HYPOChLorous Acid TEsting Studies in Percutaneous DRAINAGE (HYPOCLATES:DRAINAGE): Protocol for a Single-Centre, Controlled, Ambispective Cohort Study Comparing Hypochlorous Acid Versus Saline Irrigation in Percutaneous Drainage of Intra-Abdominal Abscesses.

Introduction Percutaneous drainage is the standard of care for intra-abdominal abscesses. Additional saline irrigation provides mechanical cleansing but lacks antimicrobial activity. Hypochlorous acid (HOCl), an endogenous antiseptic with broad-spectrum microbicidal activity and high tissue compatibility, is a promising alternative for intracavitary infection control. This study evaluates whether HOCl irrigation shortens the indwelling time of percutaneous irrigation drains and systemic antibiotic duration compared with saline irrigation in patients with intra-abdominal abscesses.Methods and analysis Following an institutional change in routine practice on 1 December 2025, this single-centre, controlled, ambispective cohort study at the Department of General, Visceral and Transplantation Surgery, Heidelberg University Hospital, compares a prospectively followed cohort treated with continuous HOCl-containing irrigation (Granudacyn) with a non-concurrent, retrospectively assembled saline cohort from the preceding period. Both cohorts include drains managed with continuous high-volume irrigation (at least 1 L per 24 h for a minimum of 3 consecutive days). The primary endpoints are the indwelling time of the index irrigation drain (placement to removal) and the duration of systemic antibiotic therapy. Secondary endpoints include hospital and intensive care unit stay, reinterventions, complication severity (Clavien–Dindo), time to fistula closure and infection-related parameters. Confounding is addressed using propensity-score methods, and time-to-event endpoints are analysed accounting for competing events.Ethics and dissemination The study has received ethical approval from the Ethics Committee of Heidelberg University’s Medical Faculty (S-520/2025). As pseudonymised routine clinical data are used without additional patient contact or deviation from standard care, individual informed consent is waived in accordance with the national regulations and General Data Protection Regulation. Study findings will be disseminated through peer-reviewed publications.Trial registration number DRKS00038653.