Applied Evidence

Obstetric anal sphincter injury: How to avoid, how to repair: A literature review

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Long-term management

Ask patients about incontinence

Given that some women are too embarrassed to seek assistance, ask those with obstetric anal sphincter injury specific questions about any symptoms of anal incontinence at a follow-up visit, such as the 6-week postpartum visit (SOR: C).37,40 In some practices, all women who have sustained a third- or fourth-degree laceration are routinely scheduled for a 3-month follow-up visit to a dedicated clinic, irrespective of symptoms. Given the prevalence of occult obstetric anal sphincter injury for primigravid women, you may find it best to survey all women postnatally concerning any changes in anal continence. TABLE 3 demonstrates a validated, modified patient survey of anal incontinence.37,40 A score of 6 is often used as a cutoff.

Fecal Continence Scoring scale

1. Passage of any flatus when socially undesirable
2. Any incontinence of liquid stool
3. Any need to wear a pad because of anal symptoms
4. Any incontinence of solid stool
5. Any fecal urgency (inability to defer defecation for more than 5 minutes)
0 Never
1 Rarely (<1/month)
2 Sometimes (1/week–1/month
3 Usually (1/day–1/week)
4 Always (>1/day)
A score of 0 implies complete continence and a score of 20 complete incontinence.
A score of 6 has been suggested as a cut-off to determine need for evaluation.
Source: Mahony et al, 2001;43 modified from Jorge and Wexner, 1993.44

When additional evaluation is needed

Patients who have symptoms of altered continence at 3 months (or who score above 6 on the Wexner scale) should be seen at a dedicated gynecologic or colorectal surgery clinic,46 where they can receive a more detailed clinical evaluation and undergo anal manometry (during resting and forced squeezing) or endoanal ultrasonography. Some patients respond well to physical therapy, though a few patients ultimately require reconstructive colorectal surgery and temporary colostomy.

Management in a subsequent pregnancy

Women who have had an obstetric anal sphincter injury are at increased risk for repeat injury in a future pregnancy.48 At some units, all such women are routinely offered a prenatal visit at the end of the second trimester to review their symptoms and to evaluate the anal sphincter with manometry or ultrasound. A large prospective study, however, found that recurrence of obstetric anal sphincter injury could not be predicted and that 95% of women with prior injury did not sustain further overt sphincter damage during a subsequent vaginal delivery.49

However, for some women, a repeat anal sphincter laceration could prove devastating. For these women—eg, those with previous severe symptoms that required secondary surgical repair—initiate an in-depth discussion concerning the risks and benefits of elective cesarean delivery versus vaginal delivery.37,40

New definitions and prevalence of incontinence

Historically, fecal incontinence was defined as “the involuntary or inappropriate passage of feces.”10 However, a preferred definition now refers instead to anal incontinence, which is “any involuntary loss of feces or flatus, or urge incontinence, that is adversely affecting a woman’s quality of life.”40 This definition includes urgency of defecation and incontinence of flatus, both of which are much more common symptoms than fecal incontinence.50

Data are lacking on the community prevalence of incontinence, although it is known that women of age 45 experience 8 times the incidence of incontinence as men of the same age and that it increases in prevalence with age.10 A Canadian survey of almost 1000 women at 3 months postpartum revealed that 3.1% admitted to incontinence of feces while 25% admitted to involuntary escape of flatus. The subgroup of women who suffered clinical anal sphincter injury (that is, third- or fourth-degree lacerations) had considerably increased rates of incontinence of feces (7.8%) and of flatus (48%).24 It has been reported that approximately half of women who sustained anal sphincter tears in labor complained of anal, urinary, or perineal symptoms at a mean follow-up of 2.6 years after the injury.51 Most studies agree that many women are embarrassed about symptoms of anal incontinence and are reluctant to self-report them.50

David Power, MD, MPH, Department of Family Medicine and Community Health, University of Minnesota, Mayo Mail Code 381, 516 Delaware St SE, Minneapolis, MN 55455. E-mail: [email protected]


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