Boulos 1984.
| Methods | Randomized controlled trial | |
| Participants | Patients with chronic anal fissure | |
| Interventions | Open (14) versus subcutaneous (14) partial lateral internal sphincterotomy | |
| Outcomes | Persistence of the fissure and incontinence to flatus | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | pulling classification cards once surgery had been determined to be necessary |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | inadequate |
| Drop‐outs All outcomes | Low risk | zero |