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Ascites


Editorial Board Member: Monika Vyas, M.D.
Deputy Editor-in-Chief: Aaron R. Huber, D.O.
Anthony W.H. Chan, M.B.Ch.B.

Last author update: 28 April 2025
Last staff update: 28 April 2025

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PubMed Search: Ascites

Anthony W.H. Chan, M.B.Ch.B.
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Table of Contents
Definition / general | Essential features | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Diagrams / tables | Clinical features | Diagnosis | Laboratory | Prognostic factors | Case reports | Treatment | Clinical images | Cytology description | Cytology images | Positive stains | Negative stains | Molecular / cytogenetics description | Sample pathology report | Practice question #1 | Practice answer #1 | Practice question #2 | Practice answer #2
Cite this page: Chan AWH. Ascites. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/liverascites.html. Accessed April 29th, 2025.
Definition / general
  • Ascites is pathological fluid accumulation in the peritoneal cavity
Essential features
  • Ascites is pathological fluid accumulation in the peritoneal cavity
  • Causes vary in different countries but cirrhosis is the most common cause
  • It is the most common major complication of cirrhosis, with a prevalence of 10% among patients
ICD coding
  • ICD-10: R18 - ascites
  • ICD-11: ME04 - ascites
Epidemiology
Sites
  • Peritoneal cavity
Pathophysiology
  • Results from a combination of the following factors, which reinforce each other (Clin Liver Dis 2012;16:285)
    • Elevated hydrostatic pressure due to portal hypertension
    • Reduced osmotic pressure due to hypoalbuminemia
    • Renal retention of sodium and water due to activation of renin angiotensin aldosterone system (RAAS)
    • Decreased effective circulatory volume due to ascites
Etiology
  • Varies in different countries (Clin Chem Lab Med 2023;62:1266)
    • In the United States
      • Cirrhosis (84.1%)
      • Heart failure (2.7%)
      • Malignancy (2.4%)
      • Tuberculosis (0.7%)
      • Pancreatic disease (0.4%)
    • In China
Diagrams / tables

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Diagnostic approach

Diagnostic approach

Interpretation of effusion cytology

Interpretation of effusion cytology

Clinical features
  • Abdominal distension with shifting dullness
Diagnosis
  • Physical examination: abdominal distension with shifting dullness
  • Radiological investigation: ultrasound or computed tomography (CT) scan to detect mild (grade 1) ascites (Hepatology 2021;74:1014)
Laboratory
  • Ascitic fluid cell count and differential
    • Polymorphonuclear leukocyte (PMN) count > 250 cells/mm3 in the absence of an intra-abdominal, surgically treatable source of infection indicates spontaneous bacterial peritonitis, which complicates ~12% of cirrhotic patients with ascites (Hepatology 1982;2:399, Dig Liver Dis 2001;33:41)
  • Serum ascites albumin gradient (SAAG) (Am J Gastroenterol 2009;104:1401)
    • ≥ 1.1 g/dL indicates portal hypertension
    • < 1.1 g/dL indicates nonportal hypertension causes including malignancies, tuberculous peritonitis and nephrotic syndrome
Prognostic factors
Case reports
Treatment
  • First line
    • Cessation of alcohol when present
    • Sodium restriction
    • Dual diuretics (usually spironolactone and furosemide)
    • Discontinue nonsteroid anti-inflammatory drugs
    • Evaluation for liver transplantation
  • Second line
    • Discontinue beta blockers, angiotensin converting enzyme inhibitors and angiotensin receptor blockers
    • Serial therapeutic paracentesis
    • Transjugular intrahepatic portosystemic stent shunt (TIPSS)
    • Evaluation for liver transplantation
  • Third line
    • Peritoneovenous shunt
  • Reference: Hepatology 2021;74:1014
Clinical images

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Severe ascites due to cirrhosis

Severe ascites due to cirrhosis

Cytology description
  • Only positive in peritoneal carcinomatosis (sensitivity of 96.7% if 3 samples from different paracentesis procedures) (Hepatology 1988;8:1104)
  • Almost always negative in cirrhotic patients, even those known to have hepatocellular carcinoma (Cytojournal 2009;6:16)
Cytology images

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Ascites fluid cytology

Ascites fluid cytology

Cell block

Cell block

Calretinin   Calretinin

Calretinin

Papanicolaou stained smear   Papanicolaou stained smear

Papanicolaou stained smear

Positive stains
Negative stains
Molecular / cytogenetics description
  • CDKN2A homogenous deletion: differentiating peritoneal mesothelioma from reactive mesothelial cells (sensitivity 10 - 15% and specificity 100%) (Arch Pathol Lab Med 2024;148:1251)
  • Cell free DNA in ascitic fluid could be a source for next generation sequencing in case of malignant ascites (Cancer Cytopathol 2020;128:43)
Sample pathology report
  • Ascitic fluid, cytology:
    • Negative for malignant cells
Practice question #1
What is the most common cause of ascites in the United States?

  1. Cardiac failure
  2. Cirrhosis
  3. Malignancy
  4. Tuberculosis
Practice answer #1
B. Cirrhosis. Over 80% of patients with ascites in the United States are associated with cirrhosis. Answers A, C and D are incorrect because cardiac failure, malignancy and tuberculosis account for 2.7%, 2.4% and 0.7% of cases, respectively (Clin Chem Lab Med 2023;62:1266).

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Reference: Ascites
Practice question #2
Severe ascites


What is the cause of ascites associated with a serum ascites albumin gradient (SAAG) ≥ 1.1 g/dL?

  1. Cirrhosis
  2. Malignancy
  3. Nephrotic syndrome
  4. Tuberculosis
Practice answer #2
A. Cirrhosis. SAAG ≥ 1.1 g/dL indicates portal hypertension, which is associated with cirrhosis (Am J Gastroenterol 2009;104:1401). Answers B, C and D are incorrect because other causes (malignancy, nephrotic syndrome and tuberculosis) are associated with nonportal hypertension (SAAG < 1.1 g/dL).

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Reference: Ascites
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