Value of Gram's stain of cell block material from peritoneal fluid in bacterial peritonitis.
OBJECTIVE: To determine the value of Gram's stain of cell blocks of peritoneal fluid for the diagnosis of bacterial peritonitis. STUDY DESIGN: The results of Gram's stain of 12 cases of culture-positive, frank bacterial peritonitis (FBP) and 11 cases of culture-positive spontaneous bacterial peritonitis (SBP) were compared with 6 cases of culture-negative frank sterile peritonitis and 21 cases of culture-negative spontaneous sterile peritonitis. RESULTS: For both FBP and SBP, Gram's stain had low sensitivity (8% and 9%). Overall, the positive predictive value of Gram's stain for peritonitis was 33%. Hematoxylin-eosin (HE) was just as sensitive but had a positive predictive value of 100%. CONCLUSION: In cell block material of peritoneal fluid, Gram's stain is of little value except to further characterize organisms seen on HE.