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Ascitic fluid analysis (SAAG)

Body Fluids · also called Peritoneal fluid analysis, Paracentesis fluid

What it measures

Analyses peritoneal fluid to find the cause of ascites and detect infection. The serum-ascites albumin gradient (SAAG) separates portal hypertension from other causes.

Specimen and preparation

Specimen: Ascitic fluid in sterile tubes and blood-culture bottles at the bedside; paired serum albumin
Tube: Other top
Preparation: Inoculate blood-culture bottles at the bedside; paired serum albumin the same day.

Reference range

Group	Range
SAAG (serum − ascitic albumin), portal hypertension	≥ 1.1 g/dL
Neutrophils	< 250 cells/µL

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

SAAG ≥ 1.1: cirrhosis, heart failure, Budd-Chiari
Neutrophils ≥ 250/µL: spontaneous bacterial peritonitis
High amylase: pancreatic ascites
High ADA/lymphocytes: tuberculous peritonitis

Causes of low values

SAAG < 1.1: peritoneal carcinomatosis, TB, pancreatitis, nephrotic syndrome

Method

Albumin, total protein, cell count with neutrophil count, Gram stain, culture, ADA, amylase, cytology

Good to know

Ascitic protein < 1.5 g/dL in cirrhosis indicates higher risk of SBP.

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