Ascites
Updates to Article Attributes
Ascites is defined as an abnormal amount of intraperitoneal fluid.
Clinical presentation
Patients with a large volume of ascites can present with abdominal distension (which may be painful), nausea, vomiting, dyspnoea and peripheral oedema 7, 9.
Pathology
Ascitic fluid is traditionally characterised as either:
- transudate: thin, low protein count and low specific gravity
- exudate: high protein count and specific gravity
More recently, the concept of the serum-ascites albumin gradient has been shown to be more accurate in the classification of the causes of ascites 5. For the purposes of simplicity, however, we maintain the former classification.
Aetiology
Causes of transudative ascites:
- hepatic cirrhosis
- alcoholic hepatitis
- heart failure (CCF)
- hypoproteinaemia
- portal vein thrombosis
- peritoneal dialysis
- malignancy (~10% of refractory ascites) 7, 9
- most commonly: breast, ovarian, endometrial, gastrointestinal and pancreatic 7
Causes of exudative ascites:
- peritoneal carcinomatosis
- pancreatitis
- abscess
- nephrotic syndrome
- peritonitis, e.g. tuberculosis
- ischaemic bowel
- bowel obstruction
Radiographic features
Plain radiograph
Detection of intraperitoneal fluid on a plain radiograph requires at least 500 mL to be present.
Plain filmradiograph findings of ascites include:
- diffusely increased density of the abdomen
- poor definition of the soft tissue shadows, such as the psoas muscles, liver and spleen
- medial displacement of bowel and solid viscera (away from the properitoneal fat stripe)
- bulging of the flanks
- increased separation of small bowel loops
-
Dog ear sign
- represents: represents fluid in pelvic peritoneal recess10
Ultrasound
May detect smaller volumes especially if it's adjacent to the diaphragm or anterior margin of the liver 3. Assessment of fluid type:
- simple ascites is anechoic
- exudative, haemorrhagic or neoplastic ascites contains floating debris
- septations suggest an inflammatory or neoplastic cause and may be called a loculated ascites
CT
CT is most sensitive to small amounts of fluid in the peritoneum which collects preferentially in the dependent regions, such as Morison pouch and the pelvis. The CT density of intraperitoneal fluid may give a clue to the underlying aetiology:
- transudative ascites density should be approximate to that of water (-10 to +10 HU)
- exudative ascites (density >15 HU)
- haemoperitoneum density is higher still (~45 HU)
Of course, other intra- or extra-abdominal CT features may give further evidence to the origin of the ascites (e.g. features of heart failure, features of cirrhosis, peritoneal catheter in situ, etc).
Treatment and prognosis
Medical management includes a modified diet (restricting sodium) and the use of medications such as diuretics 7, 9. Interventional techniques for management include serial paracentesis (ascitic tap), TIPS or peritoneovenous shunting 8, 9 .
Ascitic taps are the most common and thought to be the most effective treatment for symptomatic ascites 9. It can be performed with a variety of techniques depending on the institution and the availability of imaging resources 8:
- blind: i.e. non-imaging guided
- partially imaged-guided: an appropriate site is marked on the abdominal wall using ultrasound but the puncture is blind
- imaging-guided: usually using ultrasound
Differential diagnosis
Consider other causes of intraperitoneal fluid:
- physiological: small amount of pelvic fluid may be normal in young females
- haemoperitoneum
- chylous ascites
- biloma/bile leak
- urinoma/urine leak, e.g. from bladder trauma
-</ul><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Detection of intraperitoneal fluid on a plain radiograph requires at least 500 mL to be present.</p><p>Plain film findings of ascites include:</p><ul>- +</ul><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Detection of intraperitoneal fluid on a plain radiograph requires at least 500 mL to be present.</p><p>Plain radiograph findings of ascites include:</p><ul>
-<a href="/articles/dog-ear-sign-abdomen">Dog ear sign</a>- represents fluid in pelvic peritoneal recess</li>- +<a href="/articles/dog-ear-sign-abdomen">Dog ear sign</a>: represents fluid in pelvic peritoneal recess <sup>10</sup>
- +</li>
-</ul><p>Of course, other intra- or extra-abdominal CT features may give further evidence to the origin of the ascites (e.g. features of heart failure, features of cirrhosis, peritoneal catheter in situ, etc).</p><h4>Treatment and prognosis</h4><p>Medical management includes a modified diet (restricting sodium) and use of medications such as diuretics <sup>7, 9</sup>. Interventional techniques for management include serial paracentesis (ascitic tap) , <a href="/articles/tips">TIPS</a> or <a href="/articles/peritoneovenous-shunting">peritoneovenous shunting</a> <sup>8, 9</sup> .</p><p><a href="/articles/abdominal-paracentesis">Ascitic taps</a> are the most common and thought to be the most effective treatment for symptomatic ascites <sup>9</sup>. It can be performed with a variety of techniques depending on the institution and the availability of imaging resources <sup>8</sup>:</p><ul>- +</ul><p>Of course, other intra- or extra-abdominal CT features may give further evidence to the origin of the ascites (e.g. features of heart failure, features of cirrhosis, peritoneal catheter in situ, etc).</p><h4>Treatment and prognosis</h4><p>Medical management includes a modified diet (restricting sodium) and the use of medications such as diuretics <sup>7, 9</sup>. Interventional techniques for management include serial <a title="Abdominal paracentesis" href="/articles/abdominal-paracentesis">paracentesis</a> (ascitic tap), <a href="/articles/tips">TIPS</a> or <a href="/articles/peritoneovenous-shunting">peritoneovenous shunting</a> <sup>8, 9</sup> .</p><p><a href="/articles/abdominal-paracentesis">Ascitic taps</a> are the most common and thought to be the most effective treatment for symptomatic ascites <sup>9</sup>. It can be performed with a variety of techniques depending on the institution and the availability of imaging resources <sup>8</sup>:</p><ul>
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