Classification and Management of Obstetric Perineal Injury

Diagnostic Approach and Management

The American College of Obstetricians and Gynecologists (ACOG) recommends a systematic evaluation including visual inspection, thorough perineal examination, and mandatory digital rectal examination to detect OASIS, as up to 35% of anal sphincter injuries are missed without rectal examination 2, 1
Ensure adequate lighting and proper patient positioning before examination, as inadequate lighting can cause misclassification of injury severity 1
Inform the patient of the need and reasoning for examination, and perform digital rectal examination on all patients to improve OASIS detection rates 2, 1

For hemostatic first-degree tears, use skin adhesive or no suturing rather than traditional suturing, as this reduces pain and procedure time with equivalent functional outcomes, as recommended by the American College of Obstetricians and Gynecologists (ACOG) 1
For second-degree tears, if hemostatic, use skin adhesive or no suturing for the perineal skin after repairing deeper layers, as this reduces pain, dyspareunia, and improves breastfeeding rates at 3 months 1
For third- and fourth-degree tears (OASIS), the Society of Obstetricians and Gynaecologists of Canada and the Royal College of Obstetricians and Gynaecologists (RCOG) recommend repair sequentially from deep to superficial structures, using end-to-end technique with either mattress or interrupted sutures using 3-0 delayed absorbable suture for the internal anal sphincter (IAS) 3

Post-operative care includes stool softeners, pain control, sitz baths, early follow-up, and patient education to achieve optimal outcomes, as recommended by the American College of Obstetricians and Gynecologists (ACOG) 1
Maintain Foley catheter until postoperative day 1, then perform voiding trial to ensure adequate bladder function, and prescribe stool softeners to achieve soft stools and prevent strain 3, 1

The baseline risk of wound complications after OASIS repair is high, with infection rates of 19.8% and dehiscence rates of 24.6%, leading to worsened physical, emotional, and sexual satisfaction persisting up to 9 months postpartum, according to the American Journal of Obstetrics and Gynecology 2, 4
Overall infection rates after perineal trauma range from 0.1% to 23.6%, and overall dehiscence rates range from 0.21% to 24.6%, with risk increasing with missed diagnosis, inappropriate repair technique, and lack of surgeon experience 2
OASIS is associated with 29-53% flatal incontinence and 5-10% fecal incontinence in the first 6 months postpartum, causing embarrassment, social isolation, and affecting quality of life 2, 4