The grades of evidence (I-III) and levels of recommendations (A-C) are defined at the end of the "Major Recommendations" field
The following recommendation and conclusion are based on good and consistent scientific evidence (Level A):
- Restricted use of episiotomy is preferable to routine use of episiotomy.
- Median episiotomy is associated with higher rates of injury to the anal sphincter and rectum than is mediolateral episiotomy.
The following recommendation and conclusion are based on limited or inconsistent scientific evidence (Level B):
- Mediolateral episiotomy may be preferable to median episiotomy in selected cases.
- Routine episiotomy does not prevent pelvic floor damage leading to incontinence.
Grades of Evidence
I: Evidence obtained from at least one properly designed randomized controlled trial.
II-1: Evidence obtained from well-designed controlled trials without randomization.
II-2: Evidence obtained from well-designed cohort or case–control analytic studies, preferably from more than one center or research group.
II-3: Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments also could be regarded as this type of evidence.
III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
Levels of Recommendations
Level A — Recommendations are based on good and consistent scientific evidence.
Level B — Recommendations are based on limited or inconsistent scientific evidence.
Level C — Recommendations are based primarily on consensus and expert opinion.