Ascites: Definition and Pathophysiology

Definition and Etiology

• Ascites is the abnormal accumulation of fluid in the peritoneal cavity, the space surrounding the abdominal organs.
• This fluid buildup causes abdominal swelling and discomfort.
• Common causes include liver cirrhosis, heart failure, kidney disease, and cancer. Infections and pancreatitis can also contribute.

Pathophysiology

• The mechanisms behind ascites are complex and often multiple.
• Conditions like cirrhosis disrupt the balance between fluid retention and removal, changing protein and hormone activity.
• Portal hypertension, high blood pressure in veins draining the digestive tract, is a key factor in cirrhosis-related ascites. This increased pressure forces fluid from the blood into the abdomen.
• Renal dysfunction reduces the kidney's ability to filter excess fluid, worsening buildup.

Clinical Presentation

• Patients with ascites experience abdominal swelling, fullness, and discomfort.
• Shortness of breath can occur due to diaphragm pressure.
• Other symptoms vary based on the underlying cause, potentially including fatigue, nausea, and weight gain.
• Physical exams may reveal a distended abdomen, fluid wave, and shifting dullness.

Diagnosis

• Clinical evaluation is vital for ascites suspicion.
• Physical exam findings guide further testing.
• Abdominal ultrasound or CT scans confirm fluid buildup and assess the cause.
• Paracentesis, a needle insertion to remove fluid for analysis, confirms fluid properties and helps identify the cause (e.g., infection). It guides treatment.
• Lab tests (complete blood count, liver function tests, and kidney function tests) assess organ system function.

Treatment

• Treatment targets the underlying cause of ascites.
• Diuretics (spironolactone, furosemide) increase urination to reduce fluid retention.
• Dietary sodium restriction is crucial to reduce fluid overload.
• Paracentesis relieves severe ascites when diuretics are insufficient.
• Transjugular intrahepatic portosystemic shunt (TIPS) may be considered to reduce portal hypertension in some cases.
• Infections (e.g., spontaneous bacterial peritonitis) need prompt antibiotic therapy and support.

Complications

• Untreated or poorly managed ascites causes significant complications.
• Severe fluid buildup impairs breathing and other bodily functions.
• Spontaneous bacterial peritonitis (SBP) develops when ascites fluid becomes infected.
• Hepatorenal syndrome is declining kidney function linked to liver disease.
• Increased infection risk and poor nutrition increase morbidity and mortality.

Prognosis

• Ascites prognosis hinges on the underlying cause and liver disease severity.
• Patients with compensated liver disease, managed appropriately, typically have a better prognosis, with reduced symptoms and improved quality of life.
• Progression of underlying conditions worsens quality of life and can lead to serious health issues.