THE MANAGEMENT OF OBSTETRIC ANAL SPHINCTER INJURY (EVIDENCE BASED) Dr. Ashraf Fouda Ob./Gyn. Consultant Damietta General Hospital

Sources of Guidelines The Cochrane Library. Medline and PubMed . UpToDate ® August 2006 . RCOG March 2007, THE MANAGEMENT OF THIRD- AND FOURTH-DEGREE PERINEAL TEARS . RCOG June 2004 , METHODS AND MATERIALS USED IN PERINEAL REPAIR . American Family Physician October 2003 .

Muscles of perineal body

Applied anatomy The anal canal measures about 3.5 cm in length. The external anal sphincter (EAS) is striated muscle and is subdivided into subcutaneous, superficial and deep regions and is responsible for voluntary squeeze and reflex contraction pressure It is innervated by the pudendal nerve

Applied anatomy The internal anal sphincter (IAS) is a thickened continuation of the circular smooth muscle of the bowel. It contributes about 70% of the resting pressure and is under autonomic control.

Introduction Obstetric anal sphincter injury includes both third- and fourth-degree perineal tears.

Introduction The overall risk of obstetric anal sphincter injury is 1% of all vaginal deliveries. This condition may also present in women without obvious anal sphincter tears during labour and delivery (occult injury).

Importance Anal incontinence is defined as any involuntary loss of faeces, flatus or urge incontinence that is adversely affecting a woman’s quality of life. Up to 40% of women with third or fourth degree perineal tears during childbirth suffer from anal incontinence.

Classification and terminology of perineal tears by International Consultation on Incontinence and the RCOG. First degree Injury to perineal skin only. Second degree Injury to perineum involving perineal muscles but not involving the anal sphincter. Third degree Injury to perineum involving the anal sphincter complex (EAS and IAS) : 3a: Less than 50% of EAS thickness torn. 3b: More than 50% of EAS thickness torn. 3c: Both EAS and IAS torn. Fourth degree Injury to perineum involving the anal sphincter complex and anal epithelium.

THIRD DEGREE PERINEAL TEAR FOURTH-DEGREE PERINEAL TEAR

Risk factors for obstetric anal sphincter injury Birth weight over 4 kg Persistent occipitoposterior position Nulliparity Induction of labour Epidural analgesia Second stage longer than 1 hour Shoulder dystocia Midline episiotomy Forceps delivery

Prediction and prevention of obstetric anal sphincter injury When episiotomy is indicated, the mediolateral technique is recommended, with careful attention to the angle cut away from the midline. Grade B

Prediction and prevention of obstetric anal sphincter injury With introduction of endoanal ultrasound, sonographic abnormalities of the anal sphincter anatomy has been identified in up to 36% of women after vaginal delivery, in prospective studies. A lower risk of third-degree tear is associated with a larger angle of episiotomy.

Normal anal ultrasound

How can the identification of obstetric anal sphincter injuries be improved? 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. Grade B

Surgical techniques 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. (Grade A)

End-to-end (approximation) method Overlap technique

Surgical techniques A systematic review on the method of repair showed that no significant difference in: perineal pain ,dyspareunia ,flatus incontinence and faecal incontinence & quality of life between the two repair techniques at 12 months But showed a significantly lower incidence in faecal urgency in the overlap group. (Grade A)

Surgical techniques Repair in an operating theatre will allow the repair to be performed under aseptic conditions with appropriate instruments, adequate light and an assistant. Regional or general anaesthesia will allow the anal sphincter to relax, which is essential to retrieve the retracted torn ends of the sphincter without any tension (Grade C)

Choice of suture materials The use of absorbable synthetic material polyglactin 910 (vicryl) when compared with catgut, is associated with less : Perineal pain, Analgesic use, Dehiscence and Resuturing, but increased suture removal. (Grade A)

Choice of suture materials The use of a more rapidly absorbed form of polyglactin 910 (Vicryl®) is associated with a significant reduction in pain and a reduction in suture removal when compared with standard absorbable synthetic material. In the light of current evidence, rapid-absorption polyglactin 910 (Vicryl®) is the most appropriate suture material for perineal repair. (Grade A)

Choice of suture materials 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. Burying of surgical knots beneath the superficial perineal muscles is recommended to prevent knot migration to the skin. (Grade C) (Good practice point)

Method of repair A loose, continuous non-locking suturing for (vaginal tissue, perineal muscle and skin) & the use of a continuous subcuticular technique for perineal skin closure is associated with less short term pain than techniques employing interrupted sutures. (Grade A)

Surgical competence Obstetric anal sphincter repair should be performed by appropriately trained practitioners. Formal training in anal sphincter repair techniques, is recommended as an essential component of obstetric training. (Good practice point)

Postoperative management The use of broad-spectrum antibiotics is recommended to reduce the incidence of postoperative infections and wound dehiscence. The use of postoperative laxatives is recommended to reduce the incidence of postoperative wound dehiscence. (good practice point) (Grade C)

Postoperative management All women who have had obstetric anal sphincter repair should be : Offered physiotherapy and pelvic-floor exercises for 6–12 weeks after repair. Reviewed 6–12 weeks postpartum by a consultant obstetrician and gynaecologist. (good practice point)

Prognosis 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. (Grade A)

Future deliveries All women with an obstetric anal sphincter injury in a previous pregnancy should be : Counselled about the risk of developing anal incontinence or worsening symptoms with subsequent vaginal delivery. Advised that there is no evidence to support the role of prophylactic episiotomy in subsequent pregnancies. (good practice point)

Future deliveries All women with an obstetric anal sphincter injury in a previous pregnancy and who are symptomatic or have abnormal endoanal ultrasonography should have the option of elective caesarean birth. (good practice point)

Risk management There is a steady increase in litigation related to obstetric anal sphincter injury. Litigation is related to failure to identify the injury after delivery, leading to subsequent anal incontinence and rectovaginal fistulae. Poor technique, poor materials or poor healing may cause a repair to fail.

Practice recommendations Avoiding obstetrical injury to the anal sphincter is the single biggest factor in preventing anal incontinence . Any form of instrumental delivery has been noted to increase the risk of obstetric anal sphincter injury and altered fecal continence , by between 2-7 fold .

Practice recommendations Routine episiotomy is not recommended. Episiotomy use should be restricted to situations where it directly facilitates an urgent delivery . A mediolateral incision, instead of a midline, should be considered for persons at high risk of obstetric anal sphincter injury ,with careful attention to the angle cut away from the midline.

Practice recommendations The internal anal sphincter needs to be separately repaired, if torn . Women with injuries to the internal anal sphincter or rectal mucosa have a worse prognosis for future continence problems .

Practice recommendations All women, especially those with risk factors for injury, should be surveyed for symptoms of anal incontinence at postpartum follow-up .

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