Ascites (/əˈsaɪtiz/;[5] Greek: ἀσκός, romanized: askos, meaning "bag" or "sac"[6]) is the abnormal build-up of fluid in the abdomen.

[4] Other causes include cancer, heart failure, tuberculosis, pancreatitis, and blockage of the hepatic vein.

[4] The Latin ascites, originally from Greek (askites [ασκίτης]), meant "bag-like dropsy," from askós (ἀσκός), a leather bag or sheepskin (“wineskin”) used for carrying wine, water or oil.

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.

[8] 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).

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.

The fluid is then reviewed for its gross appearance, protein level, albumin, and cell counts (red and white).

[9] The serum-ascites albumin gradient (SAAG) is probably a better discriminant than older measures (transudate versus exudate) for the causes of ascites.

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

The sympathetic nervous system is also activated, and renin production is increased due to decreased perfusion of the kidney.

Ascites is generally treated while an underlying cause is sought, in order to relieve symptoms and to prevent complications and progression.

Spironolactone (or other distal-tubule diuretics, such as triamterene and amiloride) is the drug of choice, because it blocks the aldosterone receptor in the collecting tubule.

[25] A random urine sodium-to-potassium ratio of > 1 is 90% sensitivity in predicting negative balance (> 78-mmol/day sodium excretion).

[27] If the person exhibits a resistance or poor response to diuretic therapy, ultrafiltration or aquapheresis may be needed to achieve adequate control of fluid retention and congestion.

[28][29] In those with severe (tense) ascites, therapeutic paracentesis may be needed in addition to medical treatments listed above.

A 2006 meta-analysis concluded that "TIPS was more effective at removing ascites [than] paracentesis[,] without a significant difference in mortality, gastrointestinal bleeding, infection, and acute renal failure.