Do 2005.

Methods	Parallel‐group randomised controlled trial. Single centre, Hallym University Kangdong Sacred Heart Hospital, Seoul, South Korea. Protocol approved by IRB: not reported; no contact possible due to absence of contact details. Statistical power calculation not reported; no contact possible due to absence of contact details. External funding and conflicts of interest not reported; no contact possible due to absence of contact details.
Participants	Number recruited: 64 women. Number randomly assigned: 64 women. Number excluded: 2 women, reason for exclusion not reported. Number lost to follow‐up: 0 women. Number analysed: 62 women. Inclusion criterion: aged 20‐44 years. Exclusion criteria: women wishing to become pregnant within 1 month after intrauterine surgery; severe liver or renal disease; coagulation disorders or under treatment with anticoagulant drugs; diabetes; autoimmune disease. Proportion of women with infertility: unclear if infertile women were included or excluded. Study duration of study: 10 months. Mean age (range): 28 (22‐43) years. Mean age in intervention group: 26 years. Mean age in control group: 31 years.
Interventions	HA/CMC gel (intervention: n = 32) vs saline (control: n = 30) Intervention group: after intrauterine surgery, 10 mL of HA + CMC applied on uterine cavity. Control group: 10 mL of saline applied. After surgery, antibiotics injected for 1 day, and then oral antibiotics administered for 3 days. Women who underwent dilatation and curettage were discharged on 1st postoperative day, and women who underwent hysteroscopy were discharged on 2nd postoperative.
Outcomes	Frequency and severity of IUAs compared by microhysteroscopy on 4th postoperative week, severity of IUAs classified in accordance with AFS 1988 guidelines.
Notes	No contact data of the primary study authors reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Patients were randomized to 32 patients of study group (group A) and 32 patients of control group (group B) each." Comment: method not described; unclear if stratified randomisation was used; no contact possible.
Allocation concealment (selection bias)	Unclear risk	Method of allocation concealment not described; no contact possible.
Blinding of participants and personnel (performance bias) Live birth, pregnancy or miscarriage	Low risk	Quote: "After intrauterine surgery, in group A [intervention], 10ml of Hyaluronic acid + Sodium Carboxymethyl Cellulose (HA + CMC) was applied on uterine cavity, and in group B [control], 10ml of saline was applied." Comment: surgeons not blinded; easy to distinguish saline from gel.
Blinding of participants and personnel (performance bias) Adhesions	High risk	Quote: "After intrauterine surgery, in group A, 10ml of Hyaluronic acid + Sodium Carboxymethyl Cellulose (HA + CMC) was applied on uterine cavity, and in group B, 10ml of saline was applied." Comment: surgeons not blinded; easy to distinguish saline from gel.
Blinding of outcome assessment (detection bias) Live birth, pregnancy or miscarriage	Low risk	Not reported if gynaecologists who performed second‐look procedure 4 weeks after surgery were blinded or not; no contact possible.
Blinding of outcome assessment (detection bias) Adhesions	Unclear risk	Not reported if gynaecologists who performed second‐look procedure 4 weeks after surgery were blinded or not; no contact possible.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "In total 64 patients, 62 patients were followed up postoperatively. Group A was 32 patients, Group B was 30 patients, and 2 patients were excluded during study." Comment: reasons for postrandomisation exclusion not reported.
Selective reporting (reporting bias)	Low risk	Comment: no evidence of selective outcome reporting when abstract, methods and results were compared.
Other bias	High risk	Quote: "See table of baseline characteristics Age in years group A [intervention]: 26 Age in years group B [control]: 31 Parity in group A: 0.8 Parity in group B: 1.5 Abortion in group A: 1.0 Abortion in group B: 1.8." Comment: high risk of selection bias. Quote: "As a result of transvaginal sonography, intrauterine adhesion was observed at 4 patients (13%) out of 32 patients in group A and had mild intrauterine adhesions." Comment: unclear if micro‐hysteroscopy or transvaginal ultrasound used for outcome assessment of IUAs. High risk of information bias.