Author response: Effect of peritoneal and wound lavage with super-oxidized solution on surgical-site infection after open appendicectomy in perforated appendicitis (PLaSSo): randomized clinical trial

After suctioning and swabbing the peritoneal cavity to remove pus and slough, normal saline lavage was performed until a clear effluent was achieved, in accordance with our standard institutional protocol. The study solution was then used for the final peritoneal lavage and allowed to soak for 3 min before being suctioned until dry. This method was intended to maximize the bactericidal effect of the super-oxidized solution rather than serve as a means of decontamination from pus or slough. Therefore, the volume of the solution was calculated based on body-weight to ensure adequate coverage of the peritoneal cavity, irrespective of the degree of contamination. This pragmatic approach was designed for ease of replication in daily clinical practice.

For simplicity, intraoperative contamination was classified as peri-appendiceal, pelvic, or generalized: the latter defined as the presence of pus or slough beyond the right iliac fossa and pelvis. In our study, contamination was similarly distributed between groups, with 15.7% peri-appendiceal, 73.5% pelvic, and 10.8% generalized contamination. It is important to note that patients presenting with significant peritoneal contamination with generalized peritonitis would have undergone a midline laparotomy rather than a Lanz incision.

A subgroup analysis comparing the degree of contamination with the incidence of surgical site infection did not reveal any significant differences, and the study was underpowered to detect differences within these subgroups.

Although this study was conducted in Malaysia—a country known for its diverse multi-ethnic population, including Malay, Chinese, Indian, and indigenous groups—we acknowledge the need for an international, multi-centre study to further validate the outcomes of the PLaSSo trial.

Thank you for engaging with our team. We hope this response clarifies our methodology and justifies the study protocol.

Sincerely,

The PLaSSo Trial Group