Print Friendly, PDF & Email

Ascitic tap (paracentesis)

Ideally all ascitic interventions should be ultrasound guided

Indications for ascitic tap (paracentesis)

  • To aid diagnosis of the cause of ascites or in the diagnosis or exclusion of SBP
    • A diagnostic paracentesis should be performed in all patients with new onset grade 2 or 3 ascites, and in all patients hospitalized for worsening of ascites or any complication of cirrhosis
Grade of ascites Definition Treatment
1 Mild ascites only detectable by ultrasound No treatment
2 Moderate ascites evident by moderate symmetrical distension of abdomen Restriction of sodium and diuretics
3 Large ascites with marked abdominal distension Large volume paracentesis followed by treatment as for (2)

Equipment required for ascitic tap (paracentesis)

  • Ultrasound (ideally)
  • Dressing trolley & sharps bin
  • Sterile field
    • Sterile dressing pack
    • Sterile gloves
    • 2% Chlorhexadine swabs
  • Analgesia
    • 10mls of 1% or 2% Lidocaine
    • Orange (25G) needle (x1)
    • Green (19G) needle (x1)
    • 10ml Syringe (x1)
  • 20ml Syringe (x1)
    • with green (19G) needle (x1)
  • Specimen containers
  • Blood culture bottles
  • Dressing

Contraindications to ascitic tap (paracentesis)

  • Overlying infection
    • Chose another site
  • Cautions – but not contraindications
    • Coagulopathy (INR>2.0)
      • Attempt to correct INR to <1.5 if possible.
    • Platelets<50
      • Thrombocytopenia and coagulopathy is often present in liver disease and though it is a caution, it not a contraindication to paracentesis or drainage
      • The incidence of clinically significant bleeding is low; routine FFP or platelets is not indicated
    • Pregnancy
    • Organomegaly
    • Obstruction/ileus
    • Distended bladder
    • Abdominal adhesions


  • Consent patient and explain procedure
    • Consent for infection, bleeding, pain, failure, damage to surrounding structures (especially bowel perforation – rare), leakage
  • Lie patient flat and examine clinically to confirm ascites
  • Ultrasound area for insertion
    • Define landmarks
    • Aim for 1/3 to ½ of the way between the anterior superior iliac spine and the umbilicus avoiding vessels and scars

Procedure for ascitic tap (paracentesis)

  • Position the patient supine in the bed with their head resting on a pillow.
  • Select an appropriate point on the abdominal wall in the right or left lower quadrant, lateral to the rectus sheath. If a suitable site cannot be found with palpation and percussion consider using ultrasound to mark a spot.
  • Clean the site and surrounding area with 2% Chlorhexadine and apply a sterile drape.
  • Anaesthetise the skin with Lidocaine using the orange needle.
  • Anaesthetise deeper tissues using the green needle, aspirating as you insert the needle to ensure you are not in a vessel before infiltrating with lidocaine. Use a maximum of 10mls of Lidocaine.
  • Take a clean green needle and 20ml syringe and insert through the skin advancing and aspirating until fluid is withdrawn
  • Aspirate 20ml
  • Remove needle and apply sterile dressing


NEJM video on paracentesis

Samples in paracentesis

  • Microbiology
    • Microscopy, culture & sensitivities (be explicit if yeast or mycobacterium suspected)
    • Culture in blood culture bottles inoculated at the bedside
  • Haematology
    • Automated WCC count (send EDTA sample)
  • Biochemistry
    • Albumin, Protein, LDH, Glucose
    • Remember to send a serum albumin, LDH and glucose at the same time (or at least from the same day).
    • Special tests: Fluid amylase,  Triglycerides, Bilirubin
  • Cytology
    • Sent the largest sample
  • Samples can also be sent for immunology (RF, ANA) and TB culture if clinically indicated

In the event of failure

  • Stop procedure
  • Seek senior help
  • Consider further imaging or aspiration in radiology

Top Tips for ascitic tap (paracentesis)

  • Always send the most fluid to cytology, especially if malignancy is suspected. The more fluid sent, the higher the diagnostic yield.
  • Never dispose of unused fluid, put it in an extra pot and add to the cytology sample.
  • If you want to gain a larger sample use a 50ml syringe to aspirate fluid
  • In patients with a thick abdominal wall a spinal needle can be used to infiltrate anaesthetic and check position.
  • If you aspirate blood when infiltrating an anaesthetic; stop, withdraw your needle, change position by 1-2cm and try again.

Click here for medical student OSCE and PACES examples of ascitic fluid analysis

Common ascitic flid interpretation exam questions for medical students, finals, OSCEs and MRCP PACES


Click here to download free teaching notes on doing an ascitic tap (paracentesis): Procedures – Ascitic tap

Perfect revision for medical students, finals, OSCEs and MRCP PACES