This case presents an 18-year-old male patient with a complex  five-year history of intermittent rectal bleeding, marked by recurrent symptoms and mutiple failed surgical interventions, culminating in a diagnosis of Mucosal Prolapse Syndrome (MPS) following the exclusion of other potential benign and malignant pathologies.

The patient ultimately underwent underwater endoscopic mucosal resection (UEMR) was successfully cured. UEMR enables rapid and precise mucosal resection while significantly minimizing electrical injury, thereby safeguarding adjacent tissues and effectively mitigating the risk of complications such as delayed bleeding or stricture formation.

The patient’s postoperative recovery was uneventful, with no recurrence of symptoms at three-month and six-month follow-ups.