Diagnostic abdominal paracenteses are frequently performed in the ED for patients with known liver disease. What complications can occur? What if the INR is elevated, as in many patients with liver disease?
1) Complications of abdominal paracentesis include: ascitic fluid leakage (5%), bleeding (0-0.97%), bowel infection (0.58-0.63%), bowel perforation and mortality (0-0.39%). 
To further minimize these risks, ultrasound-guidance is recommended to identify a suitable pocket of ascites and a “Z-track” insertion technique can be used. The needle insertion site should be superior to the ASIS and lateral to the inferior epigastric artery (which extends from the external iliac artery).
A 2005 study conducted in a Canadian liver unit found 9 cases of severe hemorrhagic complication with 7 deaths after 4729 paracenteses. It was notable for a mean PLT count of 102 ± 37 and a mean INR of 2.0 ± 0.9. The patients with complications had higher MELD/Child-Pugh scores and complication rate was not related to operator experience or INR/PLT level. 
One systematic review published in 2014 looking at hemorrhagic complications after paracentesis shows that the most common complications were abdominal wall hematomas (52%), hemoperitoneum (41%) and pseudoaneurysm (7%). 
2) Patients who require a paracentesis frequently have significant liver disease with elevated INR and low PLT counts. Multiple societies (AASLD, IAC and EASL) state that paracentesis can still be performed and do not require a pre-procedural correction of these parameters.
1) Runyon BA. Diagnostic and therapeutic abdominal paracentesis. Feb 2014. Uptodate
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4) Sharzehi K, Jain V, Naveed A, Schreibman I. Hemorrhagic complications of paracentesis: a systemic review of literature. Gastroenterol Res Pract. 2014;2014:985141. Epub 2014 Dec.