Esophageal bezoar formation following enteral nutrition

Esophageal bezoars caused by enteral nutrition are rare but may occur when casein-containing formulas solidify under conditions of impaired esophageal clearance. We report a case of complete esophageal obstruction associated with short-term postoperative enteral feeding. A 27-year-old man developed dysphagia and nasogastric tube obstruction after 5 days of nasogastric administration of a casein-based enteral formula following cardiothoracic surgery. Upper endoscopy revealed a large, whitish bezoar completely filling the esophageal lumen. Partial endoscopic fragmentation was achieved, and most of the mass was successfully dislodged into the stomach, enabling reinsertion of the feeding tube. The patient recovered uneventfully, and no recurrence was observed after switching to a peptide-based formula. To explore potential contributing factors, an in vitro experiment was conducted to assess the behavior of the casein-based formula under acidic conditions. The formula remained liquid when mixed with solutions at pH 2.0-5.5 but rapidly solidified under extreme acidic conditions (pH 1.0). In contrast, rapid solidification occurred upon mixing with a pH 1.0 solution. These findings suggest that casein-containing formulas may undergo coagulation under certain physicochemical conditions; however, bezoar formation in this case was likely multifactorial, involving transient postoperative esophageal stasis, impaired clearance, and formula retention rather than sustained exposure to highly acidic gastric juice alone. This case also highlights that even transient postoperative esophageal stasis can precipitate bezoar formation when casein-containing enteral nutrition is administered.