Prior 3rd and 4th Degree LACS
1. What every clinician should know
Initial visit
A woman who has experienced an anal sphincter injury with her previous delivery may come to you with questions about recurrence and which route of delivery is the best for her. She needs careful counseling regarding the management subsequent pregnancies. Most women’s concerns are related to the risk of recurrence of an anal sphincter tear and the risk of anal incontinence after another vaginal delivery.
You will want to inquire about the details of her last delivery; if she had an operative delivery, an episiotomy, shoulder dystocia or other risk factors for anal sphincter injuries (see chapter on 3rd and 4th degree lacerations).
Clinical incidence
The recurrence rate of an anal sphincter injury with a prior anal sphincter injury is 2-5 times higher than women with no prior laceration. Recurrence risk is even higher if the subsequent vaginal delivery is operative (OR 6.5%) or when a midline episiotomy is performed (OR 17.4%). If your patient has transient symptoms of fecal or flatal incontinence you can inform her that the risk of worsening of these symptoms can be up to 24%. Although women with lacerations report increased incontinence compared to women without any sphincter trauma, both groups have an increased risk of incontinence with subsequent deliveries. Prior fourth-degree lacerations are associated with severe anal incontinence more than with prior third-degree lacerations.
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2. Diagnosis and differential diagnosis
Inquire about anal function: asymptomatic and symptomatic
You will want to ask your patient questions about her anal function and the degree of flatal or fecal incontinence she may or may not be experiencing. You will also want to ask her whether these symptoms have improved over time or have remained the same. We suggest using questionnaires, as compromised anal function, no matter how minimal, can be an embarrassing subject to broach.
Asymptomatic women who have little to no compromise of their anal function should be allowed to have a vaginal delivery and should be counseled that they have a 95% chance of NOT experiencing a recurrent anal sphincter injury or developing de novo anal incontinence following delivery. If she has risk factors for a traumatic delivery you may want to recommend a cesarean section (CS).
Symptomatic women who have adequately controlled their symptoms with conservative measures should be offered a CS to minimize the risk of worsening anal function. Women who already have decreased anal function and are symptomatic may not be further affected and may be counseled to have either a vaginal delivery or CS with subsequent secondary surgical repair of the anal sphincter after delivery. Any woman who has had successful reconstructive sphincter surgery should be strongly advised to delivery by CS.
Endoanal ultrasound can be used to assess the integrity of the sphincter, but should ideally be performed by a urogynecologist, as sonographic anatomy of the perineum is complex and accurate assessment requires formal training.
3. Management
Advice about route of delivery
Your patient may request an elective cesarean section after a prior anal sphincter tear. If your patient is asymptomatic you may suggest an elective cesarean section to avoid new onset or worsening of symptoms with a vaginal delivery. If your patient has already had a secondary surgical repair of a prior anal sphincter injury, cesarean section is recommended. Extensive counseling on the morbidity and mortality associated with cesarean section versus vaginal delivery is recommended, as is counseling on the need for subsequent cesarean sections. If your patient is symptomatic and will have a sphincteroplasty in the future, a vaginal delivery may be a good option as her anal function can be restored secondarily.
If fecal incontinence is severe and is not managed well by conservative measures (changes in diet, biofeedback, constipating agents), you should refer your patient to a specialist for more definitive treatment.
6. What is the evidence for specific management and treatment recommendations
Payne, TN, Carey, JN, Rayburn, WF. “Prior third or fourth-degree perineal tears and recurrence risks”. International J of Obstet Gynecol. vol. 64. 1999. pp. 55-7.
Fenner, D. “Anal Incontinence: Relationship to pregnancy, vaginal delivery, and Cesarean Section”. Seminars in Perinat. vol. 30. 2006. pp. 261-6.
Tetzchner, T, Sorensen, M, Lose, G, Christiensen, J. “Anal and urinary incontinence in women with obstetric anal sphincter rupture”. BJOG. vol. 103. 1996. pp. 1034-40.
Sultan, AH, Thakar, R, Fenner, DE. “Perineal and Anal Sphincter Trauma: Diagnosis and Clinical Management”. 2007.
Sangalli, MR, Floris, L, Faltin, D. “Anal incontinence in women with third or fourth degree perineal tears and subsequent vaginal deliveries”. Aust N Z J Obstet Gynecol. vol. 40. 2000. pp. 244-8.
Sultan, AH, Thakar, R. “Lower genital tract and anal sphincter trauma”. Best Pract Res Clin Obstet Gynecol. vol. 16. 2002. pp. 99-115.
McKenna, DS, Ester, JB, Fischer, MD. “Elective Cesarean Section for women with a previous anal sphincter rupture”. Am J Obstet Gynecol. vol. 189. 2003. pp. 1251-60.
Krebs, L, Langhoff-Roos, J. “Elective Cesarean Section for Term Breech”. Obstet Gynecol. vol. 101. 2003. pp. 690-6.
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