Diagnosis of spontaneous bacterial peritonitis in infants and children with chronic liver disease: A cohort study

BACKGROUND: Spontaneous bacterial peritonitis (SBP) is a serious complication in infants and children with chronic liver disease (CLD); however its diagnosis might be difficult. We aimed to study the feasibility of diagnosing SBP by routine ascitic fluid tapping in infants and children with CLD. METHODS: We enrolled thirty infants and children with biopsy-proven CLD and ascites. Ascitic fluid was examined for biochemical indices, cytology and cell count. Aerobic and anaerobic bacteriological cultures of ascitic fluid were preformed. Direct smears were prepared from ascitic fluid deposit for Gram and Zheil-Nelson staining. RESULTS: Patients were divided into three groups: Group I included five patients with SBP in which the cell count was ≥ 250/mm(3 )and culture was positive (16.7%), Group II, eight patients with culture negative neutrocytic ascites (CNNA) with cells ≥ 250/mm(3 )and negative culture (26.7%) and Group III, seventeen negative patients (56.6%) in which cells were <250/mm(3 )and culture was negative. None of our patients had bacteriascites (i.e. culture positive with cells <250/mm(3)). Presence of fever was significantly higher in SBP and CNNA. The mean lactate dehydrogenase (LDH) level was significantly higher in ascitic fluid in the infected versus sterile cases (p < 0.002). A ratio of ascitic/serum LDH ≥ 0.5 gave a sensitivity of 80%, specificity of 88%, positive predictive value (PPV) of 66.7%, negative predictive value (NPV) of 93.7% and accuracy of 63.3%. The mean pH gradient (arterial - ascitic) was significantly higher in SBP and CNNA cases when compared to the negative cases (p < 0.001). Ascitic fluid protein level of ≤ 1 gm/dl was found in 13/30 (43.3%) of studied cases with a sensitivity of 100%, specificity of 64.7%, PPV of 45.5%, NPV of 100% and diagnostic accuracy of 53.3% (p = 0.0001). CONCLUSIONS: SBP is a rather common complication in children with CLD. Culture of the ascitic fluid is not always diagnostic of infection. Biochemical parameters of the ascitic fluid definitely add to the diagnostic accuracy. LDH ascitic/serum ratio ≥ 0.5, an arterial-ascitic pH gradient ≥ 0.1 and total ascitic fluid protein ≤ 1 gm/dl are the most significant parameters suggesting infection.