Perforated Appendicitis

Perforated appendicitis is full thickness disruption of the appendiceal wall with contamination of the surrounding tissues or peritoneal cavity.

The clinical spectrum ranges from a small contained perforation with phlegmon or abscess to diffuse purulent or faeculent peritonitis with septic shock.

Perforated appendicitis is a complicated intra abdominal infection. Management requires both antimicrobial therapy and source control unless the perforation is well contained and deliberately managed nonoperatively in a selected stable patient.

The patient commonly has a longer symptom duration than uncomplicated appendicitis.

Typical findings include:

• Increasing right lower quadrant pain or pain becoming diffuse
• Fever and persistent tachycardia
• Local or generalised guarding
• Abdominal distension and ileus
• Vomiting and inability to tolerate oral intake

A contained perforation may produce a localised mass or abscess without dramatic generalised signs.

Diffuse perforation may present with rigidity, severe sepsis, hypotension, oliguria, altered mentation, metabolic acidosis and elevated lactate.

An apparent transient reduction in pain does not exclude perforation. Decompression of an obstructed inflamed appendix can briefly alter pain before contamination produces worsening peritonitis.

In a stable adult, contrast enhanced CT is the most useful study.

Features supporting perforation include:

• Focal appendiceal wall defect
• Extraluminal gas
• Extraluminal appendicolith
• Periappendiceal abscess
• Phlegmon
• Significant free fluid
• Reduced mural enhancement suggesting necrosis

Absence of obvious extraluminal gas does not exclude microscopic or contained perforation.

Check full blood count, C reactive protein, renal function, electrolytes, liver profile when appropriate, coagulation profile and blood group. Measure lactate and blood gas in systemic illness.

In septic patients, blood cultures should ideally be obtained before antibiotics if this does not delay treatment. During operative or percutaneous source control, obtain intra abdominal cultures.

Do not delay source control to obtain CT in a deteriorating patient with convincing generalised peritonitis and a clear surgical abdomen.

The first distinction is contained perforation versus uncontrolled contamination.

• A stable contained perforation with abscess or phlegmon may be treated according to the appendicular abscess or mass pathway.

• Diffuse peritonitis, worsening sepsis or physiological instability requires urgent operative source control.

• Provide balanced crystalloid for hypovolaemia, correct major electrolyte disturbance, establish adequate IV access and treat pain. In septic shock, fluid and vasopressor resuscitation should proceed while theatre preparation is underway. Source control should not wait for complete physiological normalisation.

• Start antibiotics immediately.

For community acquired complicated appendicitis: Ceftriaxone 2 g IV every 24 hours plus metronidazole 500 mg IV or orally every 12 hours. For severe sepsis, healthcare associated infection or substantial resistant organism risk: Piperacillin tazobactam 4.5 g IV loading dose followed by 4.5 g IV every 8 hours as an extended infusion. Renal dose adjustment is required when renal function is significantly impaired.

• Laparoscopic appendicectomy is preferred when the patient can tolerate laparoscopy and expertise is available. The goals are removal of the septic focus, evacuation of gross pus or faeculent material and assessment of the appendiceal base and adjacent bowel.

If the caecal base is viable, secure stump closure is sufficient. Severe necrosis extending into the caecum may require stapled partial caecectomy or ileocaecal resection. The extent of resection should be dictated by tissue viability rather than the presence of perforation alone.

Routine aggressive peritoneal lavage is unnecessary. Adequate aspiration and removal of gross contamination are generally sufficient. Routine drains after appendicectomy for complicated appendicitis are also not recommended.

• After adequate source control, antimicrobial therapy should generally be stopped after approximately 4 days, assuming the patient is improving. Surgical Infection Society guidance recommends no more than 96 hours after adequate source contro

Do not prolong antibiotics simply because the original appendix was perforated.

Persistent fever, tachycardia, worsening abdominal pain, failure of bowel function to recover or recurrent sepsis should trigger evaluation for:

• Residual intra abdominal abscess

• Inadequate source control

• Stump failure

• Bowel injury

• New postoperative infection

CT with IV contrast is usually the next investigation in a stable postoperative adult.