Fluid In The Abdomen

Fluid in the abdominal cavity is technically known as so-called ascites. It almost always indicates the presence of a serious disease. Even if it emerges by an otherwise asymptomatic and healthy-looking person, it must be cautiously examined.


Portal hypertension

Portal vein is a very important vessel. It arises by fusion of veins leading venous blood from intestines and spleen towards the liver. In liver tissue, portal vein breaks up into small veins. Nutrients and toxic products from the gut come into close contact with liver to detoxify pollutants and to process the nutrients. Subsequently, blood leaves liver via hepatic veins. These veins later connect and flow into the inferior vena cava.


There are many disease conditions in which blood accumulates in portal vein with portal pressure increase (so-called portal hypertension). It is usually due to disruption of blood flow by a local obstruction or because of poor heart pumping function. Accumulating blood can begin to “filtrate” from portal vein outside into abdominal cavity and ascites occurs. The most common reasons of portal hypertension are:


a) Liver cirrhosis – Cirrhotic liver tissue resists the blood flow causing blood accumulation in portal vein.


b) Heart failure – The failure of right half of the heart causes blood stasis in begins to accumulate in front of her blood. This can lead to venous stasis in inferior vena cava, in liver tissue (liver congestion) and finally in portal vein itself.


c) Oppression by tumors – Tumors located near portal vein may cause its oppression, narrowing and obstruction. This may include liver cancer, pancreatic cancer, gallbladder cancer and other biliary tract tumors.


d) Portal vein thrombosis – Blood clot inside the portal vein forms a barrier to the blood flow and may lead to local blood pressure increase.


e) Budd-Chiari syndrome - This is a very rare cause of portal hypertension. It means a closure of hepatic veins that drain blood into the inferior vena cava.


Malignant diseases of the abdominal cavity

Tumors in close contact with the abdominal cavity may cause a fluid secretion. Typically in women it is the cause of ovarian cancer. Other abdominal organ cancers may have the same effect (gastric cancer, liver cancer, gallbladder cancer, etc.).

Inflammation of the abdominal cavity

Inflammation processes in the abdominal cavity may also be associated with formation of ascites. To create a clinically evident ascites, there must be an extensive inflammation present such as diffuse peritonitis.

Lack of blood proteins (hypoproteinemia)

Proteins keep fluid in blood vessels. Protein deficiency leads to leakage of blood fluid (but not blood cells) from vessels to tissues causing their swelling. Many cases of ascites formation due to hypoproteinemia are found in malnutrition (bloated bellies of African children are actually full of fluid), or protein losses (such as loss of proteins in the urine in nephrotic syndrome).


Bigger form of ascites present as enlarged abdomen, sometimes it may be bloated, tight as a drum and very poorly palpable. Palpation and percussion is usually painless. Ascites has many possible complications. When lying down abdominal cavity full of water can compress the diaphragm and lungs and cause an acute respiratory distress. Ascitic fluid may be infected by bacteria that migrate into it from guts. Intestines inside abdominal cavity abdominal cavity can be compressed by the fluid resulting in constipation. In rare cases, the fluid in abdomen can be so pressurized that a weaker spot in abdominal wall may rupture and ascites fluid starts to flow out.

Diagnostic approach

It is based on physical examination – view and palpation of the abdomen. It is however often difficult to absolutely confirm ascites presence by physical examination. Small ascites may be quite discrete, extensive ascites can be confused with obesity. Therefore, it is advisable to use imaging techniques such as abdominal ultrasound. It will show fluid in abdomen, helps to estimate its amount and determine an ideal place to pierce the abdominal wall (paracentesis, ascitic tap). If we decide to obtain a sample of fluid from the abdomen, the abdominal wall is pierced with a needle and certain amount of fluid is let out. The samples are investigated biochemically (amount of protein, sugar, fat, etc.) and in a microbiological laboratory (presence or absence of bacteria). Fluid cytology is very important in discovery of white blood cells (by inflammation), or discovery of tumor cells.


If possible, the underlying cause must be solved (treatment of cancer, substitution of missing proteins, inflammation treatment, liver transplant etc.). If we are not able to do so (such as in severe cirrhosis), we can at least try some medication. Diuretic agents have often good effect, especially in liver cirrhosis ascites. Reduction of portal hypertension can be achieved by nitrates and certain antihypertensive agents. In some cases TIPS is performed to quickly and efficiently lower portal hypertension by allow the blood to flow directly through liver. If there is bacteria presence in ascites, we treat the patient with antibiotics.


Extensive ascites causing clinical troubles can be drained. Abdominal wall is pierced by a needle and the fluid is let out. It is connected with a great relief. Before the puncture it is appropriate to do an abdominal ultrasound to find a safe spot, where there is only a small risk to perforate an intestinal loop. If we drop too much ascitic fluid, the patient must be administered proteins intravenously fluid. If we do not resolve the cause of ascites formation, fluid in the abdomen tends to reappear.

Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources