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Ascites, Pediatric

Basics

Description

- Cirrhotic ascites results from three pathophysiologic process: - Portal hypertension - Vasodilation: mediated predominantly by nitric oxide - Hyperaldosteronism: Decreased effective volume sensed by the kidneys stimulate the renin-angiotensin-aldosterone system, leading to increased sympathetic activity and antidiuretic hormone secretion.

- Noncirrhotic ascites can be the result of the following: - Proteinaceous material produced by malignant cells or by inflammation of visceral and/or parietal peritoneum: peritoneal carcinomatosis, tuberculous ascites - Obstruction of lymphatic flow by mass, tumor, or external pressure - Impaired portal flow: right-sided heart failure, Budd-Chiari syndrome, portal venous malformations - Decreased effective arterial blood volume: heart failure - Decreased oncotic pressure/ hypoalbuminemia: nephrotic syndrome, protein-losing enteropathy, severe malnutrition - Primary (congenital) abnormalities of the lymphatics, metabolic disorders (lysosomal storage diseases including sialidosis, Wolman disease, GM1 gangliosidosis, Gaucher disease, and Niemann-Pick type C) - Rupture of intra-abdominal viscus or peritoneal/mesenteric cyst, bowel perforation, ureteral rupture

- Ascitic fluid analysis is essential: - Cell count and differential - Albumin, total protein - Culture, Gram stain - Glucose (low in infection) - Lactate dehydrogenase concentration (high in infection, bowel perforation, or tumor) - Other optional tests include amylase (high in perforated viscus or pancreatitis), triglycerides (high in chylous ascites), and cytology (peritoneal carcinomatosis).

- The management of the ascites should be directed toward the underlying etiology. - Benefits of treatment of ascites should always be weighed against risks and complications of treatment. - Mobilization of cirrhotic ascitic fluid is best accomplished by creating a negative sodium balance and then maintaining the balance. - In patients with cirrhosis, causes of decompensation should be sought, such as sodium and fluid overload, infection, esophageal hemorrhage, spontaneous bacterial peritonitis. - In adults, dietary sodium intake is restricted to 44-88 mEq (1-2 g/24 h) or approximately 17-35 mEq (0.4-0.8 g) per thousand calories. - In pediatrics, restricting dietary sodium intake is recommended: diet with no extra salt to a maximum 2 mEq/kg/24 h (to be balanced against palatability of food and nutritional needs). - Water is only restricted in patients with profound hyponatremia (<125 mEq/L): 50-75% of maintenance requirements. - Goal of diuretic therapy is reduction of bodyweight by 0.5-1% daily until ascites is resolved. - Spironolactone (PO) - Most effective single diuretic, as it counteracts the hyperaldosteronism present in cirrhotic ascites - Acts on the distal collecting system, hence, inhibits reabsorption of 2% of filtered sodium - Bioactive metabolites have long half-lives, hence, need >5 days to achieve steady state. - Start at 2-3 mg/kg/24 h as a single morning (max 100 mg initial dose). In adults, typical starting dose is up to 100 mg/24 h and can be increased to max 400 mg/24 h. - Most effective in combination with furosemide

  • Ascites is defined as a pathologic accumulation of intraperitoneal fluid.
  • Peritoneal fluid formation is a dynamic process of production and absorption.
  • In children, ascites is usually the result of liver or renal disease.
  • In adults, ascites is most often due to portal hypertension from cirrhosis.
  • Ascites is the most common of the three major complications of cirrhosis; the other two complications of cirrhosis are hepatic encephalopathy and variceal hemorrhage.

Pathophysiology

  • Normal circulationBlood enters the liver from the hepatic artery and portal vein, perfuses the hepatic sinusoids, and exits the liver via the hepatic veins.Hepatic lymph, formed by the filtration of sinusoidal plasma into the space of Disse, drains from the liver via the transdiaphragmatic lymphatic vessels to the thoracic duct.Hepatic lymph is isosmotic to plasma, as the sinusoidal endothelium is highly permeable to albumin.In the intestine, the mesenteric capillary membrane is impermeable to albumin. The osmotic gradient favors the return of interstitial fluid/lymph into the capillary.Intestinal lymph from regional lymphatics combines with hepatic lymph in the thoracic duct.
  • Portal hypertensionAscitic fluid production is due to a net transfer of fluid that exceeds the drainage capacity of the lymphatics.
  • Cirrhotic ascites results from three pathophysiologic process:Portal hypertensionVasodilation: mediated predominantly by nitric oxideHyperaldosteronism: Decreased effective volume sensed by the kidneys stimulate the renin-angiotensin-aldosterone system, leading to increased sympathetic activity and antidiuretic hormone secretion.
  • Noncirrhotic ascites can be the result of the following:Proteinaceous material produced by malignant cells or by inflammation of visceral and/or parietal peritoneum: peritoneal carcinomatosis, tuberculous ascitesObstruction of lymphatic flow by mass, tumor, or external pressureImpaired portal flow: right-sided heart failure, Budd-Chiari syndrome, portal venous malformationsDecreased effective arterial blood volume: heart failureDecreased oncotic pressure/ hypoalbuminemia: nephrotic syndrome, protein-losing enteropathy, severe malnutritionPrimary (congenital) abnormalities of the lymphatics, metabolic disorders (lysosomal storage diseases including sialidosis, Wolman disease, GM1 gangliosidosis, Gaucher disease, and Niemann-Pick type C)Rupture of intra-abdominal viscus or peritoneal/mesenteric cyst, bowel perforation, ureteral rupture

Etiology

Accumulation of fluid occurs with the following:

  • Inflammatory conditions (e.g., mesenteric adenitis, tuberculosis, pancreatitis, secondary to inflammation of visceral, and/or parietal peritoneum)
  • Portal hypertension or obstruction of portal vein flow and/or lymphatic flow by mass, tumor, or external pressure; tumors of abdominal viscera, retroperitoneum, thorax, or mediastinum (often characterized by chylous ascites)
  • Infectious processes: abscess, tuberculosis, Chlamydia infection, schistosomiasis
  • Gastrointestinal: infarcted bowel/perforation, pancreatitis, ruptured pancreatic duct, parenchymal liver disease
  • Gynecologic: ovarian tumors, torsion, or rupture
  • Renal: nephrotic syndrome, obstructive uropathy, perforated urinary tract, peritoneal dialysis
  • Cardiac: CHF, constrictive pericarditis, inferior vena cava web
  • Neoplastic: lymphoma, neuroblastoma
  • Miscellaneous: systemic lupus erythematous, eosinophilic ascites, chylous ascites, hypothyroidism, ventriculoperitoneal shunt

Diagnosis

History

  • The etiology for acute decompensation in hepatocellular function (e.g., massive bleeding, sepsis, superimposed infections) should be investigated.
  • Weight gain
  • Use of umbilical catheters in newborn period (increased risk of portal vein thrombosis)
  • Evidence of chronic liver disease
  • Respiratory distress
  • Exposure to hepatotoxins
  • Developmental delay or growth failure suggestive of metabolic disease

Physical Exam

  • Vital signs:Increased heart rate (increased cardiac output)Lower blood pressure seen in cirrhotics
  • General appearance: cachexia
  • Abdominal examProtuberant abdomen, bulging flanks (fluid wave or shifting dullness)Caput medusae, umbilical hernia,Dullness to percussionPeritoneal signsAbdominal painSplenomegaly
  • Auscultation of the pericardium: pericardial friction rub (pericarditis), cor pulmonale
  • Neurologic exam: hepatic encephalopathy
  • SkinJaundiceSpider angiomaPalmar erythemaScratch marksStriaeXanthomas
  • Extremities

Diagnostic Evaluation

Laboratory

  • Complete blood count
  • Electrolytes
  • Liver test: transaminases, prothrombin time/international normalized ratio, total protein, albumin, total and fractionated bilirubin
  • Amylase and lipase (to exclude pancreatitis)
  • Creatinine and blood urea nitrogen
  • Fluid cultures: blood, urine, ascitic fluid
  • Urinalysis
  • Specific testing for etiologies of ascites from chronic liver disease and other causes as deemed appropriate

Imaging

  • Ultrasound of the abdomen with Doppler studyStudy of choice to differentiate between free and loculated fluid collection and the presence of intra-abdominal massesCan evaluate patency of hepatic and portal vasculature and directionality of flow
  • Plain radiography (centralized bowel loops)
  • Abdominal computed axial tomography
  • Abdominal magnetic resonance imaging

Abdominal Paracentesis

  • Ascitic fluid analysis is essential:Cell count and differentialAlbumin, total proteinCulture, Gram stainGlucose (low in infection)Lactate dehydrogenase concentration (high in infection, bowel perforation, or tumor)Other optional tests include amylase (high in perforated viscus or pancreatitis), triglycerides (high in chylous ascites), and cytology (peritoneal carcinomatosis).
  • Serum to ascites albumin gradient (SAAG)(Serum albumin) - (ascites albumin)Blood and ascitic fluid analysis should be obtained on same day.SAAG ≥1.1 g/dL suggests presence of portal hypertension.If SAAG <1.1 g/dL, suspect other causes.

Differential Diagnosis

  • Organomegaly: enlarged liver or spleen
  • Mesenteric cyst or ovarian cyst: does not have shifting dullness when position is changed
  • Bowel obstruction
  • Cancer
  • Heart failure
  • Nephrotic syndrome

Treatment

  • The management of the ascites should be directed toward the underlying etiology.
  • Benefits of treatment of ascites should always be weighed against risks and complications of treatment.
  • Mobilization of cirrhotic ascitic fluid is best accomplished by creating a negative sodium balance and then maintaining the balance.
  • In patients with cirrhosis, causes of decompensation should be sought, such as sodium and fluid overload, infection, esophageal hemorrhage, spontaneous bacterial peritonitis.
  • In adults, dietary sodium intake is restricted to 44-88 mEq (1-2 g/24 h) or approximately 17-35 mEq (0.4-0.8 g) per thousand calories.
  • In pediatrics, restricting dietary sodium intake is recommended: diet with no extra salt to a maximum 2 mEq/kg/24 h (to be balanced against palatability of food and nutritional needs).
  • Water is only restricted in patients with profound hyponatremia (<125 mEq/L): 50-75% of maintenance requirements.
  • Goal of diuretic therapy is reduction of bodyweight by 0.5-1% daily until ascites is resolved.
  • Spironolactone (PO)Most effective single diuretic, as it counteracts the hyperaldosteronism present in cirrhotic ascitesActs on the distal collecting system, hence, inhibits reabsorption of 2% of filtered sodiumBioactive metabolites have long half-lives, hence, need >5 days to achieve steady state.Start at 2-3 mg/kg/24 h as a single morning (max 100 mg initial dose). In adults, typical starting dose is up to 100 mg/24 h and can be increased to max 400 mg/24 h.Most effective in combination with furosemide
  • Adequacy of spironolactone therapy can be monitored with urinary sodium excretion (desired >50 mEq/L). If no response, furosemide is added.
  • Furosemide (PO)Loop diuretic: can increase sodium excretion by 30%Start at 1 mg/kg (max initial dose 40 mg), may increase every few days if needed.Adults maintain ratio of 100 mg of spironolactone to 40 mg of furosemide to maintain eukalemia (max 400 mg spironolactone to 160 mg of furosemide daily)
  • When diuretics are used, urine output and serum electrolytes should be closely monitored to prevent prerenal azotemia and decreased effective blood flow to the kidneys.
  • Albumin: Supplementation may aid fluid mobilization if albumin is <2.5 g/dL (use 1 g/kg of 25% albumin until level >2.5 g/dL).
  • Refractory ascites: Diuretic-refractory ascites derives from a lack of response to dietary sodium restriction and maximal diuretic therapy. Treatment options are the following:Therapeutic abdominal paracentesis (large-volume paracentesis) is used in adults with refractory ascites.In children, this approach is used to relieve respiratory distress or other sequelae of rapidly increasing intra-abdominal pressure.Paracentesis of volumes >1 L should be accompanied by IV infusion of 25% albumin during the procedure.Transjugular intrahepatic portosystemic shunting may be valuable in cases where portal hypertension is felt to be the underlying etiology of ascitic accumulation.Orthotopic liver transplantation is the only curative therapy for refractory ascites from liver disease and the only definitive treatment that has been shown to improve survival.
  • When diuretics are used, urine output and serum electrolytes should be closely monitored to prevent prerenal azotemia and decreased effective blood flow to the kidneys.

Alert

  • Ultrasonography should be the initial diagnostic imaging of choice for evaluation of ascites.
  • With congenital ascites, evaluate for lysosomal storage diseases.
  • Diagnostic paracentesis is crucial in the evaluation of new-onset ascites.
  • Calculate SAAG to differentiate between portal hypertension and other causes.
  • In patients with liver disease and new-onset ascites, evaluate for etiologies to explain acute decompensation.

Prognosis

  • Development of ascites in the setting of cirrhosis is a landmark in the natural history of cirrhosis: 15% of adult patients succumb in 1 year and 44% in 5 years.
  • Liver transplantation dramatically improves survival.
  • Prognosis depends on etiology of ascites: nephrotic syndrome (ascites will regress as proteinuria clears), infection, hepatic decompensation (prognosis improves if able to reverse cause of liver injury).

Complications

  • Spontaneous bacterial peritonitis (SBP)Spontaneous ascitic fluid infection: Infection of the peritoneal fluid may occur in the absence of secondary cause (e.g., bowel perforation or intra-abdominal abscess).Fever, irritability, abdominal tenderness, and distention are common signs, vomiting and diarrhea may occur.Abdominal paracentesis must be performed and ascitic fluid must be analyzed before a confident diagnosis of ascitic fluid infection can be made. The blood culture bottle should be injected with peritoneal fluid at the bedside in order to increase the culture yield.Diagnosis: ascitic fluid absolute polymorphonuclear leukocytes ≥250 cells/mm3 without evidence of an intra-abdominal processBacterial organisms commonly identified are the following: Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, enterococci, and Haemophilus influenzae.Broad-spectrum antibiotics with gram-negative coverage such as third generation cephalosporin can be used until identification of bacterial pathogen allows narrower coverage.Prophylaxis for recurrent SBP has been recommended in certain situations.
  • Other complications:Respiratory distress from decreased lung volume and diaphragmatic limitation: hepatic hydrothorax (large symptomatic pleural effusion that occurs in a cirrhotic patient in the absence of primary cardiopulmonary disease), abdominal wall hernias with rupture, tense ascites with leakage (especially after paracentesis)Conservative management consists of appropriate initial therapy for most of these except hernia rupture, which requires surgical reduction.

Additional Reading

  • European Association for the Study of the Liver. EASL clinical practice guideline on the management of ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome in cirrhosis. J Hepatol. 2010,53(3):397-417. [View Abstract]
  • Griefer MJ, Murray KF, Colleti RB. Pathophysiology, diagnosis, and management of pediatric ascites. J Pediatr Gastroenterol Nutr. 2011;52(5):503-513. [View Abstract]
  • Hou W, Sanyal AJ. Ascites: diagnosis and management. Med Clin North Am. 2009;93(4):801-817. [View Abstract]
  • Runyon BA. Management of adult patients with ascites due to cirrhosis: update 2012. Hepatology. 2013(6):2087-2107. [View Abstract]

Codes

ICD09

  • 789.59 Other ascites
  • 789.51 Malignant ascites
  • 014.00 Tuberculous peritonitis, unspecified

ICD10

  • R18.8 Other ascites
  • R18.0 Malignant ascites
  • A18.31 Tuberculous peritonitis

SNOMED

  • 389026000 Ascites (disorder)
  • 236005001 Malignant ascites (disorder)
  • 236004002 Hepatic ascites (disorder)
  • 4501007 Tuberculous ascites (disorder)

FAQ

  • Q: What etiologies are likely in cases of congenital ascites?
  • A: Lysosomal storage disorders and/or other metabolic diseases should be excluded. If hepatic function is impaired, causes of neonatal liver failure should also be investigated.
  • Q: What is the best test to discriminate the type of ascites?
  • A: Analysis of the peritoneal fluid collected by abdominal paracentesis is required for this purpose. The SAAG is helpful to discriminate ascites due to portal hypertension from other etiologies.
  • Q: Where does the word "ascites" come from?
  • A: It is thought that the word ascites is derived from the Greek word "askos" which refers to a container of wine or a wineskin.