A bezoar is a mass of undigested material that accumulates in the gastrointestinal tract, potentially causing complications ranging from abdominal discomfort to intestinal obstruction or perforation. Bezoars are classified into 3 main types based on their composition: trichobezoars, composed of hair and predominantly observed in young women; phytobezoars, formed from plant fibers and more commonly found in adults; and lactobezoars, a rarer but clinically significant type consisting of milk curds in infants (1). Bezoars in infants are rare. Fléchelles et al. (2) reported the largest cluster of 7 cases of lactobezoar in a neonatal intensive care unit. However, the total number of reported cases remains fewer than 100 in the literature to date. Although the majority of infant bezoars are lactobezoars, it has also been reported that pharmacobezoars can be formed from antacids, potassium exchange resin, or sucralfate (3-5).

Here, we present a case of an infant who developed small bowel obstruction due to multiple phytobezoars following the ingestion of synbiotics. Written informed consent was obtained from the patient’s legal guardians for the publication of this case report.

A 3-month-old boy was brought to the emergency department with a 3-day history of vomiting and progressive abdominal distension. The infant was born at 38 weeks 5 days of gestation with a birth weight of 3.5 kg, and had undergone surgery for congenital aganglionic megacolon (also known as Hirschsprung disease) at our institution at 22 days of age. At the presentation, he appeared acutely ill and pale. The initial vital signs were as follows: blood pressure, 80/50 mmHg; heart rate, 160 beats/minute; respiratory rate, 30 breaths/minute; temperature, 36.7 °C; and oxygen saturation, 99% on room air. Physical examination showed abdominal distension with a circumference of 47 cm. Bowel sounds were hyperactive, with the other examinations unremarkable.

During the infant’s postoperative follow-up visit 1 week prior to the abovementioned visit, he was asymptomatic and exhibited age-appropriate growth and development, with both height (60.2 cm) and weight (6.3 kg) between the 25th and 50th percentiles, and an abdominal circumference of 40 cm. He was on standard infant formula and had recently started taking a synbiotic supplement, 1 packet daily, for the 2 previous weeks (Table 1). The parents reported a reduction in his bowel movement frequency following the initiation of synbiotic ingestion.

An initial abdominal plain radiograph showed diffuse dilatation of bowel loops (Fig. 1A). Initial laboratory findings were as follows: leukocytes, 18,700/µL (neutrophils, 57.6%); hemoglobin, 9.8 g/dL; platelets, 615,000/µL; sodium, 132 mmol/L; potassium, 5.0 mmol/L; albumin, 2.7 g/dL; blood urea nitrogen, 12.5 mg/dL; creatinine, 0.14 mg/dL; and C-reactive protein, 20.8 mg/dL. A computed tomography demonstrated a total of 3 bezoars (diameters: 4.1, 3.5, and 3.3 cm) causing small bowel obstruction, without evidence of malrotation, stricture, or stenosis (Fig. 1B).

Due to the infant’s progressive clinical deterioration, surgical exploration was performed on day 2. Intraoperatively, all 3 bezoars were internally obstructing the ileum, and were successfully extracted (Fig. 2). After recovering postoperatively, he was discharged without complications on day 7. Following a thorough discussion with his parents, we decided to discontinue the synbiotic supplement, as well as any other prebiotics or probiotics. During 3 months of follow-up, he remained asymptomatic, with no recurrence of bowel obstruction.

To our knowledge, this is the first documented case of an infant with phytobezoar following a synbiotic ingestion. Although rare in young children, bezoars can lead to bowel obstruction or perforation (6). A high index of suspicion is crucial for diagnosis, particularly in children with a history of consuming high-risk substances. Management depends on the size and location of the bezoar; small or gastric bezoars may respond to chemical dissolution or endoscopic removal, while surgical intervention is required in case of treatment failure or severe complications (7).

The case patient had a history of congenital aganglionic megacolon, a condition associated with reduced bowel motility. However, given the remaining ganglion cells in the ascending colon, an endorectal pull-through procedure had successfully restored continuity between his normally functioning, i.e., ganglionic, bowel segment and the anus. Furthermore, the infant exhibited no signs of constipation and demonstrated age-appropriate growth and development during regular follow-ups. Therefore, we considered his bowel motility to be intact.

We attribute the bezoar formation primarily to the fiber content in the synbiotic supplement which he had consumed, given that some prebiotics may cause bezoar formation. The supplement contained prebiotics, including inulin, fructooligosaccharides, galactooligosaccharides, acacia gum, and resistant maltodextrin. These prebiotic components are highly viscous soluble fibers that can form gel-like masses, potentially forming bezoars (8-10). This mechanism differs from that of traditional phytobezoars, which primarily consist of insoluble plant fibers and tannin polymers (11). Since fiber itself is a key contributing factor in bezoar formation, this current case can be classified as a phyto- or fiber-induced bezoar.

The use of synbiotics has been steadily increasing; therefore, it is crucial to understand their adverse effects. Of the components of synbiotics, probiotics may cause mild gastrointestinal symptoms, such as abdominal discomfort, bloating, or diarrhea, and predispose vulnerable populations to infections (12). Prebiotics, as non-digestible food ingredients, have been widely used in the general population and are generally considered safe. However, recent reports indicate that they may cause dose-dependent gastrointestinal adverse effects (13). As suggested by our case, prebiotics may also contribute to bezoar formation in individuals with certain risk factors, potentially leading to severe complications.

Herein, we reported a case of ileal bezoar formation in a 3-month-old boy following synbiotic ingestion, a rare but serious complication associated with a commonly used supplement in children. This case highlights that in infants with risk factors, clinicians should be aware of the potential adverse effect of synbiotics. Further research is warranted to establish age-specific guidelines for the optimal type and dose of fiber that will maximize the safety and efficacy of synbiotic use in pediatric population.