Causes of Tense Ascites in Children
In children, tense ascites most commonly results from cirrhosis due to biliary atresia, primary sclerosing cholangitis, autoimmune hepatitis, and other genetic/metabolic liver disorders, though rapid accumulation should immediately raise concern for portal or hepatic vein thrombosis or spontaneous bacterial peritonitis. 1
Primary Etiologies by Age Group
Neonates and Infants
- Cirrhosis from congenital conditions including biliary atresia, congenital infections (TORCH), mitochondrial disorders, and tyrosinemia 1
- Surgical emergencies such as intestinal atresia, malrotation with midgut volvulus, or bowel perforation causing peritoneal fluid accumulation 2
Older Children
- Biliary atresia remains the leading cause of cirrhotic ascites in the pediatric population 1
- Primary sclerosing cholangitis, particularly when associated with inflammatory bowel disease 1
- Autoimmune hepatitis with progression to cirrhosis 1
- Genetic cholestatic disorders including progressive familial intrahepatic cholestasis and bile salt excretory pump disease 1
- Wilson disease and alpha-1 antitrypsin deficiency 1
- Metabolic disorders affecting liver function 1
Pathophysiology of Tense Ascites
The development of tense ascites in cirrhotic children involves multiple mechanisms:
- Portal hypertension is the primary driver, creating increased hydrostatic pressure 1, 3
- Peripheral arterial vasodilation leads to inappropriate sodium and fluid retention 3, 4
- Hyperaldosteronism perpetuates sodium retention 1
- Hypoalbuminemia reduces oncotic pressure, facilitating fluid extravasation 1, 3
Critical Red Flags Requiring Urgent Evaluation
Rapid accumulation of ascites demands immediate investigation for life-threatening complications:
- Portal or hepatic vein thrombosis (Budd-Chiari syndrome) 1
- Spontaneous bacterial peritonitis with ascitic fluid neutrophil count ≥250 cells/mm³ 1, 5, 4
- Hepatic decompensation with worsening liver synthetic function 1
Non-Cirrhotic Causes
While less common, tense ascites can occur without cirrhosis:
- Acute viral hepatitis with severe hepatocellular injury 5
- Acute liver failure from various etiologies 5
- Extrahepatic portal venous obstruction (portal vein thrombosis) 5
- Cardiac causes including congestive heart failure and constrictive pericarditis 3
- Renal disorders causing nephrotic syndrome 3
- Malignancy with peritoneal carcinomatosis (rare in children) 3
- Infectious causes including tuberculous peritonitis 3
Diagnostic Approach
Ultrasonography is the first-line imaging modality to confirm ascites, differentiate from organomegaly, and identify venous thromboses or other structural abnormalities 1, 6
Diagnostic paracentesis is indicated when:
- The cause of ascites is unclear 1, 6
- Spontaneous bacterial peritonitis is suspected 1, 6
- New-onset ascites is present 5
- At the beginning of each hospital admission 5, 4
Essential ascitic fluid analysis includes:
- Cell count with differential (neutrophil count ≥250/mm³ indicates infection) 5, 4
- Serum-ascites albumin gradient (SAAG ≥1.1 g/dL confirms portal hypertension) 3, 5, 4
- Total protein and albumin levels 5, 4
- Bacterial culture 5, 4
Clinical Impact of Tense Ascites
Tense ascites creates multiple life-threatening complications:
- Respiratory compromise from diaphragmatic elevation and reduced lung expansion 1, 6
- Renal perfusion impairment potentially precipitating hepatorenal syndrome 1
- Increased infection risk due to bacterial translocation 1
- Severe quality of life impairment from abdominal discomfort and functional limitation 1
Common Pitfalls
- Mistaking organomegaly or bowel vascular congestion for ascites based on abdominal distension alone; physical examination for "ballotable fluid" between the abdominal wall and liver surface is more reliable 1
- Delaying paracentesis in children with rapid ascites accumulation, missing treatable causes like infection or vascular thrombosis 1
- Failing to recognize neonatal surgical emergencies presenting with abdominal distension that may mimic ascites 2