Participants
Women having a history of a traumatic first delivery were first assessed for eligibility for anal ultrasonographic examination by the obstetrician at clinic visits in the third trimester of their second pregnancy. Women were eligible if they had a first vaginal instrumental delivery with forceps (vacuum extractions were not considered) and/or with a diagnosis of a third-degree perineal tear, had no self-reported anal incontinence at inclusion, were 18 years old or over, and signed informed consent to participate. The main exclusion criteria were a history of anal surgery, a fourth-degree perineal tear at the first delivery, self-reported AI, defined as involuntary leakage of gas or stools and any other indication for planned CS for non-proctologic reasons. After inclusion, women had a proctological evaluation including the Vaizey score 18 and anal endosonography with the same expert operator (LA).The Vaizey score was chosen for its sensitivity by accounting for 24 components of AI, including the loss of flatus with or without the loss of liquid and solid stool, pad use, stool urgency, medication use and quality of life. Endosonography was performed with an ultrasound scanner with a rotating rectal probe, a multifrequency of 7-10 MHz,and a hard sonolucent plastic cone (Bruel and Kjaer,Naemm, Denmark). Three anal canal levels (upper,middle, and lower) were studied and recorded (videorecorder, Sony, Tokyo, Japan). External anal sphincter lesions, as well as any internal sphincter lesions, were characterized as defined by Law et al. 19, according to defect angle and defined as severe if more than 90°. In case of anal sphincter lesions at endosonography, the patient was eligible for the randomized part of the trial.