Postoperative Intra Abdominal Collection

A postoperative intra abdominal collection is accumulation of fluid within the abdominal or pelvic cavity after surgery. It may represent sterile seroma, haematoma, bile, pancreatic fluid, urine, lymph, enteric content or infected abscess.

The important clinical task is determining whether the collection is infected and whether an ongoing source such as an anastomotic leak, bowel injury or bile leak persists.

Small sterile collections may be asymptomatic.

Clinically important infected collections often present with:

• Persistent or recurrent fever
• Unexplained tachycardia
• Local abdominal or pelvic pain
• Failure of postoperative ileus to resolve
• Rising inflammatory markers
• Poor oral tolerance
• New organ dysfunction

A patient who initially improves then develops fever and tachycardia several days after abdominal surgery should be considered to have an intra abdominal complication until excluded.

CT abdomen and pelvis with IV contrast: defines the collection and determines whether image guided drainage is feasible; simultaneously assess for anastomotic leak or another continuing source.

Laboratory studies assess physiological effect rather than prove infection.

When drainage is performed, send fluid for bacterial culture to permit antimicrobial narrowing. Current IDSA guidance supports obtaining intra abdominal cultures during source control for complicated infection.

Not every postoperative fluid collection needs treatment.

Observe a small clinically silent sterile appearing collection when there is no evidence of infection or ongoing leak.

A mature accessible collection associated with persistent infection should undergo image guided percutaneous drainage whenever this can provide definitive source control.

Start antibiotics when infection is clinically suspected.

A reasonable regimen for lower risk postoperative infection is:

Ceftriaxone 2 g IV every 24 hours plus metronidazole 500 mg IV every 12 hours.

Healthcare associated infection, septic shock or substantial resistant organism risk generally warrants broader treatment such as:

Piperacillin tazobactam 4.5 g IV every 8 hours by extended infusion, adjusted for renal function.

Surgical exploration is required when:

• Generalised peritonitis is present
• Percutaneous drainage cannot control infection
• An ongoing bowel or anastomotic leak requires repair or diversion
• Bowel ischaemia or necrosis is suspected
• The patient deteriorates despite drainage

After adequate source control, limit antibiotics to approximately 4 days.

Persistent fever after drainage should prompt assessment of drain position, residual loculations, additional collections and continuing enteric leakage.