Ascites

Aschytes, that is, abdominal dropsy, came on the scene a century later, from the Latin ascites that was also originally Greek (askites [ασκίτης]) and literally meant “bag‐like dropsy,” from askós (ἀσκός), a leather bag or sheepskin (“wineskin”) used for carrying wine, water, and oil.[6]

Mild ascites is hard to notice, but severe ascites leads to abdominal distension. People with ascites generally will complain of progressive abdominal heaviness and pressure as well as shortness of breath due to mechanical impingement on the diaphragm.[7]

Ascites is detected with physical examination of the abdomen by visible bulging of the flanks in the reclining person ("flank bulging"), "shifting dullness" (difference in percussion note in the flanks that shifts when the person is turned on the side), or in massive ascites, with a "fluid thrill" or "fluid wave" (tapping or pushing on one side will generate a wave-like effect through the fluid that can be felt in the opposite side of the abdomen).

Other signs of ascites may be present due to its underlying cause. For instance, in portal hypertension (perhaps due to cirrhosis or fibrosis of the liver) people may also complain of leg swelling, bruising, gynecomastia, hematemesis, or mental changes due to encephalopathy. Those with ascites due to cancer (peritoneal carcinomatosis) may complain of chronic fatigue or weight loss. Those with ascites due to heart failure may also complain of shortness of breath as well as wheezing and exercise intolerance.

Causes of high serum-ascites albumin gradient (SAAG or transudate) are

[8]

• Cirrhosis – 81% (alcoholic in 65%, viral in 10%, cryptogenic in 6%)
• Heart failure – 3%
• Hepatic venous occlusion: Budd–Chiari syndrome or veno-occlusive disease
• Constrictive pericarditis
• Kwashiorkor (childhood protein-energy malnutrition)

Causes of low SAAG ("exudate") are

• Cancer (metastasis and primary peritoneal carcinomatosis) – 10%
• Infection: Tuberculosis – 2% or spontaneous bacterial peritonitis
• Pancreatitis – 1%
• Serositis
• Nephrotic syndrome[9]
• Hereditary angioedema[10]

Other rare causes

• Meigs syndrome
• Vasculitis
• Hypothyroidism
• Renal dialysis
• Peritoneum mesothelioma
• Abdominal tuberculosis
• Mastocytosis

Ascites in a person with abdominal cancer as seen on ultrasound

Liver cirrhosis with ascites

Routine complete blood count (CBC), basic metabolic profile, liver enzymes, and coagulation should be performed. Most experts recommend diagnostic paracentesis if the ascites is new or if the person with ascites is being admitted to the hospital. The fluid is then reviewed for its gross appearance, protein level, albumin, and cell counts (red and white). Additional tests will be performed if indicated such as microbiological culture, Gram stain, and cytopathology.[8]

The serum-ascites albumin gradient (SAAG) is probably a better discriminant than older measures (transudate versus exudate) for the causes of ascites.[11] A high gradient (> 1.1 g/dL) indicates the ascites is due to portal hypertension. A low gradient (< 1.1 g/dL) indicates ascites of non-portal hypertensive as a cause.[12]

Ultrasound investigation is often done before attempts to remove fluid from the abdomen. This may reveal the size and shape of the abdominal organs, and Doppler studies may show the direction of flow in the portal vein, as well as detecting Budd–Chiari syndrome (thrombosis of the hepatic vein) and portal vein thrombosis. The sonographer also can estimate the amount of ascitic fluid, and difficult-to-drain ascites may be drained under ultrasound guidance. An abdominal CT scan is more accurate than a sonogram to reveal abdominal organ structure and morphology.[12]

Ascitic fluid can accumulate as a transudate or an exudate. Amounts of up to 35 liters are possible.

Roughly, transudates are a result of increased pressure in the hepatic portal vein (>8 mmHg, usually around 20 mmHg[14] (e.g., due to cirrhosis), while exudates are actively secreted fluid due to inflammation or malignancy. As a result, exudates are high in protein and lactate dehydrogenase and have a low pH (<7.30), a low glucose level, and more white blood cells. Transudates have low protein (<30 g/L), low LDH, high pH, normal glucose, and fewer than 1 white cell per 1000 mm³. Clinically, the most useful measure is the difference between ascitic and serum albumin concentrations. A difference of less than 1 g/dl (10 g/L) implies an exudate.[8]

Portal hypertension plays an important role in the production of ascites by raising capillary hydrostatic pressure within the splanchnic bed.

Regardless of the cause, sequestration of fluid within the abdomen leads to additional fluid retention by the kidneys due to stimulatory effect on blood pressure hormones, notably aldosterone. The sympathetic nervous system is also activated, and renin production is increased due to decreased perfusion of the kidney. Extreme disruption of the renal blood flow can lead to hepatorenal syndrome. Other complications of ascites include spontaneous bacterial peritonitis (SBP), due to decreased antibacterial factors in the ascitic fluid such as complement.

Diagram showing ascites being drained

Ascites is generally treated while an underlying cause is sought, in order to relieve symptoms and to prevent complications and progression. In people with mild ascites, therapy is usually as an outpatient. The goal is weight loss of no more than 1.0 kg/day for people with both ascites and peripheral edema and no more than 0.5 kg/day for people with ascites alone.[15] In those with severe ascites causing a tense abdomen, hospitalization is generally necessary for paracentesis.[16][17]

It has been suggested that ascites was seen as a punishment especially for oath-breakers among the Proto-Indo-Europeans.[34] This proposal builds on the Hittite military oath as well as various Vedic hymns (RV 7.89, AVS 4.16.7). A similar curse dates to the Kassite dynasty (12th century BC).