A bezoar is a conglomeration of indigestible materials within the gastrointestinal tract, resulting from the accidental ingestion of various substances. The incidence of gastric bezoars reported in endoscopic examinations ranges from 0.43%–0.68% [1,2]. Although bezoars can be found in any part of the gastrointestinal tract, the stomach is the most commonly affected site. Most gastric bezoars are dissolved and discharged without treatment. However, they can occasionally cause gastric ulceration and bleeding [3], and can also migrate to the small intestine and cause mechanical obstructions. Bezoars represent a rare cause of small bowel obstruction; among patients surgically treated for mechanical small bowel obstruction, 0.8% of cases were associated with bezoars [4]. Therefore, removal of gastric bezoars should be considered in cases of large bezoars (>3 cm) or in symptomatic patients [5,6].

Although the majority of gastric bezoars comprise plant materials, such as fibers, skins, or seeds of vegetables and fruits (phytobezoars), ingested hair (trichobezoar), medications (pharmacobezoar formation due to bulk-forming laxatives, extended-release tablets, or enteric-coating drugs), and other ingested foreign bodies may also result in gastric bezoars [3,7]. The primary predisposing factor for gastric bezoars is delayed gastric emptying. Gastric dysmotility and reduced acid secretion may induce gastric bezoar formation. Conditions associated with gastric dysmotility or decreased gastric acid secretion include previous gastric resection, vagotomy, peptic ulcer disease, advanced age, Crohn disease, and diabetic neuropathy [8,9]. Moreover, there have been reports indicating that certain ingested materials are more prone to cause bezoars [10-13].

Unfortunately, a standardized method for treating gastric phytobezoars has not been adopted. Surgical removal should be attempted in cases with complications such as massive gastrointestinal bleeding or gastrointestinal obstruction. However, outside of emergency situations, chemical lysis using carbonated beverages, proteolytic enzymes, and cellulases has been employed, either alone or in conjunction with endoscopic bezoar removal [3,14-16]. In this study, we reviewed the clinical outcomes and safety of various gastric phytobezoar treatment methods, particularly the consumption of carbonated beverages prior to therapeutic endoscopy.

Gastric bezoars are rarely encountered clinically, but when encountered, phytobezoars are the most common. Phytobezoars are formed from indigestible food materials, such as celery, pumpkins, grape skins, prunes, raisins, and persimmons. In particular, persimmon phytobezoars are challenging to treat due to their hardness compared with other types of phytobezoars [19].

Gastric phytobezoars may be encountered incidentally during routine endoscopies or as a result of an endoscopic examination of a symptomatic patients. However, the optimal treatment approach remains uncertain due to a lack of a consensus regarding the most effective treatment method. For small gastric bezoars, a conservative observational approach may be appropriate because spontaneous passage or dissolution may occur. However, additional treatment modalities may be necessary for gastric bezoars that present symptomatically or are associated with peptic ulceration. In the present study, gastric and duodenal ulcerations were identified in 53.3% (8/15) and 26.7% (4/15) of the cases, respectively. A total of 93.3% of patients exhibited symptoms, including bloating, epigastric pain, and nausea.

To date, the following treatment methods have been identified for phytobezoars. Chemical dissolution, using carbonated beverages or enzymes such as papain and cellulase, is a common treatment method for phytobezoars. In recent years, several studies have been conducted on the use of carbonated beverages for the dissolution of gastric phytobezoars [3,16,20]. In the present study, we used Coca-Cola as the therapeutic carbonated beverage. Here, 46.7% of the patients with gastric phytobezoars experienced spontaneous resolution after drinking the carbonated beverage over a 24–48-hour period. More than half of the patients with gastric bezoars that persisted after the consumption of the carbonated beverage (n=8) were successfully treated with additional endoscopic procedures (n=5). Including patients treated with the carbonated beverage alone (n=7, 46.7%) and with an additional endoscopic therapy (n=5, 33.3%), 80% of the patients (n=12) were successfully treated.

Previous studies have demonstrated that the resolution rate of phytobezoars using carbonated beverages, with or without endoscopic maneuvers, was 84.0%–91.3% [14]. However, during treatment with carbonated beverages that dissolve phytobezoars, migration of small or fragmented bezoars may cause small bowel obstruction. In the present study, small bowel obstructions occurred in 20.0% (n=3) of the patients who consumed carbonated beverages. The use of carbonated beverages as a treatment for phytobezoars was first introduced in 2002 by Ladas et al. [14,21] Following the publication of the initial study report, numerous subsequent studies have demonstrated the efficacy of carbonated beverages for the treatment of gastric phytobezoars [3,16,20]. In addition to carbonated beverages, chemical dissolution agents, such as papain and cellulase, can also be used. Papain, a proteolytic enzyme extracted from Carica papaya, hydrolyzes a wide variety of proteins. A recent study showed that papain was effective in the treatment of proteinaceous esophageal food impaction without complications [22]. However, esophageal perforation, aspiration pneumonitis, and hemorrhagic pulmonary edema have been reported as potential complications associated with the use of proteolytic enzymes [23]. Although the exact mechanism is unknown, these complications are suspected to arise due to the non-target action of such proteolytic enzymes [24,25]. Another useful enzyme is cellulase, which degrades the cellulose that is abundant in vegetables and fruits; therefore, it may be useful for phytobezoar treatment [15]. Additionally, there are also reports of the use of acetylcysteine to treat bezoars, although the literature on it is limited [26-28].

Although the exact mechanism of action of carbonated beverages is not fully understood, the actions of its ingredients are likely contributory: sodium bicarbonate is mucolytic, carbonic and phosphoric acids have an acidifying effect, and carbon dioxide bubbles penetrate the bezoar through microscopic pores [14,19]. A recent in vitro study reported on the dissolution of phytobezoars by chemical dissolution agents. The study showed that chemical dissolution agents (Coca-Cola, papain, and cellulase) were more effective at dissolving phytobezoars than the control (water). Further, Coca-Cola was more effective than papain and cellulase [25]. If a phytobezoar is resistant to the aforementioned chemical dissolution methods, endoscopic fragmentation and removal may be considered. Despite the favorable factors associated with the use of carbonated beverage dissolution (ease, cost, and effectiveness), clinicians should be aware of the possibility of small bowel obstruction due to the migration of fragments of or the whole gastric bezoars, which can occur up to six weeks after migration from the stomach [14]. Consequently, patients should be meticulously monitored for symptoms indicative of small bowel obstruction, such as vomiting and abdominal discomfort, throughout the follow-up period. In cases where such symptoms manifest, CT should be performed.

In the present study, small bowel obstruction occurred in 20.0% (n=3) of the patients following carbonated beverage therapy. Various methods can be employed for endoscopic fragmentation, including the use of endoscopic forceps, polypectomy snares, water jets, neodymium:yttrium-aluminum-garnet lasers, extracorporeal shockwave lithotripsy, and endoscopically guided electrohydraulic lithotripsy. Endoscopic treatment of bezoars is essentially a mechanical crushing process that can be achieved using a variety of instruments available at the institution, including forceps, lithotripters, snares, and argon plasma coagulation [29-32]. Because of the risk of migration, bezoar fragments should be removed during the endoscopic procedure, if possible.

A well-known gastric phytobezoar that is refractory to the aforementioned treatment modalities is the persimmon bezoar. The skin of unripened persimmons contains a high concentration of tannins that react with gastric acid, and then polymerize to form a conglomeration in which cellulose, hemicellulose, and various proteins accumulate [33]. In this study, only one patient was diagnosed with a persimmon gastric bezoar.

In general, delayed gastric emptying, with or without decreased gastric acid secretion, is the mechanism of gastric bezoar formation. A variety of conditions may be predisposing factors, including certain ingested materials such as persimmons, advanced age, diabetic neuropathy, prior gastrectomy history, Crohn disease, gastrointestinal malignancy, dehydration, hypothyroidism, and the use of medications (such as anticholinergics and narcotics) [3,8,9]. In the present study, most patients were of older age, with a mean age of 71.3 years, and 26.7% of the patients (n=4) had a history of intra-abdominal surgery.

We compared the carbonated beverage treatment success and failure groups to evaluate the factors that increased the risk of treatment failure. Although, there was no significant difference between the two groups, the patients who failed the carbonated beverage treatment were older (76.0 years vs. 66.0 years) with larger bezoar sizes (51.9 mm vs. 42.1 mm) than the successful treatment group’s patients. In our study, one patient with a bezoar was asymptomatic (the bezoar was identified during a routine health screening examination), demonstrating that gastric phytobezoars can be observed in asymptomatic patients. However, most patients were symptomatic, with the most common symptoms being epigastric pain (n=7) and bloating (n=6). Several methods, including endoscopy and CT, can be used to diagnose gastrointestinal bezoars. Endoscopy may be the most useful diagnostic method because it allows direct visualization. In CT images, a phytobezoar can be identified as a round mass containing air bubbles. Furthermore, CT is an essential imaging modality, especially when surgery is considered, as it permits visualization of the obstructed segment of the bowel and identification of multiple bezoars [34].

This study had several limitations. First, it was conducted retrospectively in a single center and included a small number of cases. Furthermore, we could not evaluate recurrence rates, as the majority of the patients did not adhere to the recommended follow-up examinations or hospital visits. The relapse rate has been reported to be as high as 14%, especially in patients with psychiatric conditions or gastrointestinal dysmotility [35]. In this study, although only four patients (26.7%) returned for follow-up visits; there was no evidence of recurrence during the 12–35 months following successful treatment.

To prevent the recurrence of gastrointestinal phytobezoars, we recommend not consuming stringy vegetables or persimmons and instructed the patients to chew their food thoroughly. Prokinetics such as erythromycin may be used in patients with gastric dysmotility.

In conclusion, this study demonstrated that 80% of patients with gastric phytobezoars were successfully treated with carbonated beverages alone or in conjunction with additional endoscopic management. However, small bowel obstructions occurred in 20% of the patients due to the migration of a fragmented bezoar. Given the potential for bezoar migration and subsequent complications, clinicians should educate patients about the possibility of bowel obstructions before recommending carbonated beverage treatment, with or without endoscopic treatment. During endoscopic procedures, the fragmented bezoars should be removed, if possible.