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Interventional Radiology Updated April 2026

Paracentesis

Ultrasound-guided drainage of peritoneal ascites — indications, pre-procedure checklist, anatomy, complications, and ascitic fluid interpretation.

Key points
Paracentesis access site diagram showing ASIS landmarks and needle entry points lateral to the rectus sheath in the LLQ and RLQ
Paracentesis access sites (X): 3 cm medial and superior to the ASIS bilaterally, lateral to the rectus sheath. Midline infraumbilical approach (green) is an alternative via the avascular linea alba.

Indications

TypeClinical Context
Diagnostic New-onset ascites of unclear etiology; suspected spontaneous bacterial peritonitis (SBP); unexplained clinical deterioration in a patient with known ascites
Therapeutic Symptomatic tense ascites causing dyspnea, abdominal pain, or early satiety; ascites refractory to diuretics

Contraindications

TypeContraindication
Absolute Hemodynamic instability; clinically evident fibrinolysis or DIC; no safe ultrasound access window
Relative Overlying skin infection or cellulitis at access site; prior abdominal surgery with suspected tethered bowel; pregnancy (use ultrasound guidance, avoid gravid uterus); massive organomegaly encroaching on access site

Coagulopathy in cirrhosis: Mild-to-moderate coagulopathy and thrombocytopenia are common in cirrhotic patients and are generally not contraindications to paracentesis. The INR does not reliably reflect bleeding risk in liver disease — these patients have a rebalanced hemostatic system. Routine laboratory correction is not required per SIR guidelines.

Relevant Anatomy

Access Site

The preferred access site is the left or right lower quadrant, approximately 3 cm medial and 3 cm superior to the anterior superior iliac spine (ASIS), lateral to the rectus sheath. This approach avoids the inferior epigastric artery, which runs deep within the rectus abdominis muscle.

A midline infraumbilical approach through the avascular linea alba is an alternative when lateral access is not feasible. Final access site is always determined by real-time ultrasound — the anatomic landmark guides initial probe placement only.

Structures at Risk

Pre-Procedure Checklist

Imaging Review

Labs

Anticoagulation Management

Consent Considerations

Discuss the following risks with the patient: bleeding (including vessel injury), infection, bowel perforation, persistent ascites leak at the puncture site, and post-paracentesis circulatory dysfunction (PPCD) — particularly relevant for large-volume drainage without albumin replacement.

Patient Preparation

Equipment Overview

The following categories of equipment are used. Specific device selection, sizes, and configuration are part of the detailed procedural approach.

Procedure Overview

The following is a high-level summary of the procedural steps. Full step-by-step technique, equipment setup, and periprocedural management are available in RadCall Pro.

  1. Ultrasound survey — identify the largest accessible fluid pocket, confirm no bowel or vessels in the needle path, mark the skin entry site, and measure depth to fluid
  2. Sterile preparation — antiseptic prep and draping of the access site
  3. Local anesthesia — anesthetize skin and soft tissue down to the peritoneum under ultrasound guidance
  4. Needle access — advance the access needle into the peritoneal fluid under real-time ultrasound guidance and confirm fluid return
  5. Specimen collection — aspirate fluid for diagnostic labs (see Fluid Analysis below); for cytology, adequate volume is needed
  6. Therapeutic drainage — connect catheter to vacuum drainage system; drain until patient is comfortable or target volume reached
  7. Removal and dressing — remove catheter, apply sterile dressing; document fluid color, clarity, and total volume removed

Complications

ComplicationRateRecognition & Management
Ascites leak at puncture site ~5% Most common complication; typically self-limited; wound closure techniques or ostomy bag as temporizing measure; optimize technique to reduce tract patency
Abdominal wall hematoma / bleeding <1% Vessel injury (inferior epigastric artery); recognizable on CT as hyperdense collection in abdominal wall; conservative management vs. embolization for large or expanding hematomas
Bowel perforation <1% Typically self-sealing with small-caliber needle; monitor for signs of peritonitis (fever, worsening abdominal pain, leukocytosis); CT abdomen if perforation suspected
Post-paracentesis circulatory dysfunction (PPCD) Up to 20% without albumin Hypovolemia, hyponatremia, and renal impairment occurring 12–72 hours after large-volume drainage; prevented by albumin replacement (6–8 g per liter removed in cirrhotic patients)
Infection Rare Cellulitis or peritonitis from contamination; strict sterile technique is preventive

Post-Procedure Care & Imaging

Monitoring

Albumin Replacement

Imaging Findings to Report

Ascitic Fluid Analysis Reference

TestThresholdInterpretation
SAAG (serum albumin − ascites albumin) ≥ 1.1 g/dL Portal hypertension (cirrhosis, heart failure, Budd-Chiari, portal vein thrombosis) — 97% accuracy
SAAG < 1.1 g/dL Non-portal hypertensive etiology: malignancy, TB peritonitis, pancreatitis, nephrotic syndrome
Cell count — PMN ≥ 250/mm³ Spontaneous bacterial peritonitis (SBP) — begin empiric antibiotics immediately (e.g., cefotaxime)
Total protein ≥ 2.5 g/dL Exudate: malignancy, TB, pancreatitis; <2.5 g/dL = transudate (cirrhosis, heart failure)
Glucose Lower than serum Markedly low or undetectable → suspect bowel perforation or infection
Amylase Elevated vs. serum Pancreatic ascites or bowel perforation
Bilirubin Ascites > serum Biliary or bowel perforation
Triglycerides > 200 mg/dL Chylous ascites: lymphatic obstruction, malignancy, post-surgical
Cytology Malignant cells; sensitivity ~60–75%; adequate volume needed for cellularity
Gram stain / culture Inoculate blood culture bottles at bedside — increases SBP culture yield 50–70% vs. standard tubes

Fluid Appearance

When to Escalate

References


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