What is the proper management and repair of a 4th degree perineal tear?

Repair of Fourth-Degree Perineal Tear

Fourth-degree perineal tears require immediate surgical repair in the operating room under regional or general anesthesia, with sequential closure from deep to superficial structures: anorectal mucosa, internal anal sphincter, external anal sphincter, rectovaginal fascia, perineal body, perineal skin, and vaginal tissues. 1

Preoperative Preparation

Environment and Anesthesia:

• Regional or general anesthesia is mandatory for adequate pain control and muscle relaxation 1
• Repair in the operating room with proper lighting, visualization, and exposure 1
• Place Foley catheter before initiating repair 1
• Count all surgical instruments, sponges, and sutures pre- and postoperatively 1

Infection Prevention:

• Perform vaginal preparation with povidone-iodine (or chlorhexidine if iodine-allergic) 1
• Administer prophylactic antibiotics before repair—this reduces wound complications from 24.1% to 8.2% 1
• Use second- or third-generation cephalosporin (cefoxitin 2g or cefotetan 1g IV), or metronidazole 500mg with gentamicin 5mg/kg for penicillin-allergic patients 1

Surgical Repair Technique (Deep to Superficial)

Step 1: Anorectal Mucosa

• Close with interrupted or continuous non-locked 3-0 or 4-0 delayed absorbable sutures (polyglactin or poliglecaprone) 1
• Non-locking technique prevents excessive tension that causes tissue edema and necrosis 1

Step 2: Internal Anal Sphincter (IAS)

• Identify the IAS first—it is thin, pale pink, and lies adjacent to the anorectal mucosa 1
• Grasp torn external anal sphincter (EAS) ends with Allis clamps and bring to midline; the IAS extends 1.2 cm cephalad from the proximal EAS margin 1
• Repair using end-to-end technique with mattress or interrupted 3-0 delayed absorbable sutures 1
• IAS repair improves 1-year anal incontinence rates 1

Step 3: External Anal Sphincter (EAS)

• Use overlapping technique rather than end-to-end—overlapping repair reduces fecal urgency and lowers anal incontinence scores at 1 year 1
• While both techniques show similar rates of perineal pain and dyspareunia, overlapping provides superior functional outcomes 1
• Use 3-0 delayed absorbable suture 1

Step 4: Rectovaginal Fascia and Perineal Body

• Reapproximate using continuous non-locking absorbable sutures 1
• Reapproximate bulbocavernosus and transverse perineal muscles in running, continuous fashion 1

Step 5: Perineal Skin

• Use continuous non-locking subcuticular sutures to avoid nerve ending damage 1
• Consider leaving skin unsutured or using skin adhesive to reduce pain and dyspareunia 1, 2

Step 6: Vaginal Muscularis and Epithelium

• Close with continuous non-locking suture from apex to hymenal ring 1

Postoperative Management

Immediate Care:

• Monitor until complete recovery from anesthesia 1
• Keep Foley catheter in place; perform voiding trial on postoperative day 1 1
• Document laceration type and repair technique comprehensively 1, 2

Pain Control:

• Acetaminophen and ibuprofen as first-line agents 1, 2
• Ice packs applied to perineum 1, 2
• Avoid opiates unless absolutely necessary 1, 2

Wound Care:

• Sitz baths twice daily until first wound check 1, 2

Bowel Management:

• Prescribe stool softeners (polyethylene glycol 4450 or mineral oil) twice daily for 6 weeks postpartum to achieve toothpaste consistency stools 1, 2
• This prevents straining that could compromise healing 2

Follow-up:

• Schedule early follow-up within 2 weeks, ideally in specialized postpartum perineal clinic 1, 2
• Educate patient on degree of injury and importance of close follow-up 1, 2
• If concern for anal sphincter compromise, perform endoanal ultrasound to assess full extent of damage 1, 2

Critical Pitfalls to Avoid

• Failure to identify and repair the IAS separately—this is the most common technical error and leads to persistent anal incontinence 1
• Using locked sutures creates excessive tension causing tissue necrosis 1
• Inadequate bowel management postoperatively leads to constipation and wound disruption 2
• Omitting prophylactic antibiotics increases wound infection risk by 300% 1
• Repairing in labor suite without adequate lighting and exposure compromises visualization 1