Approach to Child with Ascites

definition and pathophysiology

• Pathologic accumulation of fluid within peritoneal cavity.
• Results from increased hydrostatic and osmotic pressures within hepatic and mesenteric capillaries.
• Fluid transfer from blood vessels to lymphatics overcomes drainage capacity.
• Peripheral arterial vasodilation hypothesis: Portal hypertension causes splanchnic vasodilation, leading to decreased effective intravascular volume.
• Baroreceptors trigger renin-angiotensin-aldosterone (RAA) system and antidiuretic hormone release, driving renal sodium and water retention.
• Decreased plasma colloid osmotic pressure (hypoalbuminemia) further exacerbates fluid shift.

etiological classification

clinical evaluation

history

• Rapid weight gain, increasing abdominal girth, ankle edema.
• Neonatal umbilical catheterization (risk factor for portal vein thrombosis).
• History of gastrointestinal bleeding or unexplained splenomegaly.

physical examination

• Abdominal distension, bulging flanks, shifting dullness.
• Fluid thrill, puddle sign (dullness over umbilicus in prone position).
• Tense ascites associated with umbilical herniation.
• Liver disease stigmata: Jaundice, palmar erythema, spider angiomata, caput medusae (dilated abdominal collaterals).
• Cardiac evaluation: Markedly elevated jugular venous pressure indicates cardiac origin.

diagnostic investigations

imaging

• Abdominal ultrasound: Most sensitive modality for ascites detection.
• Differentiates ascites from obesity or pseudoascites (omental/ovarian cysts).
• Identifies portal hypertension signs: Splenomegaly, enlarged portal vein.
• Doppler evaluates hepatic vasculature flow and direction.

diagnostic paracentesis

• Indicated upon initial detection, hospitalization, or clinical deterioration (fever, pain).
• Ultrasound-guided tap recommended for loculated ascites.
• No contraindication for prolonged prothrombin time unless disseminated intravascular coagulation present.

Ascitic fluid analysis

management protocol

dietary modifications

• Sodium restriction: Mainstay of therapy. Limit to 1-2 mEq/kg/day for infants/children or "no salt added" diet.
• Fluid restriction: Rarely indicated unless severe hyponatremia (<125-130 mEq/L) present.
• High-protein, high-calorie diet improves serum albumin and oncotic pressure.

pharmacologic therapy

• Target optimal weight loss without intravascular volume depletion.
• Spironolactone: Aldosterone antagonist, first-line agent. Dose 2-5 mg/kg/day.
• Furosemide: Added for resistant ascites or to counteract spironolactone-induced hyperkalemia. Dose 0.5-2 mg/kg/day.
• Optimal diuretic ratio: 5 (spironolactone) to 2 (furosemide).

refractory ascites interventions

• Defined as ascites unresponsive to sodium restriction and maximal diuretic therapy.
• Large volume paracentesis: Performed for tense ascites causing respiratory distress or severe pain.
• Requires concurrent 20% albumin infusion (5 ml/kg) to prevent post-paracentesis circulatory dysfunction and rapid reaccumulation.
• Transjugular intrahepatic portosystemic shunting (TIPS): Diverts portal blood flow, decreases portal pressure. Used as bridge to transplant.
• Liver transplantation: Definitive treatment for ascites associated with end-stage liver disease, hypoalbuminemia, or recurrent SBP.

complications

spontaneous bacterial peritonitis (SBP)

• Spontaneous infection of ascitic fluid without intra-abdominal source.
• Pathogenesis: Bacterial translocation from gut to mesenteric lymph nodes, impaired immune clearance.
• Presentation: Fever, abdominal pain, unexplained clinical deterioration, encephalopathy.
• Diagnosis: Ascitic fluid PMN $\ge$ 250 cells/mm3.
• Treatment: Intravenous third-generation cephalosporins (e.g., cefotaxime, ceftriaxone) for 5-7 days.
• Prophylaxis: Long-term oral norfloxacin recommended after prior SBP episode.