Ascites diagnosis and management

Ascites diagnosis and management

Ascites diagnosis and management

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Pathophysiology - How Fluid Builds Up

  • The core driver is portal hypertension, which triggers splanchnic vasodilation via nitric oxide (NO) release. This pooling of blood in the gut circulation ↓ the effective arterial blood volume.
  • The kidneys perceive this "underfilling" and activate the Renin-Angiotensin-Aldosterone System (RAAS).
  • RAAS drives aggressive sodium and water retention, leading to total body fluid overload that manifests as ascites.

⭐ Splanchnic vasodilation, mediated by nitric oxide, is the primary driver that initiates sodium and water retention by the kidneys.

Diagnosis & SAAG - Tapping the Abdomen

  • Physical Exam: Suspect with abdominal distension. Key signs include shifting dullness and a positive fluid wave test. Ultrasound is the most sensitive method to confirm ascites.
  • Diagnostic Paracentesis (Abdominal Tap): Essential first step for new-onset ascites.
    • Fluid Analysis:
      • Cell count & differential: PMN > 250/mm³ suggests Spontaneous Bacterial Peritonitis (SBP).
      • Albumin & Total Protein: Crucial for SAAG calculation.
      • Culture: In blood culture bottles to improve yield.
  • Serum-Ascites Albumin Gradient (SAAG):
    • $SAAG = (Serum Albumin) - (Ascitic Fluid Albumin)$
    • SAAG > 1.1 g/dL: High gradient, indicates portal hypertension (e.g., cirrhosis, heart failure).
    • SAAG < 1.1 g/dL: Low gradient, suggests other causes (e.g., malignancy, pancreatitis).

⭐ The Serum-Ascites Albumin Gradient (SAAG) is the most useful single test for differentiating ascites caused by portal hypertension from other causes, with an accuracy of about 97%.

Management - Drain and Diurese

  • Initial Therapy: First-line management combines sodium restriction (<2 g/day) with diuretics.
  • Diuretic Regimen:
    • Start with oral Spironolactone and Furosemide.
    • 📌 Begin with a 100mg Spironolactone to 40mg Furosemide ratio to maintain normokalemia.
  • Tense/Refractory Ascites: Perform Large-Volume Paracentesis (LVP).
    • For removal >5L, infuse 6-8 g of IV albumin per liter removed.

⭐ Administering intravenous albumin after large-volume paracentesis (>5L) is crucial to prevent post-paracentesis circulatory dysfunction (PCD), characterized by rapid reaccumulation of ascites and renal impairment.

SBP - A Deadly Complication

  • Pathophysiology: Infection of ascitic fluid without an intra-abdominal source.
  • Symptoms: Fever, abdominal pain, altered mental status (can be subtle).
  • Diagnosis: Requires paracentesis.
    • Ascitic fluid PMN count ≥ 250 cells/mm³.
  • Treatment: Empiric 3rd-generation cephalosporins (e.g., Cefotaxime, Ceftriaxone).

Prophylaxis: Patients with a prior SBP episode, or ascitic fluid protein <1.5 g/dL with advanced liver failure, require long-term prophylaxis with fluoroquinolones (e.g., norfloxacin).

High‑Yield Points - ⚡ Biggest Takeaways

  • A SAAG (Serum-Ascites Albumin Gradient) ≥ 1.1 g/dL indicates portal hypertension; < 1.1 suggests other causes.
  • First-line treatment is sodium restriction and dual diuretics (spironolactone and furosemide, 100:40 ratio).
  • Suspect SBP with fever/pain; diagnose with ascitic fluid PMN count ≥ 250/mm³.
  • Treat SBP empirically with a third-generation cephalosporin (e.g., cefotaxime).
  • Large-volume paracentesis (>5L) requires IV albumin to prevent circulatory dysfunction.
  • Refractory ascites may necessitate TIPS or liver transplantation.

Practice Questions: Ascites diagnosis and management

Test your understanding with these related questions

A 42-year-old man with chronic hepatitis C is admitted to the hospital because of jaundice and abdominal distention. He is diagnosed with decompensated liver cirrhosis, and treatment with diuretics is begun. Two days after admission, he develops abdominal pain and fever. Physical examination shows tense ascites and diffuse abdominal tenderness. Paracentesis yields cloudy fluid with elevated polymorphonuclear (PMN) leukocyte count. A drug with which of the following mechanisms is most appropriate for this patient's condition?

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Flashcards: Ascites diagnosis and management

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Hepatic encephalopathy may be triggered by decreased NH3 removal, such as _____ failure

TAP TO REVEAL ANSWER

Hepatic encephalopathy may be triggered by decreased NH3 removal, such as _____ failure

renal

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