Paracentesis

Paracentesis is a procedure in which a needle or catheter is inserted into the peritoneal cavity to obtain ascitic fluid for diagnostic or therapeutic purposes.

Ascitic fluid may be used to help determine the etiology of ascites, as well as to evaluate for infection or presence of cancer. With regard to differentiation of transudate from exudate, the preferred means for characterizing ascites is the serum-ascitic albumin gradient (SAAG).

Diagnostic tap is used for the following:

New-onset ascites - Fluid evaluation helps to determine ethology, differentiate transudate versus exudate, detect the presence of cancerous cells, or address other considerations
Suspected spontaneous or secondary bacterial peritonitis Refractory ascites

Therapeutic tap is used for the following:

Respiratory compromise secondary to ascites. Abdominal pain or pressure secondary to ascites (including abdominal compartment syndrome)
Non-hypertriglyceridemia-induced severe acute pancreatitis with triglyceride elevation and pancreatitis-associated ascitic fluid.

Large-volume paracentesis is often required in patients with refractory ascites.

Definitive management for abdominal compartment syndrome (ACS) usually consists of performing emergency surgical decompression by means of a laparotomy.

It is well known that liver cirrhosis, when advanced, can cause moderate-to-severe ascites leading to impairment in the respiratory pattern.

Contraindications

An acute abdomen that requires surgery is an absolute contraindication.
Severe thrombocytopenia (platelet count < 20 × 103/μL) and coagulopathy (international normalized ratio INR >2.0) are relative contraindications.

Patients with an INR greater than 2.0 should receive fresh frozen plasma (FFP) prior to the procedure. One strategy is to infuse one unit of fresh frozen plasma before the procedure and then perform the procedure while the second unit is infusing.

Patients with a platelet count lower than 20 × 103/μL should receive an infusion of platelets before the procedure.

In patients without clinical evidence of active bleeding, routine laboratory tests such as prothrombin time (PT), activated partial thromboplastin time (aPTT), and platelet counts may not be needed before the procedure. In these patients, pretreatment with FFP, platelets, or both before paracentesis is also probably not needed.