Subinternship Medicine · Year 4 · from Subinternship Medicine
Case 2: Paracentesis for Spontaneous Bacterial Peritonitis
Clinical Image
Source: Wikimedia Commons - Ultrasound - CC BY-SA 3.0
Case Presentation
A 62-year-old man with alcoholic cirrhosis (Child-Pugh C) presents with increasing abdominal distension, diffuse abdominal tenderness, and confusion. He is afebrile but appears ill. His abdomen is tense with shifting dullness. Per protocol, diagnostic paracentesis is performed on all cirrhotic patients admitted to the hospital. The sub-intern performs the procedure using ultrasound guidance. The patient is positioned supine with slight leftward tilt. Ultrasound identifies a large pocket of ascites in the left lower quadrant, lateral to the rectus muscle to avoid the inferior epigastric vessels. Using sterile technique, the sub-intern infiltrates local anesthesia to the peritoneum and uses Z-track technique (offsetting skin and deep entry points) to reduce post-procedure leak. A needle is inserted perpendicular to the skin, aspirating as it advances. Straw-colored fluid is obtained. She collects 60 mL: inoculating blood culture bottles at bedside (10 mL each, aerobic and anaerobic), sending cell count with differential, albumin, and total protein. Results return showing ascitic fluid WBC 850/microL with 420 polymorphonuclear cells (PMN greater than 250), ascitic albumin 0.8 g/dL (serum albumin 2.4 g/dL, SAAG = 1.6). The diagnosis is spontaneous bacterial peritonitis (SBP). Ceftriaxone 2g IV daily is initiated, along with albumin 1.5 g/kg on day 1 and 1 g/kg on day 3 (for hepatorenal syndrome prophylaxis). Cultures later grow E. coli.
Key Learning Points
- All patients with cirrhosis admitted to the hospital should have diagnostic paracentesis to evaluate for SBP, regardless of symptoms
- SBP is diagnosed when ascitic fluid PMN count is greater than 250/microL; cultures are positive in only about 50% of cases
- SAAG (serum-ascites albumin gradient) greater than 1.1 g/dL indicates portal hypertension; less than 1.1 suggests non-portal hypertension causes (malignancy, infection, pancreatitis)
- Z-track technique and lateral insertion (avoiding the rectus sheath) minimize complications of bleeding and persistent leak