News for Your Practice

Obstetric anal sphincter injury: 7 critical questions about care

OBG Manag. 2008 February;20(2):56-68

References

1. Sultan AH, Kettle C. Diagnosis of perineal trauma. In: Sultan AH, Thakar R, Fenner DE, eds. Perineal and Anal Sphincter Trauma. London: Springer; 2007:13-19.

2. Sultan AH, Thakar R. Third and fourth degree tears. In: Sultan AH, Thakar R, Fenner DE, eds. Perineal and Anal Sphincter Trauma. London: Springer; 2007:33-51.

3. Sultan AH. Primary repair of obstetric anal sphincter injury. In: Staskin DR, Cardozo L, ed. Textbook of Female Urology and Urogynaecology. London: ISIS Medical Media; 2006.

4. Thakar R, Fenner DE. Anatomy of the perineum and the anal sphincter. In: Sultan AH, Thakar R, Fenner DE, eds. Perineal and Anal Sphincter Trauma. London: Springer; 2007:1-12.

5. Faltin DL, Boulvain M, Floris LA, Irion O. Diagnosis of anal sphincter tears to prevent fecal incontinence: a randomized controlled trial. Obstet Gynecol. 2005;106:6-13.

6. Andrews V, Thakar R, Sultan AH. Occult anal sphincter injuries—myth or reality. Br J Obstet Gynaecol. 2006;113:195-200.

7. Sultan AH. Obstetric perineal injury and anal incontinence. Clin Risk. 1999;5:193-196.

8. Royal College of Obstetricians and Gynaecologists. Management of third and fourth degree perineal tears following vaginal delivery. Guideline 29. London: RCOG Press; 2001.

9. Norton C, Christensen J, Butler U, et al. Anal Incontinence. 2nd ed. Plymouth: Health Publication Ltd; 2005:985-1044.

10. Sultan AH, Thakar R. Lower genital tract and anal sphincter trauma. Best Pract Res Clin Obstet Gynaecol. 2002;16:99-116.

11. Williams A, Adams EJ, Tincello DG, Alfirevic Z, Walkinshaw SA, Richmond DH. How to repair an anal sphincter injury after vaginal delivery: results of a randomised controlled trial. BJOG. 2006;113:201-207.

12. Fernando RJ, Sultan AH, Kettle C, Radley S, Jones P, O’Brien PMS. Repair techniques for obstetric anal sphincter injuries. A randomized controlled trial. Obstet Gynecol. 2006;107:1261-1268.

13. Fernando R, Sultan AH, Kettle C, Thakar R, Radley S. Methods of repair for obstetric anal sphincter injury. Cochrane Database Syst Rev. 2006;3:CD002866.-

14. Fernando RJ, Sultan AH, Radley S, Jones PW, Johanson RB. Management of obstetric anal sphincter injury: a systematic review and national practice survey. BMC Health Serv Res. 2002;2:9.-

15. MacArthur AJ, MacArthur C. Incidence, severity, and determinants of perineal pain after vaginal delivery: a prospective cohort study. Am J Obstet Gynecol. 2004;191:1199-1204.

16. Hedayati H, Parsons J, Crowther CA. Rectal analgesia for pain from perineal trauma following childbirth. Cochrane Database Syst Rev. 2003;(3):CD003931.-

17. Kettle C, Hills RK, Jones P, Darby L, Gray R, Johanson R. Continuous versus interrupted perineal repair with standard or rapidly absorbed sutures after spontaneous vaginal birth: a randomised controlled trial. Lancet. 2002;359:2217-2223.

18. Sultan AH, Monga AK, Kumar D, Stanton SL. Primary repair of obstetric anal sphincter rupture using the overlap technique. Br J Obstet Gynaecol. 1999;106:318-323.

19. Mahony R, Behan M, O’Herlihy C, O’Connell PR. Randomized, clinical trial of bowel confinement vs. laxative use after primary repair of a third-degree obstetric anal sphincter tear. Dis Colon Rectum. 2004;47:12-17.

20. Thakar R, Sultan A. Postpartum problems and the role of a perineal clinic. In: Sultan AH, Thakar R, Fenner DE, eds. Perineal and Anal Sphincter Trauma. London: Springer; 2007:65-79.

21. Williams A, Lavender T, Richmond DH, Tincello DG. Women’s experiences after a third-degree obstetric anal sphincter tear: a qualitative study. Birth. 2005;32:129-136.

22. Fynes M, Donnelly V, Behan M, O’Connell PR, O’Herlihy C. Effect of second vaginal delivery on anorectal physiology and faecal continence: a prospective study. Lancet. 1999;354:983-986.

23. Scheer I, Thakar R, Sultan A. Should women who sustained obstetric anal sphincter injuries be allowed a vaginal delivery? Neurourol Urodynam. 2006;25:512-513.

24. Peleg D, Kennedy CM, Merrill D, Zlatnik FJ. Risk of repetition of a severe perineal laceration. Obstet Gynecol. 1999;93:1021-1024.

25. Harkin R, Fitzpatrick M, O’Connell PR, O’Herlihy C. Anal sphincter disruption at vaginal delivery: is recurrence predictable? Eur J Obstet Gynaecol Reprod Biol. 2003;109:149-152.

26. Coats PM, Chan KK, Wilkins M, Beard RJ. A comparison between midline and mediolateral episiotomies. Br J Obstet Gynaecol. 1980;87:408-412.

27. Thakar R, Eason E. Prevention of perineal trauma. In: Sultan AH, Thakar R, Fenner DE, eds. Perineal and Anal Sphincter Trauma. London: Springer; 2007:52-64.

28. Johanson RB, Rice C, Doyle M. A randomised prospective study comparing the new vacuum extractor policy with forceps delivery. Br J Obstet Gynaecol. 1993;100:524-530.

29. Bofill JA, Rust OA, Schorr SJ, et al. A randomized prospective trial of the obstetric forceps versus the M-cup vacuum extractor. Am J Obstet Gynecol. 1996;175:1325-1330.

There is some evidence that repair of an isolated IAS defect benefits patients with established anal incontinence.

External anal sphincter. Because the EAS is normally under tonic contraction, it tends to retract when torn. Therefore, repair requires identification and grasping of the torn ends using Allis tissue forceps (FIGURE 6).

When the EAS is only partially torn (Grade 3a and some cases of Grade 3b), perform an end-to end repair using 2 or 3 mattress sutures, similar to repair of IAS injury, instead of hemostatic “figure of eight” sutures.

For a full-thickness tear (some cases of Grade 3b or 3c, or Grade 4), overlapping repair may be preferable in experienced hands. The EAS may need to be mobilized by dissecting it free of the ischioanal fat laterally using a pair of McIndoe scissors. The torn ends of the EAS can then be overlapped in “double-breasted” fashion (FIGURE 7) using PDS 3-0 sutures. Proper overlap is possible only when the full length of the torn ends is identified.

Overlapping the ends of the sphincter allows for greater surface area of contact between muscle. In contrast, end-to-end repair can be performed without identifying the full length of the EAS and may give rise to incomplete apposition. Fernando and colleagues demonstrated that, in experienced hands, early primary overlap repair carries a lower risk of fecal urgency and anal incontinence than does immediate primary end-to-end repair.^12,13

FIGURE 5 End-to-end repair

Internal anal sphincter (I) repair using mattress sutures, demonstrated on the latex Sultan model, used for training (www.perineum.net) (E, external sphincter; A, anal epithelium). SOURCE: Sultan AH, Thakar R² (used with permission).

FIGURE 6 Locating the external anal sphincter

The external sphincter (E), grasped with Allis forceps, is surrounded by the capsule (C) and lies medial to the ischioanal fat. SOURCE: Sultan AH, Thakar R² (used with permission).

FIGURE 7 Overlapping sphincter repair

Repair of a fourth degree tear (demonstrated on the Sultan model) using the overlap repair technique on the external sphincter (E). The anal epithelium (A) and the internal sphincter (I) have also been repaired. SOURCE: Sultan AH, Thakar R² (used with permission).

Perineal muscles

After repair of the sphincter, suture the perineal muscles to reconstruct the perineal body and provide support to the repaired anal sphincter. A short, deficient perineum would leave the anal sphincter more vulnerable to trauma during a subsequent vaginal delivery.

Next, suture the vaginal skin and approximate the perineal skin using Vicryl Rapide 2-0 subcuticular suture.

Examine, and document, the repair

Perform a rectal and vaginal examination to confirm adequate repair and ensure that no other tears have been missed—and that all tampons or swabs have been removed.

Make detailed notes of the findings and repair. A pro forma pictorial representation of the tears proves very useful when notes are reviewed following complications or during audit or litigation.

6. What does postoperative care entail?

Prophylactic antibiotics are common

No randomized trials have substantiated the benefits of intraoperative and postoperative antibiotics after repair of OASIS. Nevertheless, these drugs are commonly prescribed, especially after fourth- degree tears, because infection and wound breakdown could jeopardize the repair and lead to incontinence or fistula.^10,14

We prescribe intravenous broad-spectrum antibiotics such as cefuroxime and metronidazole intraoperatively and continue the drugs orally for 5 days.

Bladder catheterization is recommended

Severe perineal discomfort, especially after instrumental delivery, is a known cause of urinary retention. Moreover, after administration of regional anesthesia, it can take up to 12 hours before bladder sensation returns.

We recommend insertion of a Foley catheter for approximately 24 hours, unless medical staff can ensure that spontaneous voiding occurs at least every 3 to 4 hours without bladder overdistension.

Pain may persist after severe injury

The degree of pain following perineal trauma is related to the extent of the injury. OASIS is frequently associated with other more extensive injuries such as paravaginal tears. In one study, 91% of women continued to complain of severe perineal pain 7 days after OASIS.¹⁵

In a systematic review, Hedayati and associates found rectal analgesia, such as diclofenac sodium, to be effective at reducing pain from perineal trauma within the first 24 hours after birth; they also found that women used less additional analgesia within the first 48 hours after birth.¹⁶ Diclofenac is almost completely bound to protein, so excretion in breast milk is negligible.¹⁷

In women who have undergone repair of a fourth-degree tear, administer oral diclofenac; suppositories may be uncomfortable, and there is a theoretical risk of poor healing associated with local anti-inflammatory agents.