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Am Fam Physician. 2000;61(11):3437-3440

The most common cause of fecal incontinence is related to obstetric vaginal deliveries and disruption of the anal sphincter complex. Lacerations of the anal sphincter occur in 0.6 to 5 percent of vaginal deliveries. This rate is increased to 50 percent if they occur in association with midline episiotomy and forceps delivery. It is estimated that 40 percent of women with anal sphincter lacerations have subsequent anorectal dysfunction including significant fecal incontinence. It has been thought that primary repair of the obstetric laceration would prevent adverse sequelae, although there is little evidence to support this. Kammerer-Doak and associates prospectively assessed the integrity of the anal sphincter in women with and without obstetric anal sphincter lacerations using transvaginal ultrasonography to identify occult lacerations.

Fifteen women who sustained obstetric anal sphincter lacerations (third- and fourth-degree lacerations) at the time of vaginal delivery were matched with 15 control subjects. Primary repair of the internal sphincter and rectal mucosa was performed with a running layer of 3-0 polyglactin 910 suture. The external anal sphincter was repaired with four interrupted 1-0 Vicryl sutures with an end-to-end technique. Women underwent physical and transvaginal ultrasonographic evaluations at six weeks and four months postpartum and were queried regarding anorectal symptoms.

At the six-week postpartum visit, 40 percent of the women with a history of obstetric laceration were noted to have a separated sphincter on physical examination compared with none of the women in the control group. Median anal resting and squeeze tones were significantly less in the laceration group. At the same visit, ultrasonography of women with a laceration history and of control subjects revealed a disrupted external anal sphincter in 40 and 20 percent, respectively, and a disrupted internal anal sphincter in 47 and 7 percent, respectively.

An 86 percent correlation was noted between physical examination findings of a separated sphincter and ultrasonographic evidence of a disrupted external anal sphincter. The subjective assessment of fecal incontinence symptoms was significantly greater among women who had sustained obstetric lacerations than among control subjects (26 versus 2 percent). The fecal incontinence score was significantly greater in the laceration group. Overall, the fecal incontinence score was associated with a disrupted internal anal sphincter but not with disruption of the external anal sphincter, as determined by ultrasonography.

At the four-month postpartum visit, women with a history of obstetric laceration were noted to have significantly more separated anal sphincters and decreased resting and squeeze tones on physical examination, a disrupted internal anal sphincter on ultrasonography and increased fecal incontinence scores with respect to the control group. Comparisons between the six-week and the four-month postpartum visits revealed complete resolution of fecal incontinence symptoms in 36 percent of subjects. The presence of anorectal dysfunction was reported in 43 percent of women in the laceration group versus 8 percent of control subjects at four months. In addition, the median fecal incontinence scores continued to be significantly greater in the laceration group.

Results of this study demonstrate that anorectal dysfunction was present at the six-week and four-month postpartum visits in women who had obstetric and sphincteric rupture and had undergone primary surgical repair following vaginal delivery. The fact that the symptoms of fecal incontinence did not diminish for 43 percent of the women in the laceration group indicates lack of resolution of damage despite primary repair at the time of delivery.

The authors conclude that current surgical techniques for the repair of obstetric anal sphincter lacerations may be less than optimal. Ultrasonographic examinations revealed a separated anal sphincter in 40 percent of the women with obstetric laceration, despite primary repair at the time of delivery.

editor's note: Although the participant numbers were small, this is a well-designed study. Editorial discussion following the article stressed the key take-home points of this study. Careful questioning of the woman at the first postpartum visit about symptoms of fecal incontinence is important. A careful physical examination of anorectal tone may help to determine which women will benefit from sphincteroplasty. Transvaginal ultrasonography can be used to detect occult sphincter disruptions that may affect quality of life. Limiting the use of episiotomies will help avoid the long-term sequela of fecal incontinence.—b.a.

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