This is a prospective randomized single-blind study where a placebo group served the control, to confirm the efficacy and safety of AdSpray™ as an inhibitory effect of postoperative adhesion formation in paediatric patients who underwent laparotomy with stoma.

Postoperative adhesions are fibrovascular bands connecting the parietal peritoneum to the visceral peritoneum of intra-abdominal organs, or connecting intra-abdominal organs to one another, which developed unavoidably following virtually all body cavity surgeries. Adhesions affect up to 80-93% of patients following abdominal surgery. Being the leading cause of postoperative small bowel obstruction, it could potentially cause other enormous clinical problems including difficulty in subsequent operations, infertility, and chronic pain. The incidence of adhesion-related morbidity is estimated to be 2.2% to 19.5% in the pediatric population, among which large proportion of patients required subsequent surgical intervention. A variety of techniques and products (e.g. bioresorbable physical barrier agents, pharmacological adjuncts, etc) have been advocated for preventing postoperative adhesion formation. However, to date, no single treatment is proven to be effective and adhesions still remain a significant, unresolved postoperative complication both in adults and paediatric populations.

To reduce postoperative adhesions, Terumo Corporation (Tokyo, Japan) has developed an adhesion barrier system (AdSpray™; Terumo Corporation, Tokyo, Japan) which is easy to use at the treatment site in various surgical procedures. Its ability of adhesion prevention had been demonstrated in porcine model study. Cezar et al and Suto et al subsequently published two human prospective randomized controlled trials on the use of this barrier system in adult patients undergoing gynaecological and gastrointestinal operations, which confirmed its safety and efficacy. However, to date, studies on the use of anti-adhesion agents in children are scarce and there is no study on this novel barrier system (AdSpray™) in children. In view of this, we plan to conduct a prospective randomized single-blind study where a placebo group served the control, to confirm the efficacy and safety of AdSpray™ as an inhibitory effect of postoperative adhesion formation in paediatric patients who underwent laparotomy with stoma.

B. Study objective To investigate the effect of a novel spray-type, novel dextrin hydrogel adhesion barrier (AdSpray™; Terumo Corporation, Tokyo, Japan) on postsurgical adhesions.

C. Study design and methods This is a prospective, single center, single-blinded randomized controlled trial using a parallel arm design and placebo group as the control. Patient enrollment will start in March 2022 and expected to end in 2023.

Inclusion Criteria:

• Patients requiring laparotomy and staged operation with closure of stoma as second operation e.g. Necrotising Enterocolitis, Anorectal malformation, Hirschsprung's disease, etc.

Exclusion Criteria:

• A history of hypersensitivity to substances derived from corn starch
• A history of surgery in the abdominal cavity or pelvic cavity accompanied by a laparotomy scar
• Patients with peritonitis
• Laparoscopic assessment of adhesions may not be performed safely at the second-look surgery.

After completion of necessary operative procedures in the primary operation, barrier agent (AdSpray™or Placebo) will be sprayed to fully cover the organs under the laparotomy incision. At the second-look surgery, laparoscopic video recordings of the area under the laparotomy incision will be made in both groups. For the efficacy evaluation, based on the laparoscopic images of the abdominal cavity at the time of the second-look surgery, the presence, extent, and severity of adhesions will be assessed by the adhesion-assessment team which is independent of the study. The independent adhesion-assessment team will assess the extent and severity of adhesions under the laparotomy incision on a 4-grade scale.