Imaging characteristics of episiotomy scars on translabial ultrasound : an observational study

Introduction: Episiotomy has been purported to protect the anal sphincter from injury; efficacy is, however, disputed. Correct execution of episiotomy may have substantial implications. We aimed to describe the characteristics of episiotomy scars on translabial ultrasound (TLUS). Methods: In this retrospective observational study involving women after repair of obstetric anal sphincter injuries, 76 women with a history of episiotomy were analyzed. Episiotomy scars were assessed on tomographic ultrasound in the transverse plane using volumes acquired on pelvic floor muscle contraction. We measured scar length, depth, and angle relative to a vertical reference line. Episiotomy scars were described as 1) ipsilateral if they started on the same side as the direction of the episiotomy, 2) contralateral if on the opposite side, and 3) mediolateral if the scar began in the midline. Results: The mean scar angle was 50.5° (SD 14°; range 14.4°-79.3°) while mean scar length was 14.2 mm (SD 4.5; range 5.7-27.5 mm) and depth was 8.4 mm (SD 2.8, range 3.1-18.2 mm). Sixteen (21%) scars were located mediolateral while 32 (42%) were ipsilateral. In 28 (37%) women, the starting point of the episiotomy was located contralateral to the direction of the episiotomy. Conclusion: In this pilot series, the mean angle of episiotomy scars was within the safe zone of 40° to 60°, however, in one-third of cases the cut may have been initially directed toward the sphincter, not away from it. This observation suggests that not all episiotomies are performed optimally.