In addition to these evidence-based recommendations, the guideline development group also identifies points of best clinical practice in the original guideline document.
Levels of evidence (Ia-IV) and grading of recommendations (A-C) are defined at the end of the "Major Recommendations" field.
Prediction and Prevention of Obstetric Anal Sphincter Injury
Can Obstetric Anal Sphincter Injury Be Predicted and Prevented?
B - Where episiotomy is indicated, the mediolateral technique is recommended, with careful attention to the angle cut away from the midline.
Risk factors for third-degree tears have been identified in a number of retrospective studies. Taking an overall risk of 1% of vaginal deliveries, the following factors are associated with an increased risk of a third-degree tear:
- Birth weight over 4 kg (up to 2%)
- Persistent occipitoposterior position (up to 3%)
- Nulliparity (up to 4%)
- Induction of labour (up to 2%)
- Epidural analgesia (up to 2%)
- Second stage longer than 1 hour (up to 4%)
- Shoulder dystocia (up to 4%)
- Midline episiotomy (up to 3%)
- Forceps delivery (up to 7%)
Classification and Terminology
How Should Obstetric Anal Sphincter Injury Be Classified?
C - It is recommended that the classification outlined in this guideline be used when describing any obstetric anal sphincter injury.
The following classification, described by Sultan*, has been adopted by the International Consultation on Incontinence and the Royal College of Obstetricians and Gynaecologists. (Evidence level IV)
*Sultan AH, Editorial: obstetric perineal injury and anal incontinence. Clin Risk 1999;5:178-80.
||Injury to perineal skin only
||Injury to perineum involving perineal muscles but not involving the anal sphincter
||Injury to perineum involving the anal sphincter complex:
3a: Less than 50% of external anal sphincter (EAS) thickness torn
3b: More than 50% of EAS thickness torn
3c: Both EAS and internal anal sphincter (IAS) torn
||Injury to perineum involving the anal sphincter complex (EAS and IAS) and anal epithelium.
If the tear involves only anal mucosa with intact anal sphincter complex (buttonhole tear), this has to be documented as a separate entity. If not recognised and repaired, this type of a tear may cause anovaginal fistulae.
Identification of Obstetric Anal Sphincter Injuries
How Can the Identification of Obstetric Anal Sphincter Injuries Be Improved?
C - All women having a vaginal delivery with evidence of genital tract trauma should be examined systematically to assess the severity of damage prior to suturing.
Which Techniques Should Be Used to Accomplish the Repair of Obstetric Anal Sphincter Injury?
A - For repair of the external anal sphincter, either an overlapping or end-to-end (approximation) method can be used, with equivalent outcome. Where the IAS can be identified, it is advisable to repair separately with interrupted sutures.
Repair of third- and fourth-degree tears should be conducted in an operating theatre, under regional or general anaesthesia.
Choice of Suture Materials
Which Suture Materials Should Be Used to Accomplish Repair of Obstetric Anal Sphincter Injuries?
A - When repair of the EAS muscle is being performed, either monofilament sutures such as polydiaxanone (PDS) or modern braided sutures such as polyglactin (Vicryl®) can be used with equivalent outcome.
C - When repair of the IAS muscle is being performed, fine suture size such as 3-0 PDS and 2-0 Vicryl may cause less irritation and discomfort.
How Should Women With Obstetric Anal Sphincter Injury Be Managed Postoperatively?
C - The use of postoperative laxatives is recommended to reduce the incidence of postoperative wound dehiscence.
A systematic review addressing the antibiotic prophylaxis for fourth-degree perineal tear comparing prophylactic antibiotics with placebo or no antibiotics did not find any randomised controlled trials. However intraoperative and postoperative broad-spectrum antibiotics are recommended because the development of infection will pose a high risk of anal incontinence and fistula formation in the event of breakdown of the anal sphincter repair. Inclusion of metronidazole is advisable to cover the possible anaerobic contamination from faecal matter. (Evidence level IV)
There were no systematic reviews or randomised controlled trials to suggest the best method of follow-up after obstetric anal sphincter repair. It is helpful to review women in the postnatal period to discuss injury sustained during childbirth, assess for symptoms, and offer advice on how to seek help if symptoms develop, offer treatment and/or referral if indicated and advice on future mode of delivery.
If facilities are available, follow-up of women with obstetric anal sphincter injury should be in a dedicated perineal clinic with access to endoanal ultrasonography and anal manometry, as this can aid decision on future delivery. (Evidence level IV)
What Is the Prognosis Following Surgical Repair?
A - Women should be advised that the prognosis following EAS repair is good, with 60–80% asymptomatic at 12 months. Most women who remain symptomatic describe incontinence of flatus or faecal urgency.
What Advice Should Women Be Given Following an Obstetric Anal Sphincter Injury Concerning Future Pregnancies and Mode of Delivery?
All women who have suffered an obstetric anal sphincter injury should be counselled at the booking visit regarding the mode of delivery and this should be clearly documented in the notes. If the woman is symptomatic or shows abnormal anorectal manometric or endoanal ultrasonographic features, it may be advisable to offer an elective caesarean section.
What Processes and Policies Should Be in Place for Women Who Have Sustained Obstetric and Sphincter Injury?
There is a steady increase in litigation related to obstetric anal sphincter injury. The majority are related to failure to identify the injury after delivery, leading to subsequent anal incontinence and rectovaginal fistulae. At present, the occurrence of obstetric anal sphincter injury is not considered substandard care because it is a known complication of vaginal delivery. However, failure to recognise anal sphincter damage and to carry out a repair may be considered substandard care. Poor technique, poor materials or poor healing may cause a repair to fail. Clear documentation and patient counselling are of utmost importance. A patient information leaflet is recommended.
Grading of Recommendations
Grade A - Requires at least one randomised controlled trial as part of a body of literature of overall good quality and consistency addressing the specific recommendation. (Evidence levels Ia, Ib)
Grade B - Requires the availability of well controlled clinical studies but no randomised clinical trials on the topic of recommendations. (Evidence levels IIa, IIb, III)
Grade C - Requires evidence obtained from expert committee reports or opinions and/or clinical experiences of respected authorities. Indicates an absence of directly applicable clinical studies of good quality. (Evidence level IV)
Levels of Evidence
Ia: Evidence obtained from meta-analyses of randomised controlled trials
Ib: Evidence obtained from at least one randomised controlled trial
IIa: Evidence obtained from at least one well-designed controlled study without randomisation
IIb: Evidence obtained from at least one other type of well-designed quasi-experimental study
III: Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies, and case studies
IV: Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities