and increase gastric pH during the perioperative period, although the evidence is insufficient to confirm a reduction in pulmonary aspiration [56]. Accordingly, the preoperative administration of H2-receptor antagonists may be considered in patients at an increased risk of aspiration, whereas routine prophylactic use in patients without an apparent risk is not recommended.

(3) Proton pump inhibitors

Similarly, the ASA guidelines report that proton pump inhibitors (PPIs) effectively reduce gastric volume and acidity during the perioperative period. For example, a randomized trial found that intravenous pantoprazole significantly increased gastric pH and reduced gastric volume compared with a placebo in patients undergoing elective surgery [66]. However, evidence is insufficient to determine whether PPIs reduce the incidence of pulmonary aspiration. Accordingly, PPIs may be considered in patients at an increased risk of aspiration, but routine administration in low-risk patients is not recommended [56].

(4) Antacids

According to the same guidelines, available studies suggest that preoperative antacid administration increases gastric pH, although their effects on gastric volume have been inconsistent. However, evidence is insufficient to demonstrate a reduction in pulmonary aspiration. Therefore, non-particulate formulations of antacids may be administered to patients at an increased risk of aspiration, but routine administration in low-risk patients is not recommended [56].

(5) Nasogastric tube

In selected high-risk patients such as those with bowel obstruction, ileus, or gastric outlet obstruction, a nasogastric tube can be used to decompress the stomach and remove the gastric contents [67]. This can reduce the intragastric pressure and volume that may lower the risk of aspiration [68]. However, routine nasogastric tube insertion is not recommended.

Perioperative management

(1) RSI using cuffed endotracheal tube with or without cricoid pressure

RSI is traditionally employed in patients at risk of pulmonary aspiration, particularly those who do not comply with preoperative fasting guidelines. Classically, RSI protocols include the mechanical application of cricoid pressure. Despite its longstanding acceptance, robust clinical evidence supporting the efficacy of cricoid pressure in preventing pulmonary aspiration during RSI remains limited. A large, randomized trial did not demonstrate a clear clinical benefit of cricoid pressure, although the rarity of aspiration events limited definitive conclusions, and some studies have reported increased difficulty with laryngoscopy and prolonged intubation times when cricoid pressure was applied [69]. The routine application of cricoid pressure during RSI remains controversial, and its use should be individualized according to the clinical context [40].

(2) Regional anesthesia

General anesthesia can weaken the tone of the lower esophageal sphincter, potentially increasing the risk of aspiration [70,71]. In contrast, regional anesthesia allows the patient to remain awake, preserving the esophageal sphincter tone and protective airway reflexes. Therefore, regional anesthesia in patients with a full stomach may help prevent aspiration [40].

(3) Ramped position

The head-up position has been shown to reduce pulmonary aspiration of gastric contents in mechanically ventilated patients [72]. Similarly, a ramped (head-up) position is theoretically expected to reduce the risk of passive regurgitation of gastric contents, although direct evidence in fasted patients is limited. In addition, it is particularly beneficial in patients with obesity as it extends the safe apnea time by increasing the functional residual capacity [73] and improves the laryngeal view by better aligning the airway axes [74]. However, in a multicenter randomized trial of critically ill adults, the ramped position was associated with a poorer glottic view and a lower first-attempt intubation success rate than the sniffing position [75]. Accordingly, patient positioning should be individualized based on clinical characteristics and airway assessment.

Special consideration for patients receiving GLP-1 RAs or GLP-1/GIP RAs

GLP-1 and GLP-1/GIP RAs are increasingly used for the treatment of type 2 diabetes mellitus and obesity (Table 5). These agents provide important metabolic and cardiovascular benefits, including improved glycemic control, clinically meaningful weight reduction, and potential cardiovascular and renal protection [76]. As their use increases, anesthesiologists are increasingly likely to encounter patients receiving these medications in the perioperative setting. However, GLP-1 RA–based therapies delay gastric emptying, raising concerns about residual gastric contents and potential pulmonary aspiration during anesthesia or deep sedation. Recent observational studies and meta-analyses have consistently shown that the use of GLP-1 RA–based therapies is associated with a higher prevalence of residual gastric contents despite adherence to standard fasting instructions, although a clear increase in pulmonary aspiration events has not yet been demonstrated [12,77].

Table 5.

Summary of FDA Approved Indications of GLP-1 RA–based Therapies [54]

Medication	FDA-approved indications
Semaglutide (Ozempic)	Glycemic control in type 2 diabetes mellitus; reduction of MACE; slowing progression of chronic kidney disease
Semaglutide (Wegovy)	Chronic weight management in adults with obesity or overweight; reduction of MACE; treatment of metabolic dysfunction-associated steatohepatitis with F2–F3 fibrosis
Tirzepatide (Mounjaro)	Glycemic control in type 2 diabetes mellitus
Tirzepatide (Zepbound)	Chronic weight management in adults with obesity or overweight; treatment of moderate-to-severe obstructive sleep apnea in adults with obesity
Dulaglutide (Trulicity)	Glycemic control in type 2 diabetes mellitus; reduction of MACE
Orforglipron (Foundayo)	Chronic weight management in adults with obesity or overweight

FDA: U.S. Food and Drug Administration, GLP: glucagon-like peptide, RA: receptor agonist, MACE: major adverse cardiovascular event.

Continuing GLP-1 RAs and GLP-1/GIP RAs before surgery

Early perioperative recommendations adopted a precautionary approach, suggesting temporary discontinuation of GLP-1 RA–based therapies before elective procedures [78]. However, more recent guidelines have shifted away from universal drug withholding because short-term cessation may not reliably normalize gastric emptying and may compromise glycemic control, particularly in patients with diabetes mellitus [54,58,79–81] (Table 6).

Table 6.

Comparison of Major Guideline Recommendations for Continuing GLP-1 RA–based Therapies

Guideline/Society	Year	Recommendation on Continuation	Conditions for Continuation	Recommendation Level/Evidence Grade	References
ASA — Initial	2023	Hold: Daily dose — hold on day of procedure; weekly dose — hold ≥ 1 wk before	All patients, irrespective of indication, dose, or procedure type	Expert consensus (no formal grading)	[78]
AGA	2024	Individualized approach: Do not routinely hold; proceed if no GI symptoms	Symptom-based risk stratification; hold only if GI symptoms present	Expert opinion (Rapid Clinical Practice Update)	[79]
BJA/Netherlands Expert Commentary	2024	Continue after ≥ 12 wk of stable dosing; caution if recently commenced	Standard fasting likely sufficient after tachyphylaxis (≥ 12 wk); caution during dose escalation	Expert opinion (no formal grading)	[89]
SPAQI	2025	Continue with individualized approach; routine discontinuation not recommended	Confirm not in dose escalation phase, no high-dose, no GI symptoms; preoperative fasting protocol	Modified Delphi consensus + systematic review	[94]
ADS/ANZCA/GESA/NACOS	2025	Continue— explicitly recommend continuation	24-h clear fluid diet + standard 6-h fasting for all patients; gastric ultrasound if liquid diet not completed	Expert panel consensus (multi-society)	[58]
ADA	2026	Personalized approach: allow continuation for low-risk patients	Consider indication, glycemic management, dose/duration, GI symptoms, surgery type/urgency, anesthesia type	Evidence level E (Expert consensus)	[81]
Multi-society guidance	2025	Preoperative GLP-1 RA therapy may be continued in patients without elevated risk of delayed gastric emptying and aspiration	If the decision to hold GLP-1 RAs is indicated given an unacceptable safety profile following shared decision-making in the preoperative period, the duration to hold therapy is unknown	Limited data-based practice guidance	[80]

GLP: glucagon-like peptide, RA: receptor agonist, ASA: American Society of Anesthesiologists, AGA: American Gastroenterological Association, GI: gastrointestinal, BJA: British Journal of Anaesthesia, SPAQI: Society for Perioperative Assessment and Quality Improvement, ADS: Australian Diabetes Society, ANZCA: Australian and New Zealand College of Anaesthetists, GESA: Gastroenterological Society of Australia, NACOS: National Association of Clinical Obesity Services, ADA: American Diabetes Association.

Current evidence increasingly supports the continuation of GLP-1 RA–based therapies in most patients before surgery rather than routine preoperative discontinuation. This approach is based on several key considerations. First, short-term drug interruption does not reliably normalize gastric emptying. The optimal withholding interval remains unknown, but prospective studies have shown that increased residual gastric content may persist for several days after discontinuation [12,82]. Second, discontinuation of these agents may worsen perioperative glycemic control, particularly in patients with diabetes mellitus. As perioperative hyperglycemia is associated with an increased risk of infection, reoperation, and mortality, drug discontinuation may introduce clinically meaningful metabolic harm [81,83–86]. Third, the effect of GLP-1 RA–based therapies on gastric emptying may be attenuated during long-term treatment because of tachyphylaxis, suggesting that aspiration risk may not be uniform across all patients [87–89]. Fourth, although the use of GLP-1 RA–based therapies is consistently associated with increased residual gastric content, the available studies have not demonstrated a clear increase in actual pulmonary aspiration events [90–92].

Therefore, routine discontinuation is not recommended for all patients, and continuation may be appropriate in most clinically stable patients after individualized risk assessment, considering gastrointestinal symptoms (nausea, vomiting, dyspepsia, and abdominal distension), recent dose escalation, high-dose or long-acting formulations, obesity, diabetes, and the duration of therapy.

24-h clear liquid diet protocol

A 24-h clear liquid diet may be considered a perioperative risk-mitigation strategy in patients receiving GLP-1 RA–based therapies before anesthesia or deep sedation [81]. This dietary strategy may reduce residual gastric content without requiring routine medication discontinuation.

A 24-h clear liquid diet protocol may provide a practical risk-mitigation strategy for patients receiving GLP-1 RA–based therapies before anesthesia or deep sedation. This rationale is based on the following three considerations. First, GLP-1 RA–based therapies appear to delay gastric emptying, predominantly for solid content rather than for liquids. In a meta-analysis, scintigraphy-based solid gastric emptying was delayed, whereas acetaminophen absorption testing that mainly reflects liquid emptying, did not show a significant delay in time to maximum concentration or a significant difference in the area-under-the-curve analysis [93]. This supports the physiological concept that avoiding solid food for 24 h may reduce the likelihood of retained solid gastric contents while allowing liquid intake according to standard fasting principles [87,93].

Second, the clinical evidence supports the effectiveness of this dietary strategy. In the OCULUS randomized trial, a clinically significant residual gastric volume was not observed in the esophagogastroduodenoscopy-plus-colonoscopy subgroup that received a clear liquid diet, regardless of whether GLP-1 RA–based therapies were continued or withheld [92].

Third, this strategy may reduce gastric content risk without routine medication discontinuation. Since the optimal withholding interval for GLP-1 RA–based therapies remains uncertain and short-term discontinuation may not reliably normalize gastric emptying, a 24-h clear liquid diet offers a clinically feasible alternative that preserves glycemic control while reducing the risk of retained gastric contents [81,82,92] (Table 7).

Table 7.

Comparison of Major Guideline Recommendations for a 24-h Liquid Diet

Guideline	Recommendation for a 24-h liquid dieta	Target population	Recommendation Level/Evidence Grade	References
ADA (2026)	May be helpful	Mainly high-risk patients	Evidence level E (Expert consensus)	[81]
ADS/ANZCA/GESA/NACOS (2025)	Should be recommended	All patients receiving	Expert panel consensus (multi-society); no formal grading system used	[58]
	Preprocedural diet modification with 24-h clear fluid diet, followed by standard 6-h fasting	GLP-1 RA/GIP RA
SPAQI (2025)	Included in the fasting for solids for 24 h (only clear liquids allowed)	Individualized approach	Modified Delphi consensus + systematic review	[94]
Mayo Clinic Proceedings (2025)	May benefit high-risk patients	High-risk patients	Narrative review (expert opinion)	[95]
BJA Editorial (2026)	Recommended for high-risk patients	High-risk patients	Expert editorial commentary	[96]

^a24-h clear liquid diet protocol components: (i) Diet: Patients should consume clear liquids only, beginning 24 h before anesthesia/sedation; (ii) Subsequent fasting: Standard preanesthetic fasting, under which clear liquids are permitted for up to 2 h before anesthesia/sedation; (iii) Purpose: To reduce residual gastric contents associated with delayed gastric emptying, thereby mitigating the risk of pulmonary aspiration; (iv) Clear liquids: water, fruit juice without pulp, tea, coffee without milk or cream, clear broth, and sports drinks [3]. ADA: American Diabetes Association, ADS: Australian Diabetes Society, ANZCA: Australian and New Zealand College of Anaesthetists, GESA: Gastroenterological Society of Australia, NACOS: National Association of Clinical Obesity Services, GLP: glucagon-like peptide, RA: receptor agonist, GIP: glucose-dependent insulinotropic polypeptide, SPAQI: Society for Perioperative Assessment and Quality Improvement, BJA: British Journal of Anaesthesia.

Therefore, a 24-h clear liquid diet followed by standard fasting may be recommended as part of an individualized perioperative strategy, particularly when medication continuation is preferred and aspiration risk requires additional mitigation.

Preoperative gastric ultrasound in patients receiving GLP-1 RA–based therapies

Preoperative gastric ultrasound is not routinely recommended for all patients receiving GLP-1 RA–based therapy. Instead, it should be considered as a selective point-of-care tool to objectively assess gastric contents and individualize anesthetic management when aspiration risk remains uncertain (Table 8).

Table 8.

Comparison of Major Guideline Recommendations on Gastric Ultrasound

Guideline	Recommendation on Gastric Ultrasound	Target Population	Level of Recommendation	References
ADA (2026)	May be considered to quantify gastric contents	As part of an individualized approach when aspiration risk is uncertain	Expert consensus (E)	[81]
ADS/ANZCA/GESA/NACOS (2025)	Risk stratification using	Patients who have not completed a 24-h clear liquid diet	Expert consensus	[58]
	Gastric Ultrasound is recommended
AGA (2024)	Transabdominal ultrasonography can be used	Symptomatic patients, when expertise and equipment are available	Expert opinion	[79]
SPAQI (2025)	Recommended as an adjunct to the preoperative fasting protocol	High-risk patients who do not follow dietary restrictions and in patients who describe gastrointestinal symptoms	Modified Delphi consensus	[94]
ASRA (2026)	Should be considered when clinical uncertainty exists	Patients with uncertain aspiration risk, particularly when the pretest probability of a full stomach is approximately 50%	Expert recommendation	[29]
Multi-society guidance (2025)	Could be used to assess aspiration risk	Clinical concern for retained gastric contents exists	Practice guidance	[80]

ADA: American Diabetes Association, ADS: Australian Diabetes Society, ANZCA: Australian and New Zealand College of Anaesthetists, GESA: Gastroenterological Society of Australia, NACOS: National Association of Clinical Obesity Services, AGA: American Gastroenterological Association, SPAQI: Society for Perioperative Assessment and Quality Improvement, ASRA: American Society of Regional Anesthesia and Pain Medicine.

Gastric ultrasound may be considered in the following clinical situations: (1) when a 24-h clear liquid diet has not been completed or cannot be implemented [5,9,10]; (2) when symptoms suggestive of delayed gastric emptying are present, including nausea, vomiting, dyspepsia, early satiety, or abdominal distension [79,81,94]; (3) when aspiration risk remains uncertain after individualized clinical assessment [81,94]; and (4) when additional risk factors are present, such as recent dose escalation, obesity, diabetes mellitus, opioid use, or known or suspected gastroparesis [12,81,82,87,92,94–96].

Gastric ultrasound findings should be integrated into the overall clinical context to guide anesthetic management, including proceeding with standard induction, performing rapid sequence induction and tracheal intubation, and postponing the procedure when a full stomach is identified.

Conclusions

Preanesthetic gastric ultrasound provides a practical bedside method for assessing gastric contents and estimating aspiration risk in patients undergoing anesthesia. In contemporary perioperative practice, where the fasting status may be uncertain, gastric emptying may be delayed, and medications affecting gastric motility may be used, individualized risk assessment has become increasingly important. Gastric ultrasound serves as a real-time adjunct to traditional fasting guidelines and clinical evaluations.

This consensus statement provides expert-informed recommendations covering the indications, examination techniques, interpretation, perioperative decision-making, and special considerations for patients receiving GLP-1 RA–based therapies, offering a practical framework for preanesthetic gastric ultrasound in clinical practice.

Further prospective studies evaluating patient-centered outcomes, standardization of training and competency assessment, and validation of risk-stratified management algorithms are needed, particularly regarding the optimal perioperative management of patients receiving GLP-1 RA–based therapies, to strengthen the evidence base and refine future recommendations.

Supplementary Materials

Supplementary Table 1.

Final consensus results for each recommendation following the modified Delphi process.

Supplementary Video 1.

Gastric ultrasound (English).

Supplementary Video 2.

Gastric ultrasound (Korean).