A specimen-collecting 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. [ http://orcid.org/0000-0002-2443-7325 http://en.wikipedia.org/wiki/Paracentesis http://www.ncbi.nlm.nih.gov/pubmed/32405060 ]