Use of endoanal ultrasound for reducing the risk of complications related to anal sphincter injury after vaginal birth

Background During childbirth, many women sustain trauma to the perineum, which is the area between the vaginal opening and the anus. These tears can involve the perineal skin, the pelvic floor muscles, the external and internal anal sphincter muscles as well as the rectal mucosa (lining of the bowel). When these tears extend beyond the external anal sphincter they are called 'obstetric anal sphincter injuries' (OASIS). When women sustain an OASIS, they are at increased risk of developing anal incontinence either immediately following birth or later in life. Anal incontinence is associated with significant medical, hygiene and social problems. Endoanal ultrasound (EAUS) can be performed with a bedside scanner by inserting a small probe into the anus and the structures of the anal canal and perineum can be reviewed in real‐time. We proposed that by examining the perineum with EAUS after the birth of the baby and before the tear has been repaired, there would be an increase in detection of OASIS. This increased detection could lead to improved primary repair of the external and internal anal sphincter resulting in reduced rates of anal incontinence and improved quality of life for women. EAUS may also have a role after perineal repair in the evaluation of residual injury and may help guide a woman's management in subsequent pregnancies and allow for early referral to specialised units, minimising long‐term complications. Objectives To evaluate the effectiveness of EAUS in the detection of OASIS following vaginal birth and in reducing the risk of anal sphincter complications related to OASIS. Search methods We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 August 2015) and reference list of the one retrieved study. Selection criteria Randomised control trials (RCTs) comparing EAUS versus no ultrasound in women prior to repair of perineal trauma and EAUS performed after perineal repair. RCTs published in form only and trials using a cluster‐randomised design were eligible for inclusion, but none were identified. Trials using a cross‐over design and quasi‐RCTs were not eligible for inclusion. Data collection and analysis The two review authors independently assessed the single trial for inclusion and assessed trial quality. Both review authors independently extracted data. Data were checked for accuracy. Main results We included one trial that randomised 752 primiparous women with clinically detectable second‐degree perineal tears to