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Basic Information ⬇

AUTHOR: Ghamar Bitar, MD

Definition

Peritonitis refers to the acute onset of severe abdominal pain caused by peritoneal inflammation.

Secondary peritonitis is peritonitis stemming from another condition; commonly a defect in an abdominal viscus.

Synonyms

Acute abdomen

Surgical abdomen

ICD-10CM CODES
K65.0Generalized (acute) peritonitis
K65.8Other peritonitis
K65.9Peritonitis, unspecified
A18.31Tuberculous peritonitis
A54.85Gonococcal peritonitis
A74.81Chlamydial peritonitis
K35.2Acute appendicitis with generalized peritonitis
K35.3Acute appendicitis with localized peritonitis
K65.2Spontaneous bacterial peritonitis
N73.3Female acute pelvic peritonitis
N73.4Female chronic pelvic peritonitis
N73.5Female pelvic peritonitis, unspecified
P78.1Other neonatal peritonitis
Epidemiology & Demographics

Common presentation as a result of diverse etiologies; for example, 5% to 10% of the population has acute appendicitis at some point in their lives.

Physical Findings & Clinical Presentation

  • Acute abdominal pain
  • Abdominal distention and ascites
  • Abdominal rigidity, rebound, and guarding
  • Altered mental status
  • Fever, chills
  • Exacerbation with movement
  • Anorexia, nausea, and vomiting
  • Constipation or diarrhea
  • Decreased bowel sounds
  • Hypotension and tachycardia
  • Tachypnea, dyspnea
Etiology

  • One of the early steps is disturbance in gut flora with overgrowth and extraintestinal organismal overtake. Most common are gram-negative bacteria (Escherichia coli, Enterobacter, Klebsiella, Proteus), gram-positive bacteria (enterococci, streptococci, staphylococci), anaerobic bacteria (Bacteroides, Clostridioides), and fungi.
  • It can be acute perforation peritonitis: Gastrointestinal perforation, intestinal ischemia, pelvic peritonitis, and other forms.
  • Postoperative peritonitis: Anastomotic leak, accidental perforation, and devascularization.
  • Posttraumatic peritonitis: After blunt or penetrating abdominal trauma.

Diagnosis ⬆ ⬇

Differential Diagnosis

  • Postoperative: Abscess, sepsis, bowel obstruction, injury to internal organs
  • Gastrointestinal: Perforated viscus, appendicitis, inflammatory bowel disease, infectious colitis, diverticulitis, acute cholecystitis, peptic ulcer perforation, pancreatitis, bowel obstruction
  • Gynecologic: Ruptured ectopic pregnancy, pelvic inflammatory disease, ruptured hemorrhagic ovarian cyst, ovarian torsion, degenerating leiomyoma
  • Urologic: Nephrolithiasis, interstitial cystitis
  • Miscellaneous: Abdominal trauma, penetrating wounds, infections caused by intraperitoneal dialysis
Workup

  • Acute peritonitis is mainly a clinical diagnosis based on patient history and physical examination.
  • Laboratory and imaging studies assist in determining the need for and type of intervention. Typical pretreatment peritoneal fluid and blood culture results in peritonitis are summarized in Table E1.
  • If patient is hemodynamically unstable, immediate diagnostic laparotomy should be performed in lieu of adjuvant diagnostic studies.

a TABLE E1 Typical Pretreatment Peritoneal Fluid and Blood Culture Results in Peritonitis

Peritonitis
PrimarySecondaryTertiaryPeritoneal Dialysis (PD)Tuberculosis (TB)
TypicalCNNAMNBAPBA
Leukocyte counta≥250 PMN<250 PMN≥250 PMN≥250 PMN≥100 totalb usually >50% PMN150-4000 total usually lymphocytes
GramVariablecNegativeVariableUsually positiveVariableVariablePositive 10%-50%Negative AAFB smear has low yield
CulturePositiveNegativePositivePositivePositiveVariablePositiveNegative <20% culture positive
OrganismsMonomicrobialVariableMonomicrobialPolymicrobialPolymicrobialPolymicrobialMonomicrobialMonomicrobial
Total protein<1 g/dlVariableNormalNormal>1 g/dlVariableVariable>3 g/dl
Glucose≥2.8 mmol/LVariableNormalNormal<2.8 mmol/LVariableVariableLow
LDHWithin serum rangeVariableNormalNormal>SerumVariableVariableHigh (>90 U/ml)
Blood culture75% positiveNegativeNegativeNegativeNegativeNegativeNegativeNegative

NOTE: Lactate and pH are unhelpful.

CNNA, Culture-negative neutrocytic ascites; LDH, lactate dehydrogenase; MNBA, monomicrobial nonneutrocytic bacterascites; PBA, polymicrobial bacterascites; PMN, polymorphonuclear leukocyte.

Corrected PMN count should be calculated if aspirate is traumatic (bloody) due to entry of excess PMN: 1 PMN subtracted for every 250 RBC/mm3.

b Eosinophilia may be seen after tube placement (and rarely in some cases of fungal disease).

c Insensitive with high false-positive rate.dIncrease bacterial yield (up to 100%) if inoculated early into enrichment media.

From Spec A et al: Comprehensive review of infectious diseases, Philadelphia, 2019, Elsevier.

Laboratory Tests

  • Ascitic fluid testing
    1. Anaerobic and aerobic cultures
    2. Cell count and differential
    3. Albumin, protein, amylase, bilirubin
    4. Glucose
    5. Lactate dehydrogenase (LDH)
  • CBC: Leukocytosis, left shift, anemia
  • SMA7: Electrolyte imbalances, kidney dysfunction
  • Liver function tests: Indicative of cirrhosis as ascites from liver disease, cholelithiasis
  • Amylase: Pancreatitis
  • Blood cultures: Bacteremia, sepsis
  • Blood gas: Respiratory versus metabolic acidosis
  • Urinalysis and culture: Urinary tract infection
  • Cervical cultures for gonorrhea and Chlamydia
  • Urine/serum human chorionic gonadotropin
Imaging Studies

  • Abdominal series: Free air from perforation, small or large bowel dilation from obstruction, identification of fecalith
  • Chest x-ray examination: Elevated diaphragm, pneumonia
  • Pelvic/abdominal ultrasound: Abscess formation, abdominal mass, intrauterine versus ectopic pregnancy, identify free fluid suggestive of hemorrhage or ascites
  • Computed tomography (CT): Mass, ascites

Treatment ⬆ ⬇

Nonpharmacologic Therapy

  • Intravenous (IV) hydration to correct dehydration, hypovolemia
  • Blood transfusion to correct anemia from hemorrhage
  • Nasogastric decompression, especially if obstruction is present
  • Oxygen: Intubation if necessary
  • Bed rest
Acute General Rx

  • Surgery to correct underlying pathology, such as controlling hemorrhage, correcting perforation, and draining abscess
  • Broad-spectrum antibiotics to cover both gram-negative aerobic and gram-negative anaerobic bacteria:
    1. Mild-moderate disease: Piperacillin-tazobactam 3.375 g IV q6h or 4.5 g IV q8h orticarcillin-clavulanate 3.1 g IV q6h. Alternative agents are ciprofloxacin 400 mg IV q12h or levofloxacin 750 mg IV q24h plus metronidazole 1 g IV q12h.
    2. Severe life-threatening disease: Imipenem 500 mg IV q6h or meropenem 1 g IV q8h. Alternative agents are ampicillin plus metronidazole plus ciprofloxacin.
    3. Antibiotic therapy should be tailored to culture results and sensitivities.
  • Pain control: Morphine or meperidine as needed (hold until diagnosis confirmed)
Disposition

Depends on etiology of peritonitis, age of patient, coexisting medical disease, and duration of process before presentation.

Referral

Surgical consultation is required in all cases of acute peritonitis.

Pearls & Considerations ⬆

CT scan guides therapeutic approach and should be considered as the primary imaging study if available. As with forms of sepsis, early administration of broad-spectrum antibiotics, fluid resuscitation, and rapidly obtaining anatomic source control (when appropriate) will lead to improved outcomes.