Abdominal Wall Dehiscence

Abdominal wall dehiscence (fascial dehiscence, burst abdomen) is the partial or complete separation of the fascial layer of a laparotomy closure, allowing abdominal contents to push through the wound.

Evisceration is the extrusion of bowel or omentum through the skin as well. Incidence after midline laparotomy is 1 to 3% (up to 10 to 15% in high risk emergency surgery).

Mortality in complete dehiscence with evisceration is 10 to 45%, mostly from the underlying disease and sepsis.

It most often becomes apparent between day 5 and day 10 after surgery, but may occur earlier or later.

Failure of the fascial closure is a mechanical problem with a biological contribution: sutures cut through fascia that has lost strength because of infection, ischaemia, malnutrition or poor healing, while raised intra abdominal pressure pulls the closure apart.

Risk factors:

• Patient: age above 65, male sex, obesity, malnutrition (low albumin below 30 g/L), anaemia, diabetes, smoking, chronic cough or COPD, steroid or immunosuppressive use, chemotherapy or bevacizumab, uraemia, jaundice, malignancy, connective tissue disease, previous laparotomy

• Operative: emergency surgery, contamination, long operation time, midline incision, poor suture technique (large tissue bites, too tight, too few), suture material too fine or short lived, wound infection, intraoperative hypotension

• Postoperative: ileus and distension, abdominal compartment syndrome, coughing, vomiting, straining, early heavy lifting, SSI, haematoma, seroma

Prevention is central.

Evidence based closure technique is the small bites technique: a continuous monofilament slowly absorbable suture (for example PDS 2-0 or looped PDS 1) placed 5 mm from the fascial edge and 5 mm apart, with a suture-to-wound length ratio of at least 4:1, closing with no undue tension.

Prophylactic onlay or retrorectus mesh reinforcement in high risk patients reduces incisional hernia and may reduce dehiscence.

• Early warning: copious serosanguinous ("salmon pink") fluid leaking from the wound on postoperative days 4 to 8, in about 25 to 50% of patients who later dehisce. This sign needs prompt examination of the wound, because the fascia is likely to be failing even if the skin is intact.

• Other features: sudden "pop" or tearing sensation after coughing, straining or vomiting; a bulge or palpable fascial gap on pressing the wound; prominent wound edges; and a feeling that the wound is giving way. Superficial signs of infection (erythema, warmth, purulent discharge) are present in many.

• Complete dehiscence with evisceration: bowel loops or omentum are visible through the open wound. The patient may be distressed, with abdominal pain, tachycardia and signs of peritoneal contamination or underlying sepsis, and there is a risk of bowel strangulation, drying, ischaemia and perforation.

• Dehiscence needs an immediate search for a cause. Look for an anastomotic leak, abscess, bowel obstruction, abdominal compartment syndrome, coagulopathy, or poor technique. Late complications include incisional hernia in up to 60 to 70% of those who heal by secondary intention.

• Diagnosis is clinical. Inspect the wound, ask the patient to cough, and gently probe through any gap, taking care not to injure bowel. If the skin is closed and discharge is seen, open the wound sufficiently to see the fascia.

• Investigations to identify the cause and fitness for surgery: full blood count, C-reactive protein, urea and electrolytes, albumin, coagulation, blood glucose, lactate, group and save, and blood cultures if febrile.

• CT with contrast is indicated if a leak, collection or obstruction is suspected, provided the patient is stable.

• Measure intra abdominal pressure via the bladder where ileus or distension is present.

Evisceration (emergency).

Place the patient supine with knees flexed to reduce abdominal tension. Cover the exposed bowel with moist (warm sterile saline) gauze or a sterile plastic drape. Do not try to push the viscera back, and do not leave them exposed and dry

Keep the patient nil by mouth; insert a nasogastric tube if there is vomiting or ileus. Obtain IV access, start crystalloid resuscitation, send blood tests, and begin broad spectrum antibiotics (piperacillin tazobactam 4.5 g IV every 6 to 8 hours or ceftriaxone 2 g daily with metronidazole 500 mg every 8 hours)

Analgesia AND Arrange urgent return to theatre

Surgical re-closure.

Under general anaesthesia, remove old sutures, inspect the whole abdomen, treat the cause (washout, repair of leak, drainage), assess bowel viability, and close the fascia with a mass closure technique when tension allows. Use a monofilament slowly absorbable or non-absorbable suture (for example PDS or nylon number 1 loop), small bites, 4:1 ratio.

Retention sutures (through-all-layers, tied over bolsters) are an option in the highest risk, infected or malnourished patients, but they are painful and cause skin problems. If tension is excessive, consider mesh bridging (in clean fields: absorbable or biologic in contaminated), component separation, or temporary abdominal closure with negative pressure and fascial traction.

In an infected field, leave the skin open and consider delayed closure.

Partial dehiscence without evisceration and without sepsis.

Selected, stable, frail patients may be managed non-operatively with an abdominal binder, wound dressings and negative pressure wound therapy, accepting a planned incisional hernia and later repair.

Operative repair is preferred in fit patients.

Perioperative optimisation. Nutrition (enteral feeding; protein target 1.5 g/kg/day), control of cough and constipation, glycaemic control, smoking cessation, treatment of infection, avoidance of straining, and abdominal binder for support.

Delay heavy lifting for 6 to 8 weeks.

Physiotherapy advice about splinting the wound when coughing.

Follow up. Monitor wound healing and for incisional hernia. Elective hernia repair is delayed for at least 6 to 12 months after a healed infected wound, with preoperative optimisation of weight, smoking and glycaemia.