Diagnostics & Procedures · Topic 13 of 16

Paracentesis

Procedures · ascites

Paracentesis

Tap new ascites and every cirrhotic admission to find SBP; skip routine plasma or platelets, and give albumin 6–8 g per liter above 5 L.

Key numbers

Albumin 6–8 g/L above 5 L> 5 L → 6–8 g/L

Ascitic PMN over 250/mm³ means SBPPMN > 250/mm³

SAAG of 1.1 or more means portal hypertensionSAAG ≥ 1.1 g/dL

01 · DoAlbumin 6–8 g/L above 5 L

When more than 5 L is removed, give IV albumin 6–8 g per liter removed to prevent post-paracentesis circulatory dysfunction (hypotension, AKI or hepatorenal syndrome, hyponatremia).

02 · Defined byAscitic PMN over 250/mm³ means SBP

An ascitic neutrophil (PMN) count above 250/mm³ diagnoses spontaneous bacterial peritonitis: start empirical IV antibiotics and albumin without waiting for the culture (see Ascites & SBP).

03 · The ruleNo routine plasma or platelets beforehand

Coagulopathy and thrombocytopenia (even INR > 1.5 or platelets < 50,000) do not contraindicate paracentesis, and routine plasma or platelet transfusion beforehand is not recommended; DIC is the possible exception.

Diagnosis & monitoring

Work-up

Tap new ascites and every cirrhotic admission must knowDo a diagnostic paracentesis for new-onset ascites, for every patient with cirrhotic ascites admitted emergently (even without signs of infection), and whenever fever, abdominal pain, encephalopathy, AKI or unexplained deterioration appears.

SAAG of 1.1 or more means portal hypertensionSerum-ascites albumin gradient (serum minus ascitic albumin, drawn the same day) ≥ 1.1 g/dL points to portal hypertension (cirrhosis, heart failure, Budd-Chiari); < 1.1 g/dL points to carcinomatosis, tuberculosis, pancreatitis or nephrotic syndrome.

Management

Orders

Order cell count, albumin, protein and cultureSend ascitic fluid for gross appearance, cell count with differential, albumin, total protein and culture; add cytology, acid-fast stain or amylase when the clinical picture suggests cancer, tuberculosis or pancreatitis.

Inoculate blood culture bottles at the bedsideTransfer ascitic fluid into blood culture bottles at the bedside, which increases culture sensitivity, and draw peripheral blood cultures as well when infection is suspected.

Left lower quadrant, lateral to the rectus sheathEnter the left lower quadrant 3–5 cm superior and medial to the anterior superior iliac spine, lateral to the rectus sheath (inferior epigastric artery), over dullness, or the midline 2 cm below the umbilicus.

Use a Z-track to prevent leakageUse a Z-track (skin traction or angled) insertion so the tract seals when the needle is removed, advance slowly with intermittent rather than continuous suction, and apply a pressure dressing if fluid keeps leaking.

Tense ascites: large-volume paracentesis first-lineLarge-volume paracentesis is first-line for tense (grade 3) and refractory ascites; removing 5–6 L is generally well tolerated, and refractory ascites should prompt referral for TIPS or transplant evaluation.

Red flags & don'ts

Avoid harm

Watch for bleeding, leak and bowel perforation complicationComplications are uncommon: abdominal wall or intraperitoneal hemorrhage (can be fatal), persistent fluid leak, infection, bowel perforation and, after large volumes, hypotension, transient hyponatremia and rising creatinine.

Avoid scars; use ultrasound when anatomy is distorted avoidAvoid an infected abdominal wall and bowel obstruction with distention unless imaging finds a safe pocket; move away from surgical scars (adherent bowel) and use ultrasound with a large mass or in pregnancy.

Commonly confused

Tell apart

Mixed flora suggests perforation, not SBPSBP usually involves a single organism; mixed flora on ascitic culture suggests a perforated viscus (secondary peritonitis), which needs imaging and surgical evaluation rather than antibiotics alone.

More detail

Reference

Show 6 reference facts

Post-paracentesis circulatory dysfunction (AKI or HRS, dilutional hyponatremia, encephalopathy) becomes more likely when more than 8 L is removed in one session, even with albumin.

Monitor blood pressure for 2–4 hours after a large-volume paracentesis.

A repeat paracentesis 48 hours into SBP treatment can assess response: a PMN fall of less than 25% from baseline means treatment failure — broaden antibiotics and look for secondary peritonitis.

Bacterascites — a positive culture with PMN < 250/mm³ and no signs of infection — is not treated; repeat the paracentesis to check for progression to SBP.

Ultrasound guidance is recommended in the ICU and whenever percussion cannot confirm fluid without overlying bowel; prominent abdominal-wall collaterals from portal hypertension are a relative contraindication at that site.

For a diagnostic tap, 30–50 mL of fluid is enough for cell count, chemistry and culture bottles; therapeutic drainage uses a larger catheter (eg, a 15-gauge Caldwell needle) into vacuum bottles.

Pearl

A high INR is not a reason to skip the tap — albumin, not plasma, is what a large-volume paracentesis needs.

Sources · Biggins SW et al. Diagnosis, Evaluation, and Management of Ascites, Spontaneous Bacterial Peritonitis and Hepatorenal Syndrome: 2021 Practice Guidance by the AASLD. Hepatology 2021;74:1014–1048 · Merck Manual Professional — How To Do Paracentesis (reviewed Apr 2025) · Merck Manual Professional — Ascites · Merck Manual Professional — Spontaneous Bacterial Peritonitis (SBP) · Khan S, Linganna M. Diagnosis and management of ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome. Cleve Clin J Med 2023;90:209–213 (summarizes AASLD 2021) · Things We Do for No Reason: Routine correction of elevated INR and thrombocytopenia prior to paracentesis in patients with cirrhosis. J Hosp Med (The Hospitalist reprint) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).