Obstetric anal sphincter injury: immediate repair and planning the next delivery

This is a third-degree tear, subtype 3a, because less than 50% of the external anal sphincter is torn; if the defect involves more than 50%, it is 3b, and if the internal sphincter is also torn, it is 3c. The reported 50% involvement makes it borderline between 3a and 3b, so examine carefully under good lighting and anaesthesia. Repair in theatre, not the delivery room. Good exposure, anaesthesia, muscle relaxation, and trained assistance improve outcomes. Use an end-to-end technique with 3-0 or 2-0 polyglactin (Vicryl) interrupted sutures for the external sphincter; an overlap technique is an option for full-thickness external sphincter tears but is not necessary for a partial 3a/3b injury. If the internal sphincter is torn, repair it separately with fine slowly absorbable sutures. Reconstruct the perineal muscles and skin without tension. Give broad-spectrum antibiotics, such as co-amoxiclav or cefazolin plus metronidazole, and a stool softener such as lactulose rather than a constipating agent. Avoid routine enemas and rectal NSAIDs. Document the classification, repair technique, sutures, and antibiotic plan. Arrange follow-up in a perineal clinic and warn her to report incontinence, wound breakdown, or fever.

Review at 6–12 weeks in a dedicated perineal clinic. Assess symptoms of anal incontinence, fecal urgency, and sexual function, and perform a digital anal examination. Endoanal ultrasound and anorectal manometry are useful if she is symptomatic or if the repair integrity is uncertain; some units offer them to all women after obstetric anal sphincter injury. Pelvic floor muscle training with a specialist physiotherapist should be offered. If symptoms persist after conservative treatment, refer to a colorectal surgeon for consideration of secondary sphincter repair, but do not rush to surgery before completing family planning. For future delivery, counsel her that vaginal birth carries a risk of recurrent sphincter injury and worsening continence, especially with instrumental delivery or a large baby. Elective caesarean section is recommended if she has persistent anal incontinence symptoms or abnormal endoanal ultrasound findings. If she is asymptomatic and investigations are normal, vaginal delivery can be offered with careful intrapartum management: avoid forceps, consider a controlled delivery, and have senior support. Document a shared decision. She should be reviewed early in the next pregnancy to plan mode of birth.

New flatus incontinence suggests persistent sphincter dysfunction and warrants urgent perineal clinic review. Assess symptom severity, stool consistency, and impact on quality of life; perform a digital rectal examination and arrange endoanal ultrasound and manometry if not already done. Start or reinforce pelvic floor muscle training and advise stool regulation to avoid constipation or loose stools. Refer to a colorectal surgeon for evaluation, but definitive secondary sphincter repair is usually deferred until after childbirth. Because she has symptoms and a previous third-degree tear, elective caesarean section should be recommended to avoid further sphincter trauma. Plan caesarean at 39 weeks, or earlier if obstetric indications arise, and document the discussion. If she declines caesarean, she should be counselled about the higher risk of worsening incontinence and recurrent injury; vaginal delivery would require senior obstetric presence, avoidance of instrumental delivery, and careful perineal support. In either mode, arrange neonatal and anaesthetic review, use thromboprophylaxis according to risk, and plan postpartum perineal follow-up. Discuss that caesarean does not guarantee continence, because pregnancy itself and ageing affect pelvic floor function.