A 52-year-old man is admitted to the hospital due to fatigue and abdominal discomfort. The patient has had no nausea, vomiting, constipation, or diarrhea. Medical history is significant for cirrhosis due to chronic alcohol use. Medications include spironolactone and furosemide. He had an inguinal hernia repaired 20 years ago. Temperature is 37.9 C (100.2 F), blood pressure is 102/68 mm Hg, and pulse is 106/min. The patient is awake, alert, and oriented to time, place, and person but is unable to successfully perform a timed connect-the-numbers test. Auscultation of the heart and lungs is normal. Abdominal examination shows moderate ascites with diffuse tenderness to palpation. There is no rigidity or rebound tenderness. Bowel sounds are decreased. Rectal examination is normal with guaiac-negative brown stool. Abdominal x-ray reveals dilated loops of small and large bowel with air in the colon and rectum. Which of the following is the most likely diagnosis in this patient?
Spontaneous bacterial peritonitis | |
Clinical presentation |
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Diagnosis from ascitic fluid |
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Treatment |
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PMN = polymorphonuclear leukocytes; SAAG = serum-ascites albumin gradient; SBP = spontaneous bacterial peritonitis. | |
This patient with ascites (due to cirrhosis) has abdominal tenderness and a subtle alteration in mental status (ie, inability to complete a psychometric test). Along with low-grade fever, these findings raise concern for spontaneous bacterial peritonitis (SBP), which can present on a spectrum of severity from asymptomatic to septic shock.
In contrast to peritonitis caused by bowel perforation, SBP is likely caused by enteric bacteria translocation (eg, Escherichia coli) or hematogenous spread (eg, pneumococcal pneumonia). It often presents with only mild abdominal tenderness without rigidity or rebound tenderness, possibly from ascites serving as a cushion between the parietal and visceral peritoneal surfaces. SBP, particularly if severe, can be accompanied by paralytic ileus, as in this patient with decreased bowel sounds and x-ray findings of dilated loops of bowel.
Because SBP can have a subtle presentation, there should be a low threshold for obtaining a diagnostic paracentesis with fluid analysis in patients with ascites. SBP is diagnosed based on an ascitic fluid neutrophil count of ≥250/mm3. Treatment requires the administration of empiric intravenous antibiotics with reliable coverage against potentially causative organisms; third-generation cephalosporins (eg, ceftriaxone) are typically used.
(Choice A) Acute pancreatitis, commonly caused by heavy alcohol use, can also result in abdominal pain and fever (in severe cases). However, the pain is typically epigastric and radiates to the back; nausea and vomiting are usually present.
(Choice B) Alcoholic hepatitis can also cause fever (due to cytokine release from injured hepatocytes), abdominal pain, ascites, and mental status changes. However, tenderness is typically located in the right upper quadrant rather than diffusely throughout the abdomen. Furthermore, most patients have obvious jaundice due to significantly elevated bilirubin levels.
(Choice C) Peptic ulcer perforation leads to the leakage of gastric contents into the peritoneal cavity, which results in severe abdominal pain with rigidity and rebound tenderness; these findings are absent in this patient. In addition, abdominal x-ray would likely reveal free air under the diaphragm.
(Choice D) Small bowel obstruction would demonstrate only dilated loops of small bowel (without dilated loops of large bowel) on x-ray; also, nausea and vomiting would be expected, and bowel sounds are initially high-pitched.
Educational objective:
Abdominal tenderness and any alteration in mental status should raise suspicion for spontaneous bacterial peritonitis. Rigidity or rebound tenderness may be absent due to ascites serving as a cushion between the parietal and visceral peritoneal surfaces. Empiric intravenous antibiotics should be administered if diagnostic paracentesis shows ≥250/mm3 neutrophils.