Hammond 2008.

Methods	Randomised trial. Envelope randomisation
Participants	20 (mean age control = 50 years (22 to 70 years), mean age intervention = 43 (21 to 69 years)), Male 7:13 Female
Interventions	Conventional loop ileostomy via a trephine incision (n = 10) vs loop ileostomy with a 10 x 10 cm Permacol mesh with a 2‐centimetre cylindrical defect cut in the centre (n = 10)
Outcomes	The incidence of parastomal hernia was assessed by ultrasound scan (16 of 20 trial participants). Incidence of infection and seroma assessed by laboratory tests and ultrasound scan. Incidence of patient symptoms assessed by a questionnaire.
Length of Follow Up	Maximum 12 months (if no reversal) Maximum 6.5 months (if stoma reversed)
Notes	No participants lost to follow‐up
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Comment: Participants were randomised using consecutively numbered, sealed envelopes. No random sequence generation
Allocation concealment (selection bias)	Low risk	Quote: "consecutively numbered sealed envelopes" Comment: Probably occurred
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: Not possible to blind the surgeon as to which procedure was being performed
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "underwent a clinical examination for signs of a parastomal hernia" Comment: No evidence of assessor blinding when performing clinical examination
Incomplete outcome data (attrition bias) All outcomes	Low risk	No participants lost to follow‐up. No complete 12‐month data. Appropriately outlined follow‐up regimen
Selective reporting (reporting bias)	Low risk	Quote: "Patients were followed‐up until the time of stoma reversal or, in the event of the stoma not being reversed, until 12 months after stoma formation." Comment: No selective reporting. All participants and outcomes accounted for.
Early Stopping	Low risk	No early stopping