Role of ultrasonographically guided fine-needle aspiration cytology in the diagnosis of infected pancreatic necrosis

Abstract

Background: Early detection of infected pancreatic necrosis has a major impact on further management and outcome in acute pancreatitis. The aim of this study was to evaluate the clinical value of ultrasonographically guided fine-needle aspiration cytology (FNAC) in patients with necrotizing pancreatitis over an 8-year period. Methods: From January 1988 to September 1996 193 (mean 2·0 (range 1–9) aspirations per patient) prospectively assessed FNACs guided ultrasonographically were performed in 98 patients with necrotizing pancreatitis proven by contrast-enhanced computed tomography. Aspirates were considered infected if either Gram stain and/or culture revealed micro-organisms. Results: Ultrasonographically guided FNAC correctly diagnosed infection in 29 of 33 patients with infected necrosis a median of 13 days after onset of symptoms. Of 61 patients with sterile necrosis 55 were identified correctly as sterile by FNAC. There were six false-positive and four false-negative aspirates of which nine occurred during the first week of the disease. In four patients who did not undergo operation FNAC revealed Gram-negative organisms; however, in the absence of repeated aspirations, the positive results remained unconfirmed. An overall sensitivity of 88 per cent and a specificity of 90 per cent was obtained. No difference was found in biochemical and clinical parameters indicating systemic inflammatory response syndrome before each FNAC between patients with proven sterile or infected necrosis. All patients tolerated the procedure well and no major complications were observed. Conclusion: Ultrasonographically guided FNAC is a fast and reliable technique for the diagnosis of infected necrosis. As complication rates are very low, the procedure can be repeated at short intervals to improve the diagnostic accuracy. Ultrasonographically guided FNAC is recommended for all patients with necrotizing pancreatitis in whom systemic inflammatory response syndrome persists beyond the first week after onset of symptoms.