Ascites
In medicine (gastroenterology), ascites (also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy) is an accumulation of fluid in the peritoneal cavity. Although most commonly due to cirrhosis and severe liver disease, its presence can portend other significant medical problems. Diagnosis of the cause is usually with blood tests, an ultrasound scan of the abdomen, and direct removal of the fluid by needle or paracentesis (which may also be therapeutic). Treatment may be with medication (diuretics), paracentesis, or other treatments directed at the cause.
Mild ascites is hard to notice, but severe ascites leads to abdominal distension. Patients with ascites generally will complain of progressive abdominal heaviness and pressure as well as shortness of breath due to mechanical impingement on the diaphragm.
Ascites is detected on physical examination of the abdomen by visible bulging of the flanks in the reclining patient ("flank bulging"), "shifting dullness" (difference in percussion note in the flanks that shifts when the patient 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 etiology. For instance, in portal hypertension (perhaps due to cirrhosis or fibrosis of the liver) patients 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.
Diagnosis
Routine complete blood count (CBC), basic metabolic profile, liver enzymes, and coagulation should be performed. Most experts recommend a diagnostic paracentesis be performed if the ascites is new or if the patient 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 Gram stain and cytopathology.
The Serum-ascites albumin gradient (SAAG) is probably a better discriminant than older measures (transudate versus exudate) for the causes of ascites.[3] 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 etiology.
Ultrasound Scan ND 232.jpg
Ultrasound investigation is often performed prior to 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 and portal vein thrombosis. Additionally, the sonographer can make an estimation of the amount of ascitic fluid, and difficult-to-drain ascites may be drained under ultrasound guidance. Abdominal CT scan is a more accurate alternate to reveal abdominal organ structure and morphology.
causes
The most common cause of ascites is advanced liver disease or cirrhosis. Approximately 80% of the ascites cases are thought to be due to cirrhosis. Although the exact mechanism of ascites development is not completely understood, most theories suggest portal hypertension (increased pressure in the liver blood flow) as the main contributor. The basic principle is similar to the formation of edema elsewhere in the body due to an imbalance of pressure between inside the circulation (high pressure system) and outside, in this case, the abdominal cavity (low pressure space). The increase in portal blood pressure and decrease in albumin (a protein that is carried in the blood) may be responsible in forming the pressure gradient and resulting in abdominal ascites.
Other factors that may contribute to ascites are salt and water retention. The circulating blood volume may be perceived low by the sensors in the kidneys as the formation of ascites may deplete some volume from the blood. This signals the kidneys to reabsorb more salt and water to compensate for the volume loss.
Some other causes of ascites related to increased pressure gradient are congestive heart failure and advanced kidney failure due to generalized retention of fluid in the body.
In rare cases, increased pressure in the portal system can be caused by internal or external obstruction of the portal vessel, resulting in portal hypertension without cirrhosis. Examples of this can be a mass (or tumor) pressing on the portal vessels from inside the abdominal cavity or blood clot formation in the portal vessel obstructing the normal flow and increasing the pressure in the vessel (for example, the Budd-Chiari syndrome).
There is also ascites formation as a result of cancers, called malignant ascites. These types of ascites are typically manifestations of advanced cancers of the organs in the abdominal cavity, such as, colon cancer, pancreatic cancer, stomach cancer, breast cancer, lymphoma, lung cancer, or ovarian cancer.
Pancreatic ascites can be seen in people with chronic (long standing) pancreatitis or inflammation of pancreas. The most common cause of chronic pancreatitis is prolonged alcohol abuse. Pancreatic ascites can also be caused by acute pancreatitis as well as trauma to the pancreas.
Treatment
Reclining minimizes the amount of salt the kidneys absorb, so treatment generally starts with bed rest
and a low-salt diet. Urine-producing drugs (diuretics) may be prescribed if initial treatment is ineffective.
The weight and urinary output of patients using diuretics must be carefully monitored for signs of :
* hypovolemia (massive loss of blood or fluid)
* azotemia (abnormally high blood levels of nitrogenbearing materials)
* potassium imbalance
* high sodium concentration. If the patient consumes more salt than the kidneys excrete, increased doses of diuretics should be prescribed Moderate-to-severe accumulations of fluid are treated by draining large amounts of fluid (largevolume paracentesis) from the patient’s abdomen. This procedure is safer than diuretic therapy. It
causes fewer complications and requires a shorter hospital stay.
Large-volume paracentesis is also the preferred treatment for massive ascites. Diuretics are sometimes
used to prevent new fluid accumulations, and the procedure may be repeated periodically.
What are the complications for ascites?
Some complications of ascites can be related to its size. The accumulation of fluid may cause breathing difficulties by compressing the diaphragm and formation of pleural effusion.
Infections are another serious complication of ascites. In patients with ascites related to portal hypertension, bacteria from the gut may spontaneously invade the peritoneal fluid (ascites) and cause an infection. This is called spontaneous bacterial peritonitis or SBP. Antibodies are rare in ascites and, therefore, the immune response in the ascitic fluid is very limited. The diagnosis of SBP is made by performing a paracentesis and analyzing the fluid for the number of white blood cells or evidence of bacterial growth.
Hepatorenal syndrome is a rare, but serious and potentially deadly (average survival rates range from 2 weeks to about 3 months) complication of ascites related to cirrhosis of the liver leading to progressive kidney failure. The exact mechanism of this syndrome is not well known, but it may result from shifts in fluids, impaired blood flow to the kidneys, overuse of diuretics, and administration of contrasts or drugs that may be harmful to the kidney.
prevention
The prevention of ascites largely involves preventing the risk factors of the underlying conditions leading to ascites.
In patients with known advanced liver disease and cirrhosis of any cause, avoidance of alcohol intake can markedly reduce the risk of forming ascites. Nonsteroidal antiinflammatory drugs [ibuprofen (Advil, Motrin, etc.)] should also be limited in patients with cirrhosis as they may diminish the blood flow to the kidneys, thus, limiting the salt and water excretion. Complying with dietary salt restrictions is also another simple preventive measure to reduce ascites.
