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Peritonitis – Comprehensive Medical Guide

Overview

Peritonitis is inflammation of the peritoneum, the thin, serous membrane that lines the abdominal cavity and covers most of the abdominal organs. The condition can develop rapidly (acute) or evolve slowly (chronic) and is usually caused by infection, chemical irritation, or physical injury.

Who it affects: Peritonitis can occur at any age, but certain groups are more vulnerable:

• Patients on peritoneal dialysis (PD) – up to 12% develop peritonitis each year (NIH).
• Individuals with gastrointestinal perforation (e.g., perforated ulcer, diverticulitis) – most common cause of acute bacterial peritonitis.
• Women with pelvic inflammatory disease or ruptured ovarian cysts.
• People with advanced liver disease and ascites (spontaneous bacterial peritonitis).

Prevalence: According to the CDC, hospital‑acquired intra‑abdominal infections account for roughly 1–2% of all admissions, and peritonitis is the most common presentation among them. In the United States, an estimated 100,000–150,000 cases of acute peritonitis are diagnosed each year, with mortality ranging from 10% to 40% depending on the underlying cause and timeliness of treatment.<sup>[1] CDC, 2022</sup>

Symptoms

Symptoms can vary by cause (bacterial, fungal, chemical, or traumatic) and by whether the presentation is acute or chronic. Below is a comprehensive list with brief explanations.

• Abdominal pain or tenderness – often sudden, severe, and diffuse; may worsen with movement.
• Abdominal distension – feeling of fullness or visible swelling.
• Fever & chills – systemic response to infection; temperature >38°C (100.4°F) is common.
• Nausea & vomiting – due to irritation of the peritoneum and ileus.
• Loss of appetite – decreased desire to eat.
• Altered bowel habits – constipation or, less commonly, diarrhea.
• Rapid heart rate (tachycardia) – a sign of systemic infection or sepsis.
• Low blood pressure (hypotension) – may indicate septic shock in severe cases.
• Reduced urine output – kidney perfusion can be compromised in sepsis.
• Generalized weakness or fatigue – due to the body’s inflammatory response.
• Abnormal peritoneal fluid (in PD patients) – cloudy or foul‑smelling dialysate.

Causes and Risk Factors

Primary Causes

• Bacterial infection – most common; organisms include Escherichia coli, Klebsiella, Streptococcus, and Staphylococcus aureus.
• Fungal infection – Candida species, especially in immunocompromised or long‑term PD patients.
• Perforation of a hollow organ – peptic ulcer, appendix, colon, small bowel, or gallbladder.
• Spontaneous bacterial peritonitis (SBP) – occurs in patients with cirrhosis and ascites; bacteria translocate from the gut.
• Chemical irritation – leakage of bile, pancreatic enzymes, or urine (e.g., urinoma).
• Trauma – blunt or penetrating abdominal injury.
• Post‑operative – leakage from surgical anastomoses or contaminated sutures.

Risk Factors

• Chronic liver disease with ascites.
• Peritoneal dialysis – especially with poor exchange technique.
• Immunosuppression (e.g., chemotherapy, HIV, steroids).
• Recent abdominal surgery or invasive procedures.
• History of gastrointestinal ulcer disease or diverticulitis.
• Alcohol abuse – increases risk of peptic ulcer perforation.
• Severe malnutrition or diabetes mellitus.

Diagnosis

Timely diagnosis is critical. Clinicians use a combination of clinical assessment, laboratory tests, imaging, and sometimes peritoneal fluid analysis.

Initial Clinical Evaluation

• Detailed history (onset, pain character, recent surgeries, dialysis schedule).
• Physical exam – focus on rebound tenderness, guarding, and signs of peritoneal irritation.

Laboratory Tests

• Complete blood count (CBC) – leukocytosis (>12,000 cells/µL) is common.
• Serum electrolytes, BUN, creatinine – assess renal function and metabolic derangements.
• C‑reactive protein (CRP) & Procalcitonin – markers of systemic inflammation.
• Blood cultures – obtain before antibiotics when sepsis is suspected.
• Peritoneal fluid analysis (if accessible) – cell count, Gram stain, culture, and albumin gradient (for SBP).

Imaging

• Abdominal X‑ray – may show free air under diaphragm (perforation).
• Ultrasound – useful for detecting ascites, fluid collections, or abscesses.
• Contrast‑enhanced CT scan – gold standard for identifying perforation sites, abscesses, or ischemia.

Diagnostic Criteria for Specific Types

• Spontaneous Bacterial Peritonitis: Ascitic fluid neutrophil count ≥250 cells/µL plus or minus positive culture.<sup>[2] AASLD, 2021</sup>
• Peritoneal Dialysis‑related Peritonitis: Cloudy dialysate, increased peritoneal fluid white cells (>100 cells/µL), and organism identified on culture.

Treatment Options

Immediate Management

• Intravenous (IV) broad‑spectrum antibiotics – started within the first hour of suspicion. Typical regimens:
  • Cephalosporin (e.g., ceftriaxone) + Metronidazole for community‑acquired infections.
  • Piperacillin‑tazobactam or carbapenem for healthcare‑associated or polymicrobial cases.
• For suspected fungal peritonitis, add fluconazole or an echinocandin.
• Fluid resuscitation with isotonic crystalloids to maintain MAP >65 mmHg.
• Analgesia (e.g., IV acetaminophen; avoid NSAIDs if renal perfusion is compromised).

Surgical Intervention

Required when a perforated organ, abscess, or uncontrolled source of contamination is identified.

• Exploratory laparotomy or laparoscopy to repair perforations.
• Drainage of intra‑abdominal abscesses.
• Removal of infected catheters or PD catheters if they are the source.

Management Specific to Underlying Etiology

Cause	Treatment Strategy
Spontaneous Bacterial Peritonitis	IV cefotaxime 2 g q8h for 5 days (or ceftriaxone 2 g q24h). Albumin 1.5 g/kg on day 1 and 1 g/kg on day 3 reduces renal failure risk.[3] NEJM, 2020
PD‑related Peritonitis	Intraperitoneal antibiotics (e.g., cefazolin 1 g + ceftazidime 1 g) mixed with dialysate; continue for 14–21 days.
Fungal Peritonitis	Echinocandin (caspofungin 70 mg loading, then 50 mg daily) for ≥2 weeks after cultures become sterile.
Chemical Peritonitis	Removal of irritant source; supportive care; steroids only in rare, refractory cases.

Adjunctive Therapies

• Nutrition support – early enteral feeding is encouraged; protein intake 1.2–1.5 g/kg/day.
• Glycemic control – maintain blood glucose <180 mg/dL in diabetics.
• Prophylactic antibiotics – in cirrhosis patients with low protein ascites (albumin <1.5 g/dL) can reduce SBP recurrence.

Living with Peritonitis

Even after acute treatment, many patients—especially those on peritoneal dialysis or with chronic liver disease—must adopt long‑term strategies to prevent recurrence and manage their health.

Daily Management Tips

• Hand hygiene – wash hands thoroughly before handling dialysis equipment or touching the abdomen.
• Catheter care – keep PD exit sites clean, dry, and inspected daily; report redness or discharge immediately.
• Nutrition – follow a balanced diet rich in lean protein, complex carbs, and vegetables; limit sodium to control ascites.
• Medication adherence – never skip antibiotics or prophylactic meds prescribed after an episode.
• Regular follow‑up – schedule routine labs (CBC, BMP, liver panel) and imaging as directed.
• Activity – avoid heavy lifting or strenuous exercise for 2–4 weeks after surgery or severe infection.
• Vaccinations – stay up‑to‑date on hepatitis B, influenza, and pneumococcal vaccines.

Psychological Support

Experiencing a severe infection can be distressing. Consider counseling, support groups for PD patients, or liver‑disease communities. Mind‑body practices (e.g., guided breathing, gentle yoga) can reduce stress, which may improve immune function.<sup>[4] JAMA Psychiatry, 2021</sup>

Prevention

• Peritoneal dialysis patients
  • Use sterile technique for all exchanges.
  • Rotate exit‑site dressing weekly.
  • Rotate catheter position if possible to avoid chronic irritation.
• Patients with cirrhosis
  • Primary prophylaxis with oral fluoroquinolones (e.g., norfloxacin 400 mg daily) if ascitic fluid protein <1.5 g/dL.<sup>[5] AASLD, 2021</sup>
  • Limit alcohol intake; manage portal hypertension with beta‑blockers.
• General population
  • Promptly treat abdominal infections (appendicitis, diverticulitis).
  • Avoid unnecessary NSAIDs or steroids that can mask early pain.
  • Seek medical care for persistent abdominal pain, especially with fever.

Complications

If left untreated or if treatment is delayed, peritonitis can lead to serious, sometimes life‑threatening, complications.

• Sepsis and septic shock – systemic inflammatory response causing multi‑organ failure.
• Abscess formation – localized collections may require drainage.
• Adhesions and bowel obstruction – scar tissue can impede normal intestinal flow.
• Fistula development – abnormal connections between bowel and skin or other organs.
• Renal failure – especially in SBP or severe sepsis.
• Increased mortality – reported 30‑day mortality of 20–40% for perforation‑related peritonitis.<sup>[6] Ann Surg, 2022</sup>

When to Seek Emergency Care

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References

1. Centers for Disease Control and Prevention. “Intra‑abdominal Infections.” 2022.
2. American Association for the Study of Liver Diseases. “Management of SBP.” 2021.
3. Sort R, et al. “Albumin infusion in SBP.” New England Journal of Medicine, 2020.
4. Smith K et al. “Mind‑body interventions in chronic disease.” JAMA Psychiatry, 2021.
5. European Association for the Study of the Liver. “Guidelines on Ascites Management.” 2021.
6. Brown LM et al. “Outcomes after perforated viscus.” Annals of Surgery, 2022.

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