Increased incidence of gastric food retention during endoscopic retrograde cholangiopancreatography in liver transplant recipients: A retrospective cohort study

Abstract

BACKGROUND

Gastric food retention during endoscopic retrograde cholangiopancreatography (ERCP) can lead to complications such as aspiration and failed procedure. Liver transplant (LT) recipients are exposed to an increased risk of impaired gastrointestinal motility due to surgical alterations, immunosuppressive therapy, and post-transplant complications. Given the high frequency of ERCP in this population, our anecdotal experience suggests an increased incidence of gastric food retention at the time of the procedure.

AIM

To evaluate the association between LT and gastric food retention observed at ERCP over a two-year period.

METHODS

This retrospective study included all patients who underwent standard ERCP at our institution between 2022 and 2024. Data were collected on demographics, medical history including LT and procedural details.

RESULTS

A total of 1100 patients underwent ERCP, including 238 LT recipients (22%). Gastric food retention was observed 17 patients (1.5%). The incidence was significantly higher in LT recipients compared to non-transplant patients (3.8% vs 0.9%, P = 0.004). Multivariate analysis confirmed that LT recipients were independently associated with an increased risk of food retention.

CONCLUSION

LT recipients demonstrated over three-fold increased incidence of gastric food retention during ERCP. This should be considered in pre-procedural assessment and preparation in this patient population.

Key Words: Liver transplantation; Endoscopic retrograde cholangiopancreatography; Gastroparesis; Gastric stasis; Gastric food retention; Endoscopy

Core Tip: To our knowledge, no previous studies have specifically investigated the real-world incidence of gastric food retention during endoscopic retrograde cholangiopancreatography in liver transplant (LT) recipients compared to non-LT patients. This study identified a more than three-fold increase in the incidence of gastric food retention among LT recipients. Given the potential risks associated with procedures performed under sedation or general anaesthesia, this study highlights the need for the heightened awareness to minimise the risk of airway compromise, procedural complications, and the burdens of repeated procedures in this patient cohort.

INTRODUCTION

Endoscopic retrograde cholangiopancreatography (ERCP) is widely used as a first-line treatment for biliary complications, which occur in 6%-34% of liver transplant (LT) recipients[1]. ERCP is effective in managing biliary strictures, the most common indication for ERCP in this population[2]. While ERCP has a comparable safety profile between LT recipients and non-transplant patients[2], multiple factors can influence procedural success and safety, including pre-operative preparation, anatomical variations, and the presence of gastric content intraoperatively[3].

Gastric food retention is a critical yet often overlooked factor that may increase procedural risk. The presence of gastric contents can obscure endoscopic vision, increase the aspiration risk, and prolong procedural time, potentially delaying definitive treatment. Current literature suggests that recipients of solid organ transplants may exhibit higher rates of gastric food retention at endoscopy, with reported incidences of 19%[4], compared to 4.5% in non-transplant patients[5]. However, the study by Jarret et al[4] included patients with suspected gastroparesis and therefore may have led to an overestimation in this cohort. The estimated rate of gastroparesis in the general population is 1.8%[6], but the incidence among post-transplant recipients remains unknown.

Several conditions can cause impaired gastrointestinal motility such as diabetes[7], altered anatomy after gastric surgery[8], and end-stage liver disease[9], all of which may contribute to an increased risk of gastric food retention. A recent study by Jia et al[3] identified gender, jaundice, opioid use, and gastrointestinal obstruction as independent risk factors for gastric food retention during ERCP. Despite ERCP being required in up to 30% of LT recipients for the management of biliary complications[10], no studies have specifically explored the association between LT and impaired gastric motility or its impact on procedural safety.

The study aims to investigate the relationship between LT and gastric food retention during ERCP by comparing LT recipients with non-transplant patients. It seeks to identify the prevalence of food retention in both groups, explore potential contributing factors, and assess the clinical implications for procedural planning and patient safety.

MATERIALS AND METHODS

This retrospective cohort study included consecutive patients who underwent ERCP between January 2022 and March 2024 at Austin Health, a tertiary referral hospital and LT center in Melbourne, Australia. A standard pre-procedural fasting protocol was applied, with all patients fasted from solid foods for six hours and from liquids for two hours before the procedure. ERCP was performed under monitored anaesthesia care without intubation as the standard practice; however, general anaesthesia was administered when clinically indicated[11]. Patient demographic, clinical history, and procedural details were collected from the hospital’s electronic medical record system. Demographic data included age and gender, while clinical data comprised comorbid conditions such as diabetes mellitus, prior gastric surgery, and LT status. Procedural details collected were indications for ERCP and presence of gastric food retention. Gastric food retention was defined as the visible presence of undigested gastric contents in the stomach or duodenum during duodenoscope passage. The primary objective was to assess the association between LT and gastric food retention during ERCP, and the secondary objective was to evaluate the potential contributing factors.

Ethical considerations

This study received ethical approval from the Health Human Research Ethics Committee of Victoria Translational Research Institute (HREC/107308/Austin-2024) and was conducted in accordance with the Declaration of Helsinki. As this was a retrospective study using anonymised clinical data, individual informed consent was waived, with appropriate privacy protections in place.

Statistical analysis

Continuous variables were summarised as mean ± SD, and categorical variables were presented as frequencies and percentages. Associations between categorical variables were analysed by χ² test or Fisher’s exact test when appropriate. A multivariable logistic regression analysis was employed to identify independent predictors of gastric food retention, incorporating variables with P < 0.1 in univariate analysis. Statistical significance was set at P < 0.05. Statistical analysis was conducted using SPSS Statistics, Version 27.0 (IBM Corp., Armonk, NY, United States).

RESULTS

A total of 1,100 ERCP procedures were included in the analysis, with a mean age of 62 years (SD = 16.5) (Table 1). LT recipients comprised 22% of the cohort. Gastric food retention was observed in 1.5% (n = 17) of all patients. Compared to non-transplant patients, LT recipients were significantly younger (57 vs 64 years, P < 0.01) and had a higher prevalence of diabetes mellitus (40% vs 15%, P < 0.001). The incidence of gastric food retention was significantly higher among LT recipients than non-transplant patients (3.8% vs 0.9%, P = 0.004). Multivariate logistic regression analysis identified LT as an independent risk factor for gastric food retention [odds ratio (OR) = 3.53; 95%CI: 1.28-9.67; P = 0.02], after multivariable adjustment for age and diabetes mellitus (Table 2).

Table 1 Overview and demographic characteristics of patients who underwent endoscopic retrograde cholangiopancreatography, n (%)/mean ± SD.

Patient characteristics (n = 1100)
Age (years)	62.3 ± 16.5
Female	522 (47.5)
Liver transplant	238 (21.6)
Diabetes	227 (20.6)
Previous Gastric Surgery	8 (0.7)

Table 2 Factors associated with gastric food retention in endoscopic retrograde cholangiopancreatography patients: Univariate and multivariate analyses, n (%)/mean ± SD.

Variable	Food retention	No food retention	Univariate analysis (P value)	Multivariate analysis
				Adjusted OR	95%CI	P value
Age (years)	57 ± 19.5	62 ± 16.4	0.17	0.98	0.75-6.93	0.16
Sex (male)	8 (1.4)	570 (98.6)	0.8	-	-	-
LT recipient	9 (3.8)	229 (96.2)	0.04	3.5	1.28-9.68	0.035
Diabetes mellitus	7 (3.0)	220 (97.0)	0.06	1.9	0.95-1.01	0.22
Gastric surgery	0 (0)	8 (100)	1.0	-	-	-

LT: Liver transplant; OR: Odds ratio.

DISCUSSION

This retrospective cohort study evaluated contributing factors to gastric food retention during ERCP. Our findings demonstrate an over three-fold increased risk of food retention in LT recipients, suggesting that the current standard pre-procedural fasting protocols may be inadequate for this immunocompromised population. The increased incidence of gastric retention among LT recipients can be attributed to a combination of pre and post-transplant factors. Patients undergoing LT often have underlying liver cirrhosis or hepatic malignancy. Gastric motility is regulated by the autonomic nervous system coordination, particularly the vagus nerve, which plays a critical role in both the motor and sensory pathways that control gastric contractions and propulsion[12]. A systematic review reported that impaired gastric motility is prevalent in up to 75% of patients with advanced liver disease[9], largely due to autonomic dysfunction characterized by heightened sympathetic activity and downregulated parasympathetic tone[9]. The autonomic impairment can persist after LT, though the degree and the timing of its reversibility are uncertain. Hepatic malignancy, a common indication for LT[13], has also been associated with a higher incidence of gastroparesis, potentially due to multifactorial mechanisms[14]. Although the exact pathophysiology of post-LT gastroparesis is underexplored, one hypothesis is that surgical interventions can result in injury to the hepatic branch of the vagus nerve during LT may contribute to delayed gastric emptying, a phenomenon observed after hepatectomy[15]. Immunosuppressive therapy may also play a role in impaired gastric motility. Common agents include calcineurin inhibitors, corticosteroids, molecular target of rapamycin inhibitors, and antimetabolites[16]. Although animal studies suggest that most of these agents impair gastrointestinal motility[16], similar studies in humans are limited. Furthermore, immunosuppressive therapy has been shown to alter gut microbiota and increase susceptibility to gastrointestinal infections, which may further exacerbate gastric motility issues[17]. Notably, solid organ transplantation is a significant factor in gastric motility impairment with one study showing a rate of 19% retained food contents in solid organ transplant recipients[4].

Given the frequent need for ERCP in post-LT care to reduce morbidity, mortality and preserve graft function in those who develop biliary complications[18], addressing gastric food retention is essential. Gastric food retention at ERCP can compromise procedural success and may lead to aborted procedures, increasing healthcare burden through prolonged hospital stays, resource utilisation, and costs. This is particularly concerning in LT recipients, who are already vulnerable to complications such as prolonged anaesthesia and post-procedural infections due to immunosuppression[19].

In our cohort, age, gender, diabetes, and prior gastric surgery were not significantly associated with gastric food retention. The higher rate of food retention in LT patients (3.8% vs 0.9%) aligns with existing literature on delayed gastric emptying in patients with solid organ transplants, albeit lower than the reported 19%. This discrepancy is likely due to differences in study populations, as prior studies primarily examined symptomatic patients undergoing endoscopic evaluation for suspected gastroparesis[4]. While previous reports have shown that female sex, older age (> 60 years), diabetes, and prior gastric surgery are risk factors for gastroparesis[3,8,20], our findings suggest that standard fasting may remain adequate for these populations.

The American Society of Anaesthesiologists recommends a standard fasting protocol of six hours for solid foods and two hours for liquids prior to procedures[21]. However, our findings suggest that this may not be adequate for LT recipients. Fasting protocols could include a prolonged solid fast, the use of prokinetics, or pre-procedural liquid may be beneficial, although evidence regarding the required duration of liquid fasting remains limited[22].

We propose a modified fasting protocol for LT recipients to reduce the risk of gastric retention: (1) A liquid diet for 24 hours before the procedure; (2) Nil by mouth for 12 hours prior to procedure; (3) Administration of a prokinetic agent (e.g., metoclopramide 10 mg three times daily) for three days pre-procedure; or (4) Intravenous erythromycin 250 mg administered 60 minutes before the procedure.

This study has several limitations that should be acknowledged. First, the assessment of gastric food retention was based on subjective visual inspection during ERCP, which introduces potential observer variability. Pre-procedural gastric ultrasound may offer a more objective and standardised assessment[21], although its routine use may be limited by availability and logistical constraints. Second, the small number of retention events (n = 17) reduced statistical power and may have limited our ability to detect significant associations. Although the observed odds rate of 3.5 is clinically significant, the wide confidence interval indicates variability and limits certainty. As a single-center retrospective study, generalisability is limited due to potential differences in patient populations or procedural protocols. In addition, we did not assess gastric emptying via standardised motility tests (i.e. scintigraphy), making it difficult to directly attribute gastric retention to delayed gastric emptying. While diabetes was accounted for, other confounding factors, such as opioid use[23], immunosuppressive therapy, prior use of prokinetics, and surgical variations were not extensively analysed. Future research should focus on larger, multicenter studies to validate our findings, refine predictive models, and examine confounding factors more comprehensively. Investigating the pathophysiology of post-LT gastroparesis, including the effects of immunosuppressants, opioids, and vagal nerve injury, as well as the long-term impact of gastric retention on post-transplant outcomes and ERCP efficacy, is essential for gaining valuable clinical insights.

CONCLUSION

This study highlights an increased risk of gastric retention during ERCP in LT recipients, likely due to unique physiological and pharmacological factors. Recognizing and addressing these risks through tailored preoperative preparations and interventions is crucial for improving procedural success and patient outcomes. Given the high frequency of ERCP in post-transplant care, optimizing strategies to minimize gastric retention may significantly reduce procedural complications, healthcare costs, and patient burden.