Introduction

The definition, diagnosis and management of primary peritonitis (PP) has evolved considerably as improvements in diagnosis and medical imaging increasingly clarify the source of abdominal sepsis. This chapter will outline the current definition of PP and summarize our understanding of peritonitis without a traditional source.

What is primary peritonitis?

Primary peritonitis is a rare cause of peritonitis resulting from an infectious process involving the peritoneal cavity in the absence of an intra-abdominal source. It is typically associated with ascites [1][2][3]. It is also referred to as spontaneous peritonitis, idiopathic peritonitis or spontaneous ascitic fluid infection.

What differentiates primary peritonitis from more traditional forms of peritonitis?

Whereas traditional peritonitis originates secondarily from an intra-abdominal processes within organs such as the appendix, colon or biliary tree, PP presumably develops from lymphatic or hematogenous routes or via an ascending vaginal source [4][5][6][7]. Most cases occur in children with chronic illness associated with ascites (e.g. nephrotic syndrome, chronic liver disease) with a smaller subset of healthy children being affected [8][9][10]. Distinguishing PP from secondary or tertiary peritonitis is critical as PP infrequently requires surgical management in contrast to traditional forms of peritonitis [3]. Secondary peritonitis from a perforated viscus should be sought in cases with a positive peritoneal fluid Gram stain for multiple organisms. Primary peritonitis is typically associated with a single organism although 60% of cultures are negative [11]. Gram positive and Gram negative organisms predominate in PP; the presence of anaerobes should only occur in secondary peritonitis [12].