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Intra-abdominal infection and peritonitis
Primary peritonitis (SBP in cirrhosis) is treated with antibiotics alone, but secondary peritonitis — from a perforation or a leak — requires source control (surgery or drainage) as early as possible; after good source control about 4 days of antibiotics are enough.
Why it matters in the exam
Questions first test the distinction between the three types: primary (SBP) — in a cirrhotic patient with ascites, a single organism, ascitic neutrophils of 250 or more, antibiotics only; secondary — organ perforation, anastomotic leak or abscess, mixed infection, treated by source control; and tertiary — persistent or recurrent infection in an ICU patient after previous treatment, with resistant bacteria and fungi. An important trap is a cirrhotic patient in whom "SBP" is really a perforation — fluid with several organisms, high protein, low glucose and high LDH requires CT.
The second part is treatment: in a septic patient source control should be achieved promptly, usually within a few hours; a contained abscess is drained percutaneously, and generalised peritonitis needs surgery. Antibiotics cover Gram-negative organisms and anaerobes, and the STOP-IT trial showed that after adequate source control about 4 days are enough — longer courses do not improve outcome. Persisting fever or leucocytosis after treatment calls for CT to look for a residual abscess, not just longer antibiotics.
Key points
- Primary (SBP) — antibiotics and albumin, no surgery.
- Secondary — source control (surgery or drainage) and antibiotics.
- After source control — about 4 days of antibiotics.
- Tertiary — ICU patient, resistant bacteria and fungi.
- Persisting fever — CT for a residual abscess.
Summary table
| Type | Background and findings | Treatment |
|---|---|---|
| Primary (SBP) | Cirrhosis with ascites; ascitic neutrophils 250 or more; single organism | Antibiotics (ceftriaxone) and albumin; no surgery |
| Secondary | Perforation, anastomotic leak, abscess; mixed infection | Source control (surgery or drainage) and antibiotics for about 4 days after control |
| Tertiary | ICU patient, infection persisting after treatment | Search for a source, cultures, cover for resistant bacteria and fungi |
| Contained abscess | Localised collection on CT | Percutaneous drainage and antibiotics |
| Suspected perforation in a cirrhotic patient | Several organisms in the fluid, glucose below 50 mg/dL, protein above 1 g/dL, high LDH | CT and surgery according to the finding |
A free exam question
A 72-year-old male is brought to the ER due to left lower quadrant abdominal pain with fever of 38.5°C. On examination - left lower quadrant peritonitis. Blood pressure 120/80 mmHg, pulse 90/min. WBC – 15,000. Abdominal CT demonstrates thickening of the sigmoid and adjacent 5 cm fluid collection with small air bubble. Which of the following is the most appropriate treatment?
- A. Laparotomy and sigmoid resection
- B. Laparoscopic Hartmann’s procedure and abscess drainage
- C. Percutaneous abscess drainage
- D. Laparoscopic abdominal cavity lavage
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Sources
- Surgical Infection Society revised guidelines on the management of intra-abdominal infection, 2017 — Source control and antimicrobial therapy
- STOP-IT trial, New England Journal of Medicine, 2015 — Trial of short-course antimicrobial therapy for intra-abdominal infection
- Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock, 2021 — Source control
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.