ascites

Introduction

The accumulation of excess fluid within the peritoneal cavity.

Etiology

• transudates
  • pathophysiology
    • increased portal venous pressure (portal hypertension)
    • increased lymph production
    • decreased oncotic pressure
    • impaired renal excretion of Na+ & H2O
  • disorders associated with transudative ascites
    • cirrhosis (80%)*
    • right-sided heart failure
      • constrictive pericarditis
    • Budd-Chiari syndrome
    • nephrotic syndrome
    • hypoalbuminemia
    • myxedema
    • Meig's syndrome
• exudates
  • pathophysiology
    • inflammation disrupts capillaries & lymphatics
    • protein leak into peritoneal cavity
    • inflammation superimposed on exudative ascites
  • disorders associated with exudative ascites
    • abdominal tumor
    • abdominal infection
    • peritonitis
    • pancreatitis
    • intestinal perforation
    • lymphatic obstruction
      • trauma, tumor, tuberculosis

* ascites develops in 50% of patients with cirrhosis within 10 years

Pathology

• in ascites due to portal hypertension, blood pressure falls resulting in reduced renal blood flow & glomerular filtration
  • compensatory upregulation of renin-angiotensin system supports blood pressure & renal function

Clinical manifestations

• mild ascites is frequently asymptomatic
• several hundred mL of ascitic fluid required for detectable ascites
• anorexia, nausea, early satiety, heartburn
• protruding flanks
• fluid wave
• shifting dullness (> 1.5 liters of ascitic fluid)
• puddle sign
• severe ascites
  • abdominal distension
  • shortness of breath

Laboratory

• general
  • complete blood count (CBC)
  • liver function tests
  • basic metabolic panel
  • serum amylase
  • serum triglycerides
  • serum BNP may help distinguish heart failure from cirrhosis as a cause of new-onset ascites
• paracentesis (see ascitic fluid analysis)
  • indications
    • all patients with new onset ascites
    • all patients with cirrhosis admitted to hospital
    • paracentesis takes priority over upper GI endoscopy if no GI bleeding
      • early diagnostic paracentesis within 12-24 hours is associated with lower in-hospital mortality, shorter hospital length of stay, & less acute kidney injury
  • tests
    • cell count
    • differential total protein & albumin (to enable calculation of serum albumin - ascites albumin gradient
    • gram stain, culture & sensitivity
    • acid fast stain, culture for Mycobacterium tuberculosis
    • cytology
    • specific gravity
    • serum amylase, serum triglycerides, serum bilirubin
  • transudates
    • clear or straw-colored fluid
    • [[[A13149|serum albumin]]] - [ascites albumin] >= 1.1 g/dL
      • protein in peritoneal fluid < 1.5 g/dL may indicate need for prophylaxis for spontaneous bacterial peritonitis
      • ascitic fluid protein > 2.5 g/dL suggests right heart disease or Budd Chiari syndrome
      • ascitic fluid protein < 2.5 g/dL suggests cirrhosis
    • [[[A13149|serum albumin]]] - [ascites albumin] < 1.1 g/dL &
      • ascitic fluid protein > 2.5 g/dL suggests infection, malignancy or pancreatic ascites
      • ascitic fluid protein < 2.5 g/dL suggests nephrotic syndrome or myxedema
    • specific gravity < 1.016
    • further ascites workup generally uneccessary
  • exudates
    • [[[A13149|serum albumin]]] - [ascites albumin] < 1.1 g/dL
    • chylous or turbid milky fluid with lymphatic obstruction
    • WBC > 500/mm3 or neutrophils > 250/mm3 indicates infection (spontaneous bacterial peritonitis)

Diagnostic procedures

• laparoscopy with biopsy of peritoneum & liver

Radiology

(as indicated)

• abdominal ultrasound (US) is imaging modality of choice
  • can detect > 100 mL of ascitic fluid
  • US of ovaries for suspected Meigs' syndrome
  • US of liver & spleen
• abdominal CT
• liver-spleen scan

Complications

• massive ascites may result in abdominal compartment syndrome

Differential diagnosis

• ovarian cyst
• pancreatic cyst
• bladder distension
• neoplasm

Management

• minimal ascites detected only by ultrasound does not require treatment
• moderate ascites
  • salt restriction (< 2 g of Na+/day)
  • bedrest
  • spironolactone (Aldactone) with furosemide
    • start 100 mg QD
    • increase by 100 mg QD up to 600 mg QD
    • goal is loss of 0.5-1 kg/day (0.5-1 liter/day)
  • furosemide (Lasix) 40 mg QD
• paracentesis
  • large volume ascites
  • all patients with new-onset ascites & all patients with cirrhosis & pre-existing ascites admitted to the hospital
  • removal of up to 5 liters of fluid is safe
  • administration of albumin if > 5 L of ascitic fluid removed
    • amount of albumin = 6-8 g/L of ascitic fluid removed
  • albumin may be appropriate if lesser amounts of ascitic fluid removed
• fluid restriction for hyponatremia (1.5-2 L/day)
• monitor blood pressure with portal hypertension
  • decrease or discontinue antihypertensives, especially ACE inhibitors, ARBs
• discontinue NSAIDs
• ascites resistant to diuretic therapy
  • discontinue diuretics
• presumptive bacterial peritonitis
  • peritoneal fluid neutrophils > 250/uL regardless of symptoms
  • serum creatinine > 1.0 mg/dL, serum urea nitrogen > 30 mg/dL, or serum bilirubin (total) > 4.0 mg/dL
  • 3rd generation cephalosporin
    • coverage for gram-negative coliform & Streptococcus
  • consider IV albumin infusion
    • 1.5 g/kg on day 1, followed by 1 g/kg on day 3
    • albumin should not be given to patients with uncomplicated ascites
  • prophylaxis
    • daily norfloxacin or ciprofloxacin for all patients who recover
    • ascites & GI hemorrhage: IV ceftriaxone for as long as 7 days
    • high-risk patients with cirrhosis & ascites may not benefit from antibiotic prophylaxis
• acute kidney injury
  • albumin is the volume expander of choice
• surgery
  • peritoneovenous (LeVeen) shunt
    • fewer hospital admissions for management of ascites relative to therapeutic paracentesis, but no difference in survival
  • transjugular intrahepatic portosystemic shunts (TIPS)
  • liver transplantation

More general terms

• sign/symptom

More specific terms

• pancreatic ascites

Additional terms

• ascitic fluid analysis
• paracentesis