Obstetric Anal Sphincter Injury- A guideline. Mr David Sim Ms Patricia McStay. Dr Martina Hogan Dept./Division Only: YES-IMWH Directorate Only: NO

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1 CLINICAL GUIDELINES ID TAG Title: Obstetric Anal Sphincter Injury- A guideline Author: Dr Foteini Verani Designation: Specialist Doctor Speciality / Division: Obstetrics-IMWH Directorate: Acute Services Date: November 2017 Consulted upon: Yes Authorised by Approved by: (Name of AMD) Applicable to: (delete Yes / No as appropriate) Review Date (Every 2 years or sooner if required): Mr David Sim Ms Patricia McStay Dr Martina Hogan Dept./Division Only: YES-IMWH Directorate Only: NO November 2020 Trust-wide: NO Clinical Guidelines ID: CG0131[1]

2 Obstetric Anal Sphincter Injury- A guideline Introduction The overall risk of Obstetric Anal Sphincter injury (OASIS) in the UK is 2.9%. In instrumental deliveries it occurs in 12%-15% of cases. Classification of OASIS and terminology Third Degree Injury to the 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 Fourth Degree disruption of the anal sphincter muscles with a breach of the rectal mucosa. Rectal buttonhole tear is the tear that involves the rectal mucosa with an intact anal sphincter complex. Anal incontinence is defined as the complain of involuntary loss of flatus and/or faeces affecting quality of life. If there is any doubt sought about the degree of tear, it is advisable to classify in the higher degree Risk factors Asian ethnicity Nulliparity Birth weight > 4Kg Shoulder dystocia OP position Prolonged 2nd stage Instrumental delivery However, the risk factors do not allow the accurate prediction of OASIS Prevention Clinicians should explain to women that the evidence for the protective effect of episiotomy is conflicting.

3 Mediolateral episiotomy (60 degrees away from midline when the perineum is distended) should be considered in instrumental deliveries. The use of episcissors has been shown to be effective in achieving the correct angle. Perineal protection at crowning and warm compression during the 2nd stage of labour can also be protective. Identification of OASIS Obstetric perineal injury should be examined by an experienced practitioner trained in recognition and management of perineal tears. The full extent of the injury should be evaluated by a careful vaginal and rectal examination with adequate lighting The tear should be classified as above and fully documented, preferably pictorially. Preparation All repairs should be conducted by an appropriately trained clinician or a trainee under supervision in a place where there is good lighting, appropriate equipment and aseptic conditions can be implemented. Repair in the delivery room may be performed after discussion with senior obstetrician. Use the Third degree perineal tear repair pack, which has been specially prepared for this purpose. Effective epidural or spinal anaesthetic is recommended. Surgical technique The torn anorectal mucosa must be repaired with interrupted or continuous with 3/0 vicryl IAS should be repaired separately by end-to-end approximation with interrupted or mattress without any attempt to overlap the IAS. For repair of a full thickness external anal sphincter (EAS) tear, either an overlapping or an end-to-end (approximation) method can be used with equivalent outcomes. For partial thickness (all 3a and some 3b) tears, an end-toend technique should be used.

4 When repair of the EAS and/or IAS muscle is being performed, either monofilament sutures such as 3-0 PDS or modern braided sutures such as 2-0 vicryl can be used with equivalent outcomes. Great care must be exercised in reconstructing the perineal muscles to provide support and ensure that the knots are completely buried with overlying tissue to avoid migration. Figure of eight sutures should be avoided because they are haemostatic and may cause tissue ischaemia. A rectal examination should be performed after the repair to ensure that sutures have not been inadvertently inserted through the anorectal mucosa. If a suture is identified it should be removed. Post Procedure Careful and detailed note keeping is essential as the consequences of anal sphincter disruption can result in litigation. Use the diagram in the perineal repair sheet in the Maternity Chart or use the Third or fourth degree tear repair proforma to demonstrate the extent of the injury and technique of repair as it will serve to substantiate that a careful examination was performed. Broad-spectrum antibiotics are recommended as per Hospital Antibiotic Guideline. Stool softeners: Lactulose 10-15mls BD for 10 days to avoid constipation Bulking agents like Fybogel should not be given routinely with laxatives. Analgesia: Ensure adequate analgesia, such as diclofenac 50mg PO TDS is given. Avoid codeine containing analgesia as this causes constipation. Follow up Women should be fully informed about the nature of her injury and the benefits to her of follow up. This should include written information where possible. (Patient information: -

5 Advice should be given to seek help if any concerns about infection or bowel control. Physiotherapy: All women should be offered physiotherapy and pelvic-floor exercises for 6-12 weeks after obstetric anal sphincter repair. GOPD review: All women should be reviewed by a consultant 6-12 weeks postpartum at a Gynae Out-Patients appointment or Postnatal clinic. If a woman is experiencing incontinence or chronic pain at follow-up, referral to colorectal surgeon should be considered. If a woman is experiencing incontinence or chronic pain at follow-up referral for endoanal ultrasonography should be considered only if appropriate. Prognosis: 60-80% of women are asymptomatic after 12 months. Future deliveries: All women should be counselled about the mode of delivery and this should be clearly documented in the notes. The risk of recurrence of a 3 rd /4 th degree tear is 5-7%. There is no evidence that prophylactic episiotomy prevents OASIS. Caesarean section should be discussed if the woman is symptomatic or have abnormal endoanal ultrasonography and/or manometry. References 1. Royal College of Obstetricians and Gynaecologists. Management of Third- and Fourth-Degree Perineal Tears RCOG Press: June RCOG Guideline No Croydon Health Services NHS Trust. Maternity Guideline Management of 3 rd /4 th Degree Tears. Version 3.0 Thakar R, Sultan A. May Southern Health and Social Care Trust Antibiotic Policy. 4. Sultan AH, Thakar R, Fennar DE. Perineal & Anal Sphincter Trauma. London: Springer Press. 2007