Peritoneal fluid analysis laboratory interpretation.pptx

peritoneal fluid analysis

1. Peritoneal cavity is a potential space in the abdomen lined by mesothelial cells and normally containing about 30- 50ml of serous fluid The fluid is an ultrafiltrate of plasma and its formation is dependent upon hydrostatic pressure, plasma oncotic pressure, and capillary permeability Pathological accumulation of fluid in peritoneal cavity is called as ascites, and the accumulated fluid is called as ascitic fluid

2. Causes of Ascites Transudate (increased hydrostatic pressure or plasma oncotic pressure) Exudate (Increased capillary permeability or lymphatic obstruction) 1. Cirrhosis of liver 1. Bacterial peritonitis (primary or secondary) 2. Congestive cardiac failure 2. Tuberculosis 3. Hypoproteinemia 3. Malignancy (lymphoma, hepatoma, metastatic carcinoma) 4. Abdominal injury 5. Biliary peritonitis (rupture of gallbladder) 6. Pancreatitis 7. Chylous ascites (obstruction of or injury to thoracic duct)

3. Indications for Abdominal Paracentesis Abdominal paracentesis refers to removal of ascitic fluid through puncture of the peritoneal cavity Indications 1.All patients with new-onset ascites 2. At admission in all patients with ascites for detection of asymptomatic infection 3. All patients with ascites who develop clinical features of bacterial infection, hepatic encephalopathy, gastrointestinal hemorrhage, or impairment of renal function. 4. Symptomatic ascites (therapeutic paracentesis)

4. Collection of sample Presence of ascites can usually be detected by clinical examination; if clinical examination is not definitive, ultrasound can be helpful. Ultrasonography can also be useful for determining the cause of ascites. A hollow needle is inserted through the abdominal wall (usually left lower quadrant of abdomen below the border of shifting dullness) into the peritoneal cavity and fluid (20-50 ml) is removed under aseptic precautions. Sites for paracentesis (blue filled circles)

5. For cytology, to maximize the yield of malignant cells, 100 ml should be submitted For cell count sample is collected in EDTA-containing tube For microbiologic culture, sample is inoculated in blood culture bottles at bedside Complications of the procedure include hemorrhage, perforation of viscus, and introduction of infection Evidence of fibrinolysis or of disseminated intravascular coagulation in liver disease is a contraindication for paracentesis

6. Examination of Ascitic Fluid Laboratory analysis of ascitic fluid helps in the differential diagnosis of ascites A variety of tests can be carried out; however, the tests should be decided in an individual patient according to the clinical presentation The commonly performed tests include estimation of total proteins and albumin, cell count, cytological examination, and bacterial culture

7. Appearance Transudates are pale yellow or strawcolored and clear, whereas exudates are opaque or turbid. Turbid fluid results from leucocytes, malignant cells, or proteins. Bloody or hemorrhagic fluid indicates traumatic tap, recent surgery, abdominal trauma, or malignancy A traumatic tap shows gradual clearing of fluid during aspiration. Milky or chylous fluid results from obstruction of lymphatic duct due to inflammation or malignancy (lymphoma, carcinomatosis), or from abdominal injury

8. Chemical examination Proteins : Traditionally, fluid is called as a transudate if protein content is low, and an exudate if its protein content is high However, this criterion alone is not always sufficient. In ascitic fluid, distinction between transudates and exudates cannot be reliably made by estimation of proteins A better indicator is albumin gradient (calculated as serum albumin minus ascitic fluid albumin done on the same day) Total protein concentration in ascitic fluid can be helpful in differentiating spontaneous (total protein <1gm/dL) from secondary bacterial peritonitis (total protein >1gm/dL)

9. Lactate dehydrogenase Lactate dehydrogenase in ascitic fluid is elevated in spontaneous bacterial peritonitis (i.e. there is no obvious source of infection), secondary bacterial peritonitis (i.e. identifiable source of infection is present), and in peritoneal carcinomatosis Amylase Normally, amylase in ascitic fluid is similar to serum amylase If ascitic fluid amylase is three times greater than serum amylase, ascites is most likely to be due to pancreatic disease such as acute pancreatitis

10. Bilirubin Ascitic fluid bilirubin greater than 6.0 mg/ dl and ascitic fluid bilirubin/serum bilirubin ratio greater than 1.0 indicate perforation of biliary tract (biliary peritonitis) Ascitic fluid is bile-stained

11. Cell count Cell count is usually done to distinguish cirrhotic ascites from spontaneous bacterial peritonitis In ascitic fluid, total leukocyte count > 500/ml and absolute neutrophil count >250/ml constitute the presumptive evidence of spontaneous bacterial peritonitis

12. Differentiation of spontaneous from secondary bacterial peritonitis

13. Parameter Spontaneous bacterial peritonitis Secondary bacterial peritonitis Obvious source of infection Absent Present, e.g. perforation of viscus, abscess Total ascitic fluid proteins <1gm/dL >1gm/dl Severity Less severe More severe Culture Single organism Multiple organisms Treatment Rapid response to antibiotics Requires surgical treatment

14. Microbiological examination Gram smear is positive in 25% cases of spontaneous bacterial peritonitis If ascitic fluid is inoculated in blood-culture bottles at bedside, sensitivity of isolation rises to 85% (as compared to conventional method of inoculation in broth and agar plates in laboratory) In spontaneous bacterial peritonitis, a single organism is isolated, while secondary bacterial peritonitis is polymicrobial In case of tuberculosis, Ziehl- Neelsen stain has sensitivity of 25-30%, while culture is positive in about 50% of cases Laparoscopic biopsy is more helpful in diagnosis of tuberculous peritonitis

15. Cytological examination Cytological examination of peritoneal fluid can detect 40-65% cases of malignant ascites

16. Ascitic fluid findings in various diseases