Wound dehiscence

Wound dehiscence is partial or complete separation of the edges of a closed surgical wound. In abdominal and sternal wounds, the deep layer (fascia or sternum) may separate, and bowel or mediastinal contents may protrude (evisceration). Fascial dehiscence is an emergency, while superficial dehiscence is usually managed locally.

Clinical relevance. Abdominal fascial dehiscence (burst abdomen) occurs in about 1 to 3% of laparotomies with mortality up to 15 to 20% in emergencies. Deep sternal wound complications occur in 1 to 3% of sternotomies and carry high mortality when mediastinitis develops. Dehiscence often follows infection and raised tension on the closure.

Mechanisms. Healing fails when tension on the repair exceeds wound strength (intra-abdominal pressure, cough, ileus, ascites, obesity), when tissue perfusion or healing biology is poor (malnutrition, diabetes, steroids, smoking, anaemia, uraemia, radiotherapy). Healing also fails when infection destroys sutures and tissue, or when closure technique is inadequate (suture length, tension, knots, wrong material). Classification.

• Superficial: skin and subcutaneous separation, fascia intact.
• Deep or fascial: separation of the fascia or sternal closure.
• Complete: evisceration of bowel, omentum or other organs, or exposure of heart or mediastinum.
• By tempo: early (under 48 hours, usually technical failure) and the usual window at 5 to 8 days after surgery; late in the second or third week with infection or malnutrition.

Key distinctions. Profuse serosanguineous (salmon pink) discharge from an abdominal wound in the first 10 days often precedes fascial dehiscence. A bulge or incisional hernia is a later complication of a healed but weak closure.

History.

• Operation, urgency, incision type, closure technique and suture material, and complications (contamination, infection, leak).
• Timing of onset, discharge (colour, volume), a sudden "pop" with coughing, vomiting, straining or lifting, and pain.
• Fever, wound redness, swelling, bowel function, vomiting, distension and nutrition.
• Risk factors: age over 65, obesity, diabetes, smoking, malnutrition (albumin under 30 g/L), corticosteroids or immunosuppression, chronic cough or chronic obstructive pulmonary disease, ascites, renal failure, cancer, radiotherapy, anaemia, anticoagulation and peripheral vascular disease.
• Sternotomy: sternal click, instability, drainage, fever and bypass grafting with bilateral internal mammary arteries.

Examination.

• Vital signs, hydration, signs of sepsis and nutritional state.
• Wound: remove the dressing, assess the extent of separation, depth, discharge, fascia visible or palpable gap, bowel or omentum visible, necrosis, and erythema.
• Abdomen: distension, tenderness, ileus, hernia, ascites and peritonism.
• Sternum: instability on coughing and compression, click, purulence, erythema, and chest wall pain.
• Pelvic and perineal wounds: faecal or urinary contamination, fistula.

Red flags.

• Visible bowel, omentum or other organ through the wound (evisceration).
• Fascial gap with serosanguineous drainage and a bulge on coughing.
• Sepsis (fever, tachycardia, hypotension, lactate over 2 mmol/L) or bilious or faecal drainage.
• Sternal instability with purulence, fever or bacteraemia (mediastinitis).
• Peritonitis or ileus.
• Dehiscence in a patient with a vascular graft or implant.

Special groups. Diabetes needs glucose control. Cirrhosis with ascites needs treatment of ascites. Obese patients have deep wounds with infected pockets. Children after major surgery need specialist care. Pregnant patients after caesarean section need review for infection and endometritis.

Types of separation.

• Superficial skin dehiscence with intact fascia.
• Deep fascial dehiscence, with or without evisceration.
• Sternal dehiscence with or without mediastinitis.
• Incisional hernia (fascial defect with intact skin).

Causes and contributors.

• Wound infection and surgical site infection, abscess, haematoma or seroma.
• Underlying leak or fistula (anastomotic leak, enterocutaneous fistula).
• Technical failure (suture break, knot slip, excessive tension, inadequate bites).
• Raised intra-abdominal pressure (ileus, obstruction, ascites, coughing, abdominal compartment syndrome).
• Impaired healing (malnutrition, diabetes, steroids, uraemia, smoking, radiotherapy, vitamin C deficiency, zinc deficiency, hypoalbuminaemia, anaemia).
• Chemotherapy, bevacizumab and other antiangiogenic agents, and immunosuppressants.
• Malignancy in the wound, pyoderma gangrenosum and vasculitis, factitious wound disruption.
• Necrotising infection and clostridial infection.

Similar presentations. Seroma or haematoma discharge, lymph leak, enteric fistula discharge, urinary leak, sinus tract with foreign body.

Step 1. Examine the wound and abdomen or sternum. A visible fascial defect with evisceration needs no investigation before surgery.

Step 2. First line tests: full blood count, CRP, urea, creatinine, electrolytes, albumin, glucose and HbA1c, lactate, coagulation, group and save, blood cultures for sepsis, and wound culture from deep tissue.

Step 3. Targeted tests.

• Ultrasound of the wound for collections and fascial gaps.
• CT of the abdomen with intravenous contrast for suspected leak, abscess, obstruction or ischaemia; CT chest for sternal infection and retrosternal collection.
• Chest radiograph and sternal imaging for wires and separation.
• Wound culture with Gram stain, and tissue for histology when non-infective causes are suspected.
• Nutrition assessment (albumin, prealbumin, weight loss, dietitian review) and vitamin levels.

Step 4. Assess operative risk and nutrition for re-closure.

Limitations. Superficial examination may miss deep fascial gaps in obese patients. Hypoalbuminaemia is a marker of illness rather than a direct measure of nutrition.

Evisceration or fascial dehiscence (emergency).

• Call the surgeon. Place the patient supine with knees flexed. Cover exposed bowel with sterile gauze soaked in warm saline, and cover with an impermeable dressing or a bowel bag. Do not push the bowel back or attempt to close the wound.
• Nil by mouth, large bore IV access, blood tests, group and crossmatch, isotonic crystalloid, and analgesia (morphine 1 to 2 mg IV every 5 minutes as needed, titrated to response and sedation).
• Antibiotics: cefazolin 2 g IV every 8 hours (maximum 6 g daily; for CrCl 10 to 34 mL/min give half the dose every 12 hours) plus metronidazole 500 mg IV every 8 hours (maximum 1.5 g daily).
• Alternatively, piperacillin with tazobactam 4.5 g IV every 6 hours (maximum 18 g piperacillin daily; every 8 hours for CrCl 20 to 40 mL/min; every 12 hours under 20 mL/min) when contamination, leak or hospital acquired infection is likely.
• Vancomycin 25 mg/kg IV (maximum 3 g) loading dose when MRSA is possible.
• Return to theatre for exploration, washout, repair of any leak, and re-closure with a mass closure technique (continuous slowly absorbable monofilament suture, suture to wound length ratio of 4 to 1, bites 1 cm from the edge and 1 cm apart).
• Temporary abdominal closure with negative pressure is used when closure is not possible, with later mesh or component repair. Use retention sutures or reinforcement only in selected patients.

Superficial dehiscence.

• Remove sutures or clips from infected areas, drain collections, irrigate and debride devitalised tissue.
• Dress with moist saline gauze twice daily or a hydrofibre or foam dressing, or use negative pressure wound therapy at continuous suction of 125 mmHg. Change the dressing every 48 to 72 hours, monitoring bleeding, exudate and wound bed.
• Avoid over exposed bowel, vessels, untreated osteomyelitis, necrotic tissue, malignancy in the wound and in patients on therapeutic anticoagulation without bleeding review.
• Allow healing by secondary intention, or delayed primary closure after infection clears.
• Antibiotics only for cellulitis, systemic signs, deep infection or high risk. Flucloxacillin 500 mg to 1 g orally every 6 hours for 5 to 7 days (maximum 4 g daily), or clindamycin 300 to 450 mg orally every 6 hours (maximum 1.8 g daily) if penicillin allergic.

Sternal dehiscence. Urgent cardiothoracic surgery review.

Broad spectrum antibiotics and surgery:

• Vancomycin 25 mg/kg IV loading dose (maximum 3 g) then maintenance dosed by kidney function and levels.
• Piperacillin with tazobactam 4.5 g IV every 6 hours (every 8 hours for CrCl 20 to 40 mL/min and every 12 hours under 20 mL/min).
• Alternatively, meropenem 1 g IV every 8 hours (1 g every 12 hours for CrCl 26 to 50 mL/min, 500 mg every 12 hours for CrCl 10 to 25 mL/min, 500 mg every 24 hours under 10 mL/min).
• Surgical debridement, sternal rewiring or plating, negative pressure therapy, and muscle or omental flap coverage.

Correct contributing factors.

• Glucose control to 6 to 10 mmol/L (insulin infusion in critical illness).
• Nutrition: dietitian review, energy 25 to 30 kcal/kg daily and protein 1.2 to 1.5 g/kg daily, enteral feeding preferred, and parenteral nutrition when the gut cannot be used for over 5 to 7 days. Correct anaemia, zinc or vitamin C deficiency when present.
• Treat cough and raised intra-abdominal pressure (bronchodilators, antitussives with care, decompress ileus, drain ascites), and stop smoking.
• Review corticosteroid and immunosuppressant dosing, and antiangiogenic drugs, with the prescriber.

Analgesia. Paracetamol 1 g orally or IV every 6 hours (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease). Avoid NSAIDs when bleeding or kidney injury is a risk. Use titrated opioids when severe, with a laxative.

Venous thromboembolism prophylaxis. Enoxaparin 40 mg subcutaneously once daily (20 mg daily if CrCl 15 to 30 mL/min; unfractionated heparin 5000 units subcutaneously every 8 to 12 hours if CrCl under 15 mL/min). Start when bleeding is controlled. Monitor platelets from day 4 and creatinine. Avoid when platelets are under 50 x 10^9/L or bleeding is active.

Monitoring. Daily wound review with measurement and photographs, temperature, CRP, white cell count, glucose, albumin, and nutrition review. Reassess the need for delayed closure at 5 to 7 days.

Monitor for fistula, bleeding, and sepsis.

Referral and escalation. Emergency surgery for fascial dehiscence. Cardiothoracic surgery for sternal infection. Plastic surgery for large defects and flaps. Tissue viability nurses, dietitians, diabetes team, and infectious diseases for deep infection.

Admission criteria. Fascial dehiscence or evisceration, sepsis, deep or sternal infection, suspected leak, inability to manage wounds at home, uncontrolled diabetes, or malnutrition.

Discharge and safety netting. Discharge superficial dehiscence when the patient is well, wound care is arranged (district or practice nurse, supplies), analgesia is controlled and follow up is booked at 3 to 7 days. Patients return for visible bowel, large bulge, increased discharge, bleeding, fever, redness, vomiting, abdominal distension or sternal instability. Advise avoiding heavy lifting for 6 weeks and splinting the wound when coughing.