Introduction: Hemorrhagic cystitis (HC) is a common complication after allogeneic hematopoietic stem cell transplantation (HSCT), characterized by inflammation and bleeding of the bladder. Hyperbaric oxygen therapy (HBOT) has been shown to be effective in the treatment of radiation-induced HC. However, the optimal treatment for HC after allogeneic HSCT has not yet been established. Furthermore, limited research...