Overview

Definition and epidemiology

• Accumulation of fluid within the peritoneal cavity

• Associated with increased mortality in cirrhotic patients
  • Episodic ascites → 50% 3-year mortality
  • Refractory ascites → 50% 1-year mortality
• 5% of patients will have more than one cause.

Etiology

• Portal hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • Cirrhosis is the most common cause (80% of cases).
  • Hepatitis (without cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis)
  • Hepatic veno-occlusive disease ( Budd-Chiari syndrome Budd-Chiari syndrome Budd-Chiari syndrome is a condition resulting from the interruption of the normal outflow of blood from the liver. The primary type arises from a venous process (affecting the hepatic veins or inferior vena cava) such as thrombosis, but can also be from a lesion compressing or invading the veins (secondary type). The patient typically presents with hepatomegaly, ascites, and abdominal discomfort. Budd-Chiari Syndrome)
  • Heart failure
  • Constrictive pericarditis Pericarditis Pericarditis is an inflammation of the pericardium, often with fluid accumulation. It can be caused by infection (often viral), myocardial infarction, drugs, malignancies, metabolic disorders, autoimmune disorders, or trauma. Acute, subacute, and chronic forms exist. Pericarditis
  • Hemodialysis
• Hypoalbuminemia
  • Nephrotic syndrome Nephrotic syndrome Nephrotic syndrome is characterized by severe proteinuria, hypoalbuminemia, and peripheral edema. In contrast, the nephritic syndromes present with hematuria, variable loss of renal function, and hypertension, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephrotic Syndrome
  • Enteropathy
  • Malnutrition Malnutrition Malnutrition is a clinical state caused by an imbalance or deficiency of calories and/or micronutrients and macronutrients. The 2 main manifestations of acute severe malnutrition are marasmus (total caloric insufficiency) and kwashiorkor (protein malnutrition with characteristic edema). Malnutrition in children in resource-limited countries
• Peritoneal disease
  • Malignancy
  • Infection 
  • Peritoneal dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Overview and Types of Dialysis
• Other
  • Chylous ascites
  • Pancreatic duct injury
  • Myxedema
  • Hemoperitoneum
  • Vasculitis

Pathophysiology

Ascites is caused by an osmotic and/or hydrostatic pressure imbalance often secondary to:

• Portal hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension (most common)
• Non- portal hypertension Portal hypertension Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Portal Hypertension
  • Hypoalbuminemia
  • Malignancy 
  • Infection

Portal hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension-related ascites:

• ↑ Pressure in the portal vein → ↑ hydrostatic pressure in the downstream hepatic vessels → fluid shift from the intravascular space to the peritoneal cavity
• ↑ Splanchnic vasodilation and blood pooling → ↓ arterial volume → ↓ renal blood flow → renin-angiotensin-aldosterone system (RAAS) activation → sodium and water retention

Non- portal hypertension Portal hypertension Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Portal Hypertension–related ascites:

• Hypoalbuminemia: ↓ oncotic pressure in the vessels → ↓ intravascular osmotic gradient → fluid shift from the intravascular space to the peritoneal cavity
• Malignancy: blockage of lymphatic channels and ↑ vascular permeability
• Infection: ↑ vascular permeability

Clinical Presentation

Symptoms

• Abdominal distension 
• Weight gain
• Abdominal discomfort
• Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
• Early satiety
• Time course of symptoms will vary depending on the etiology.

Physical exam

• Abdominal distension: may be associated with umbilical eversion
• Shifting dullness 
  • Change of resonance (from dull to tympanic) when patient changes from supine to lateral decubitus position
  • Approximately 1.5 L of fluid must be present to be detected by this method.
• Fluid wave test 
  • Wave produced by tapping 1 side of the abdomen in a patient in the supine position 
  • This fluid wave will be transmitted to the other side of the abdomen via the ascitic fluid.
• Evidence for the underlying etiology:
  • Liver disease:
    • Hepatosplenomegaly
    • Jaundice and scleral icterus
    • Spider angiomata
    • Palmar erythema
    • Caput medusae
  • Heart failure:
    • Crackles
    • Jugular venous distension
    • Peripheral edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • Malignancy:
    • Weight loss
    • Virchow’s node (enlarged left-sided supraclavicular lymph node)

Management

Conservative management

• Sodium restriction (< 2 g/day)
• Treat the underlying etiology.
• Diuretic therapy
  • Furosemide
  • Spironolactone

Invasive management

• Therapeutic paracentesis
  • Rapid symptom relief
  • Used if ascites is refractory to conservative measures
  • Albumin infusion is needed if > 5 L of ascites is removed.
    • Prevents large intravascular fluid shifts, kidney injury, and electrolyte abnormalities
• Transjugular intrahepatic portosystemic shunt (TIPS)
  • Creates a connection between the portal and systemic circulations to reduce portal hypertension Portal hypertension Portal hypertension is increased pressure in the portal venous system. This increased pressure can lead to splanchnic vasodilation, collateral blood flow through portosystemic anastomoses, and increased hydrostatic pressure. There are a number of etiologies, including cirrhosis, right-sided congestive heart failure, schistosomiasis, portal vein thrombosis, hepatitis, and Budd-Chiari syndrome. Portal Hypertension
  • For patients with ascites refractory to the above measures
• Consideration for liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver transplantation for cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis patients with refractory ascites

Management algorithm

The figure below summarizes how to approach treatment in a patient with ascites:

Complications

Spontaneous bacterial peritonitis

• Common and potentially fatal bacterial infection of ascitic fluid
• Symptoms:
  • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
  • Abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain 
  • Hypotension Hypotension Hypotension is defined as low blood pressure, specifically < 90/60 mm Hg, and is most commonly a physiologic response. Hypotension may be mild, serious, or life threatening, depending on the cause. Hypotension
  • Encephalopathy 
• Diagnosis:
  • Paracentesis with PMN > 250 cells/mm³ in the ascitic fluid
  • Most often caused by aerobic gram-negative organisms (Escherichia coli)
• Treatment:
  • Intravenous (IV) cefotaxime or ceftriaxone 
  • IV albumin decreases mortality by lowering the risk of acute renal failure.
• Prophylaxis is considered in patients with:
  • Gastrointestinal (GI) bleed: ceftriaxone or norfloxacin
  • Prior episodes of SBP: long-term therapy of norfloxacin or trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim-sulfamethoxazole (TMP-SMX)

Hepatic hydrothorax

• Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion development in cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic parenchymal necrosis and scarring (fibrosis) most commonly due to hepatitis C infection and alcoholic liver disease. Patients may present with jaundice, ascites, and hepatosplenomegaly. Cirrhosis can also cause complications such as hepatic encephalopathy, portal hypertension, portal vein thrombosis, and hepatorenal syndrome. Cirrhosis patients
• Likely due to the passage of ascites into the pleural space through defects in the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm
• Symptoms:
  • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
  • Non-productive cough
  • Pleuritic chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
• Diagnosis:
  • Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion may be seen on chest X-ray.
  • Thoracentesis can confirm the diagnosis.
    • Transudate
    • Low PMN count rules out spontaneous bacterial empyema.
    • Rule out other causes.
• Treatment:
  • Similar to ascites (sodium restriction, diuretics)
  • Refractory hydrothorax
    • Thoracentesis
    • TIPS
    • Liver transplant consideration

Umbilical hernia

• Soft bulge near the umbilicus 
  • Due to protrusion of bowel or fatty tissue through the abdominal wall 
  • Results from increased abdominal pressure secondary to ascites
• Occurs in 20% of patients with ascites
• Typically asymptomatic
• Incarceration should be considered if the hernia becomes painful and is unable to be reduced.
• Treatment
  • Management of ascites
  • Surgical repair

Risks associated with repeated paracentesis

• Hypovolemia
• Acute kidney injury Acute Kidney Injury Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury 
• Bleeding
• Bowel perforation
• Electrolyte imbalances
• Infection

Differential Diagnosis

• Obesity Obesity Obesity is a condition associated with excess body weight, specifically with the deposition of excessive adipose tissue. Obesity is considered a global epidemic. Major influences come from the western diet and sedentary lifestyles, but the exact mechanisms likely include a mixture of genetic and environmental factors. Obesity: abnormal and excess fat deposition, which presents a risk to the patient’s health. Locations of fat accumulation can vary from person to person. Abdominal obesity can give the appearance of abdominal distension. Calculating the patient’s body mass index (BMI) and evaluating the history can give clues to the diagnosis. In addition, imaging will not demonstrate ascites. Treatment focuses on lifestyle modifications.
• Ovarian cyst: most commonly presents as an asymptomatic mass in women. These cysts may be physiologic, malignant, or benign. Patients may have pelvic pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, bloating, and abdominal distension (if significantly enlarged). Diagnosis is with pelvic exam and ultrasound, which will differentiate an ovarian cyst from ascites. Treatment depends on the type of cyst; may require surgery if the cyst is large or there is concern for malignancy. 
• Small bowel obstruction Small Bowel Obstruction Small bowel obstruction (SBO) is an interruption of the flow of the intraluminal contents through the small intestine, and is classified as mechanical (due to physical blockage) or functional (due to disruption of normal motility). The most common cause of SBO in the Western countries is post-surgical adhesions. Small bowel obstruction typically presents with nausea, vomiting, abdominal pain, distention, constipation, and/or obstipation. Small Bowel Obstruction: disruption of the normal flow of intraluminal contents in the bowel; may be functional or mechanical. Patients may have abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, distension, and vomiting. Exam will show tympany to percussion instead of the shifting dullness in ascites. Diagnosis is by clinical history or abdominal X-ray, which will show dilated bowel loops and air-fluid levels. Treatment includes nasogastric decompression, intravenous fluids Intravenous Fluids Intravenous fluids are one of the most common interventions administered in medicine to approximate physiologic bodily fluids. Intravenous fluids are divided into 2 categories: crystalloid and colloid solutions. Intravenous fluids have a wide variety of indications, including intravascular volume expansion, electrolyte manipulation, and maintenance fluids. Intravenous Fluids, and, sometimes, surgery.
• Kwashiorkor: a type of severe acute malnutrition most commonly seen in children of resource-limited countries (though it can also occur in older adults). Exam findings include abdominal distension, anasarca, bradycardia, and hypotension. The history and evidence of severe wasting will point to the diagnosis and differentiate it from possible causes of ascites. Treatment includes nutritional support and close monitoring for re-feeding complications.
• Pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care: period of fetal development in a woman’s uterus. Uterus expansion will increase abdominal size. Diagnosis is made through measurement of human chorionic gonadotropin (hCG) and confirmed with ultrasound, which differentiates it from ascites.