Obstetric anal sphincter injury: incidence, risk factors, and management.
OBJECTIVE
Obstetric sphincter damage is the most common cause of fecal incontinence in women. This review aimed to survey the literature, and reach a consensus, on its incidence, risk factors, and management.


METHODS
This systematic review identified relevant studies from the following sources: Medline, Cochrane database, cross referencing from identified articles, conference abstracts and proceedings, and guidelines published by the National Institute of Clinical Excellence (United Kingdom), Royal College of Obstetricians and Gynaecologists (United Kingdom), and American College of Obstetricians and Gynecologists.


RESULTS
A total of 451 articles and abstracts were reviewed. There was a wide variation in the reported incidence of anal sphincter muscle injury from childbirth, with the true incidence likely to be approximately 11% of postpartum women. Risk factors for injury included instrumental delivery, prolonged second stage of labor, birth weight greater than 4 kg, fetal occipitoposterior presentation, and episiotomy. First vaginal delivery, induction of labor, epidural anesthesia, early pushing, and active restraint of the fetal head during delivery may be associated with an increased risk of sphincter trauma. The majority of sphincter tears can be identified clinically by a suitably trained clinician. In those with recognized tears at the time of delivery repair should be performed using long-term absorbable sutures. Patients presenting later with fecal incontinence may be managed successfully using antidiarrheal drugs and biofeedback. In those who fail conservative treatment, and who have a substantial sphincter disruption, elective repair may be attempted. The results of primary and elective repair may deteriorate with time. Sacral nerve stimulation may be an appropriate alternative treatment modality.


CONCLUSIONS
Obstetric anal sphincter damage, and related fecal incontinence, are common. Risk factors for such trauma are well recognized, and should allow for reduction of injury by proactive management. Improved classification, recognition, and follow-up of at-risk patients should facilitate improved outcome. Further studies are required to determine optimal long-term management.
Dudding
Thomas C
TC
Physiology Unit, St. Mark's Hospital, London.
Vaizey
Carolynne J
CJ
Kamm
Michael A
MA
D001003:Anal Canal / Q000293:injuries*; D000928:Antidepressive Agents / Q000627:therapeutic use; D032763:Behavior Control / Q000379:methods; D002585:Cesarean Section; D004841:Episiotomy; D005242:Fecal Incontinence / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D005260:Female; D006801:Humans; D015994:Incidence; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D011247:Pregnancy; D011379:Prognosis; D019651:Plastic Surgery Procedures / Q000379:methods; D012307:Risk Factors
D000928:Antidepressive Agents