Spontaneous bacterial peritonitis

Perforated viscus

Cirrhosis

Malignancy

TB

Discussion

Carrying on with theme for Question 5, this is another middle-aged gentleman with liver disease.  This time, the question really is, "what does this ascitic tap mean". The history offered with the results ("exacerbation of liver disease"?) is so uninformative it may as well not exist. 

So: using the 2009 article by Koulaouzidis and Such & Runyon (1998) as the main sources, one can concoct an unordered list which describes the reported findings, and their possible meaning.

• Clear ascitic fluid: probably meaningless. About a third of such people could still have SBP (Aminiahidashti et al, 2014)
• pH not available: that's a pity, because it could have been helpful - a pH < 7.3 seems to be strongly associated with SBP (Gitlin et al, 1982)
• RBC of 0 cells per µL: a good sign, as haemorrhagic ascites (RBC count > 10,000) is prognostically terrible ( Urrunaga et al, 2013). The presence of micro-clots in the fluid suggests that the RBCs were there, but then clotted.
•  WCC in excess of 250 leukocytes/µL without any organisms potentially puts this in the territory of "culture-negative neutrocytic ascites". It meets the cell count criteria for SBP.
• A high ascitic fluid protein and albumin suggest infection or malignancy. An albumin of 18 is too high for "plain" ascites of portal hypetension, as the SAAG (serum-ascites albumin gradient) is expected to be no higher than 11 g/L. So, the albumin should be no higher than 12 in this sample. 
• Ascitic LDH is elevated, also suggesting malignancy or infection. The LDH should be under 400 U/L, and the ascites:serum LDH ratio should be no higher than 0.6. In this scenario the ratio is (480/320) = 1.5.

So, in summary, what could this be?

• Malignancy: there are lots of features
• Bacterial SBP infection with a non-Gram-staining organism, eg. tuberculosis
• Sarcoid-associated ascites
• Pancreatitis-associated ascites
• Abdominal fluid in the presence of bowel obstruction
• It's not ascites! Could this have been urine?