S2542 Hold the Scalpel: Pneumoperitoneum as a Result of Spontaneous Bacterial Peritonitis

Abstract

INTRODUCTION: Differentiating spontaneous bacterial peritonitis (SBP) from secondary bacterial peritonitis is essential as the management is critically different. SBP is usually caused by one organism while secondary bacterial peritonitis is polymicrobial. Runyon’s criteria are helpful in differentiating the two entities based on ascites fluid analysis. We review a case of a patient presenting with abdominal pain and found to have pneumoperitoneum and presumed secondary bacterial peritonitis. With further work up was it determined that she had developed pneumoperitoneum from SBP. CASE DESCRIPTION/METHODS: A 53 year old female with past medical history of alcoholic liver cirrhosis presented to the hospital with abdominal pain of 4 weeks duration. Vital signs were stable. Physical examination was significant for abdominal tenderness. Lab work was notable for leukocytosis, total bilirubin of 5.9mg/dl and direct bilirubin of 3.3mg/dl. Abdominal CT scan showed pneumoperitoneum and ascites (Image 1). She was started on cefepime, metronidazole and IV hydration. Exploratory laparotomy and upper endoscopy were performed. No obvious perforation was found. Ascites fluid analysis showed LDH 70 U/L and total protein 1 g/dL. Ascites fluid cell count: lymphocyte 2%, neutrophils 88%, RBCs 48/ uL, nucleated cell count 668 × 0.88/uL. Ascitic fluid cultures grew Candida albicans and Bacteriodes Ovatus. Patient was transitioned to fluconazole, ceftriaxone and metronidazole for polymicorbial coverage. Her symptoms gradually improved. A diagnosis of SBP due to gas forming bacteria was made and patient was started on lifelong antibiotic prophylaxis. DISCUSSION: Differentiating SBP from secondary bacterial peritonitis is not always straight forward. In our case, patient presented with pneumoperitneuim that led to presumptive diagnosis of secondary bacterial peritonitis. She underwent extensive workup without identifying organ perforation. Ascitic protein level was not greater than 1g/L and LDH was not greater than the upper limit of normal making the diagnosis of secondary bacterial peritonitis less likely per Runyon’s criteria. Peritoneal fluid grew Bacteriodes Ovatus which are gram negative gas- forming anaerobes. Bacterial growth in the peritoneal fluid results in pneumoperituim giving a false impression of hollow viscus perforation. Careful and timely work up is necessary in these patients.Image 1.: Cross sectional view of contrast CT scan of the abdomen showing air under the diaphragm.