Diagnosis is made by paracentesis (needle aspiration of the ascitic fluid). SBP is diagnosed if the fluid contains neutrophils (a type of white blood cell) at greater than 250 cells per mm3 (equals a cell count of 250 x106/L) fluid in the absence of another reason for this (such as inflammation of one of the internal organs or a perforation).[1][15] The fluid is also cultured to identify bacteria. If the sample is sent in a plain sterile container 40% of samples will identify an organism, while if the sample is sent in a bottle with culture medium the sensitivity increases to 72–90%.[15]