Preoperative gastric retention in endoscopic retrograde cholangiopancreatography

Abstract

We comment on the article by Jia et al, in the World Journal of Gastrointestinal Surgery. We focus mainly on the factors that impair gastric motility and cause gastric retention in the pre-operative setting of endoscopic retrograde cholangiopancreatography (ERCP). ERCP is a complex endoscopic therapeutic procedure, which demands great skill from the endoscopist but also has recognized complications. Gastric retention impairs the endoscopist’s visibility but also increases the risk of complications, such as aspiration pneumonia. Therefore, identifying the factors that predispose to gastric retention alerts the endoscopists of the possible risks and enables them to take evasive action. The authors in the current study by Jia et al developed and validated a predictive model, which incorporates five different factors, i.e., gender, primary disease, jaundice, opioid use, and gastrointestinal obstruction, which were found to influence gastric retention. This model was shown to have a high predictive value to accurately identify patients at risk for gastric retention before a therapeutic ERCP.

Key Words: Gastric retention; Endoscopic retrograde cholangiopancreatography; Predictive model; Malignant gastroparesis

Core Tip: Gastric retention is a relatively common problem prior to endoscopic retrograde cholangiopancreatography (ERCP). In this article, we analyze the factors implicated in gastric retention in ERCP patients, before to their procedure. We also comment on a new predictive model, which can accurately identify patients at greatest risk for gastric retention, thereby helping physicians to avoid complications, unnecessary delays and increased hospital costs.

TO THE EDITOR

Endoscopic retrograde cholangiopancreatography (ERCP) is a complex endoscopic procedure, which is indicated in patents with choledocholithiasis, biliary or pancreatic tumors, chronic pancreatitis, benign biliary strictures, and lesions of the ampulla of Vater. It involves cannulation of the common bile duct (CBD) or in selected cases, the pancreatic duct (PD), with subsequent endoscopic intervention, according to the indication. This might be a sphincterotomy, stone clearance from the CBD, stent insertion to CBD or PD or indeed ampullectomy[1]. Gastric retention refers to the presence of food residue within the stomach due to delayed gastric emptying. It obscures the endoscopic view and consequently might prolong the procedure and thus, increase the potential for complications. Aspiration pneumonia, a recognized complication of gastric retention, can be life-threatening[2]. In their article, Jia et al[3] developed and validated a new prognostic tool, which accurately identifies patients at risk for gastric retention before their procedure.

ERCP AND GASTRIC RETENTION IN THE PRE-OPERATIVE SETTING

Gastric retention is a concern in the context of any upper gastrointestinal endoscopy, and particularly in the case of ERCP. As a complex therapeutic endoscopic procedure, ERCP usually lasts much longer than a diagnostic endoscopy. It requires a clear view of the duodenum and the papilla of Vater in addition to good patient cooperation. Should gastric retention be present, it can obscure the endoscopist’s view, making the procedure more challenging and in some cases impossible. As a result, post-ERCP pancreatitis or aspiration pneumonia are more frequent complications, leading to longer hospital stays, increased morbidity and mortality combined with greater need for medical resources[4]. ERCP is usually performed under deep or conscious sedation in most centers, which means that the patient is not intubated during the procedure. In this setting, if gastric retention is present, the risk of aspiration pneumonia is high. Endoscopists may have to abandon the procedure and re-schedule it after emptying the stomach with a nasogastric tube[5]. This results in delays in the treatment of patients, increased associated costs and a greater burden on the healthcare system. Therefore, the identification of patients with gastric retention before ERCP is of paramount importance, as it will ensure the safety and efficacy of the procedure.

FACTORS THAT CAUSE GASTRIC RETENTION IN ERCP PATIENTS

In their article, Jia et al[3] studied patients with gastric retention before ERCP and analyzed the factors that contribute to delayed gastric emptying. In their retrospective study, they found that gender, primary disease, jaundice, opioid use, and gastrointestinal obstruction were the key factors that influenced preoperative gastric retention in ERCP patients. Based on these factors, they developed and validated a predictive model (PM) that showed a high predictive value. Gastric retention was more frequent in females compared to males. This finding is not surprising, since females suffer more frequently from anxiety and depression, which have been found to alter gastrointestinal motility and cause delayed gastric emptying[6,7]. Moreover, sex hormones, such as estrogens and progesterone have been shown to affect the physiological process of gastric emptying in different animal studies. In particular, estrogens and progesterone at high doses inhibit gastric motility, while progesterone enhances gastric emptying when administered in low doses[8,9].

Biliary or pancreatic tumors may compress adjacent structures, such as the stomach or the duodenum, thereby causing delayed gastric emptying and significant gastric retention. This can also be caused by growth and direct infiltration of the tumor into the gastrointestinal tract, leading to stenosis or complete gastric outlet obstruction. Inflammation of the adjacent mucosa caused by compression of the stomach or duodenum from a tumor can also impair gastric motility and contribute to delayed gastric emptying.

In the setting of malignancy, gastric retention can also occur without actual compression or infiltration of the stomach by the tumor. It may be caused by gastroparesis, referred to as malignant gastroparesis (MG), which may result from the cancer itself or may be a complication of treatment modalities such as surgery, radiation therapy, or chemotherapy. Coexisting conditions, including diabetes, hypothyroidism, and neurologic diseases, may further exacerbate MG. The pathogenesis of MG remains poorly understood. However, potential mechanisms proposed in the literature include post vagotomy syndrome, malignant infiltration of the autonomic nervous system, and paraneoplastic dysmotility with autoantibody-mediated destruction of the enteric nervous system (the interstitial cells of Cajal, also called the intrinsic pacemaker of the gastrointestinal tract, or the myenteric plexus[10].

Jaundice was another factor that negatively influenced gastric emptying. This probably reflects the existence of a biliopancreatic tumor, which simultaneously obstructs the CBD or the hepatic ducts and the gastrointestinal tract.

Opioids are routinely used in patients with biliopancreatic tumors or choledocholithiasis for pain relief due to their potent analgesic effect. However, these drugs also inhibit gastrointestinal motility and may cause nausea, vomiting and constipation, leading to gastric retention in patients scheduled for ERCP[11].

Gastric obstruction can definitely be caused by a biliopancreatic tumor as mentioned before.

PM

In recent years, there has been growing interest in the development of PMs to enhance the effectiveness and safety of different diagnostic and therapeutic procedures. These models aim to provide clinicians with valuable insight and guidance in decision-making, to optimize patient outcomes, and to reduce potential complications. With respect to ERCP, PMs have been employed so far to predict the likelihood of choledocholithiasis, the likelihood of successful bile duct cannulation during ERCP, the risk of post-procedure complications (such as pancreatitis), the presence of malignancies or mortality risk post-ERCP in patients with malignant biliary strictures[12]. Jia et al[3] successfully developed and validated a new PM, which has a high predictive value and accurately identifies patients at risk for gastric retention before a therapeutic ERCP.

This model incorporates five different factors, namely gender, primary disease, jaundice, opioid use, and gastrointestinal obstruction that were found to influence gastric retention in their univariate and multivariate logistic regression analyses. In their study, Jia et al[3] applied first the new model in the training set of patients: Statistical analysis showed that the model had a high predictive ability in identifying preoperative gastric retention in ERCP patients. When the model was applied in the validation set of patients, it showed an impressive predictive performance, with an area under receiver operating characteristic curve of 0.842, a standard error of 0.013, and a 95% confidence interval of 0.8061-0.9216. When the optimal cutoff value was set to 0.56, the sensitivity was slightly lower at 56.2%, but the specificity was as high as 100.0%, further demonstrating the value of the model. Therefore, this PM was proven to have a high predictive value to accurately identify patients at risk for gastric retention before a therapeutic ERCP. If this model is employed in clinical practice by physicians, it will increase the effectiveness and the safety of the procedure: Patients with gastric retention will be readily identified before ERCP and the procedure can be scheduled after prompt clearance of the gastric residue. Should this not be possible, ERCP could be arranged under general anesthesia, thereby avoiding potential complications. In this way, utilization of medical resources will be more efficient, by reducing potential complications, delays and hospital costs.

The study by Jia et al[3] has some limitations. It is a retrospective study and therefore it does not evaluate the new PM prospectively. It will be interesting to see future studies prospectively evaluating the new PM by comparing the outcome of ERCP patients where the PM is employed with the outcome of those where the PM is not utilized. Outcomes would include parameters like post ERCP complications, duration of hospital stay and healthcare costs. Moreover, future studies should also include larger patient numbers than the present study, thereby providing more robust evidence and strengthening the applicability of this new PM.

CONCLUSION

Gender, primary disease, jaundice, opioid use, and gastrointestinal obstruction are factors that influence preoperative gastric retention in ERCP patients. A new PM was established based on these factors, which was proven to have a high predictive value. Physicians who practice ERCP should be aware of these factors, and this recently established PM, in order to easily identify patients at risk for gastric retention. In this way, complications, unnecessary delays and extra hospital costs can be avoided.