Rapidly accumulating ascites as an early clue to encapsulating peritoneal sclerosis.

Early identification of encapsulating peritoneal sclerosis (EPS) remains challenging, particularly in the absence of definitive radiological signs. We report a case of a 69-year-old male with end-stage kidney disease on peritoneal dialysis (PD) for 9 years, who developed poor appetite and weight loss. After complete drainage of ascites, PD was ceased for 1 day, during which 500 mL of newly formed ascites accumulated. Ascitic interleukin-6 and CA-125 levels were markedly elevated, raising concern for evolving EPS. Although computed tomography showed bowel dilatation and focal peritoneal thickening without calcification or a fibrous cocoon, the ongoing production of fibrin-rich ascites and weight loss prompted a transition to hemodialysis (HD) and corticosteroid treatment. After transitioning to HD, the volume of weekly drained ascites decreased slowly, and his appetite and weight began to recover. This case highlights that rapidly accumulating ascites following a brief cessation of PD may serve as an early and clinically meaningful marker of EPS development, especially in high-risk individuals. Timely recognition of this subtle manifestation could enable earlier intervention and improve outcomes.