Importance of evacuatory disturbance in evaluation of faecal incontinence after third degree obstetric tear

Objective  To correlate anorectal function including rectal evacuation with anorectal physiology and endoanal ultrasound in women with third degree obstetric anal sphincter injury repaired at the time of delivery. Patients and methods  Forty-four women with repaired third degree tears underwent anorectal physiology, anal ultrasonography and clinical assessment using the St. Marks incontinence score (0–24). Evacuatory disturbance was assessed by questionnaire. Results  There was a significant correlation between disturbed evacuation and incontinence symptoms (P =0.030). There was also a significant correlation between disturbed evacuation and internal anal sphincter (IAS) injury (P = 0.026), but there was no correlation with external anal sphincter (EAS) injury. There was a correlation between disturbed evacuation and low resting anal pressure (P = 0.013). Although IAS defects were associated with low anal pressure, only the correlation with Maximum Squeeze Pressure reached statistical significance (P = 0.018). Conclusion  Women with evacuatory disturbance after repaired third degree tears have a greater level of incontinence than those whose emptying is normal. This association is related to internal sphincter injury and reduced anal sphincter pressures.