Paracentesis

Paracentesis, or abdominal paracentesis, is a medical procedure used to remove ascitic fluid from the peritoneal cavity with a needle or catheter. It is typically performed under sterile conditions and often with ultrasound guidance to improve safety and accuracy. The procedure serves diagnostic purposes, such as analyzing the fluid for infection, cytology, or malignancy, and therapeutic purposes, to relieve symptoms from ascites including abdominal distension and shortness of breath.

Indications include evaluation of new-onset ascites, suspected infection of ascitic fluid (spontaneous bacterial peritonitis), assessment of malignant involvement, and monitoring response to therapy. Therapeutic paracentesis is commonly performed in patients with tense ascites secondary to cirrhosis or malignancy to reduce intra-abdominal pressure and improve breathing and comfort.

Procedure and sample handling: The patient is positioned for access to a suitable fluid pocket, usually in the lower abdomen or flank. After sterile preparation and local anesthesia, a needle or small-bore catheter is inserted into the ascitic space to withdraw fluid. Fluid is collected for laboratory analysis, including cell count with differential, total protein, albumin, cultures, and cytology. The serum-ascites albumin gradient (SAAG) is often calculated to help determine the cause of ascites (SAAG ≥1.1 g/dL suggests portal hypertension). In large-volume paracentesis (commonly >5 liters), intravenous albumin is usually administered (about 6–8 g for every liter removed) to reduce the risk of circulatory dysfunction.

Complications and safety: Potential adverse events include bleeding, infection, bowel or vessel injury, leakage at the puncture site, hypotension, and renal impairment. Use of ultrasound guidance and sterile technique reduces risk, and patients are monitored after the procedure for signs of complications. In suspected spontaneous bacterial peritonitis (SBP), an ascitic fluid neutrophil count ≥250 cells/µL warrants antibiotic treatment.