• Diagnostic
    • Determine the cause of new onset ascites, ascites of unknown origin, or suspected malignant ascites
    • Suspicion of bacterial peritonitis in a patient with known ascites with associated pyrexia, hypotension, tachycardia or encephalopathy.
  • Therapeutic
    • Remove excess intraperitoneal fluid to assist respiration and provide symptomatic relief.


  • Problems at proposed puncture site
    • Local skin infection/cellulitis
    • Hernia
    • Caput medusae or superficial veins
  • Uncooperative patient
  • Uncorrected bleeding diathesis
  • Suspected abdominal adhesions or loculated collections of fluid
  • Significant bowel distension.


  • Sterile dressing pack
  • Gauze swabs
  • Sticking plaster
  • Local anaesthetic (10 mL 2% lignocaine)
  • Syringes: 10 mL, 20 mL, 50-mL Luer-lock
  • Needles: 21G ´2, 27G ´ 1
  • Cannula 16G or peritoneal dialysis catheter, suprapubic catheter or ascitic drain
  • Skin preparation fluid (chlorhexidine)
  • Sterile gloves
  • 3-way tap
  • Scalpel with blade
  • Ensure patient has a patent IV line with normal saline attached

Procedural Technique

  • Record baseline observations of HR, BP, RR and oxygen saturation. Record pre-drainage weight if therapeutic procedure.
  • Explain the procedure to the patient.
  • Ask the patient to empty bladder immediately before commencing the procedure to reduce the risk of inadvertent puncture.
  • Lay the patient on a bed and expose the whole abdomen fully. Percuss the abdomen to demonstrate shifting dullness and the extent of the ascites.
  • Identify the landmarks for proposed puncture site, confirm dullness to percussion and mark with a pen.
  • The safest and preferred site is 2 fingerbreadths below the umbilicus in the midline. Have the patient semi-recumbent at 45–60 degrees.
    • Alternative sites include the right and left lower quadrants, 2–3 fingerbreadths above the inguinal ligament. These sites are only suitable for patients with significant ascites and best accessed with the patient lying slightly towards the side of needle insertion, to reduce the risk of large bowel perforation.
      Note: If the ascites is poorly defined clinically do not proceed, but request an ultrasound scan to mark the best puncture site.
  • Using sterile technique put on your gloves, clean and drape the proposed entry site
  • Draw up 10 mL lignocaine 2%.
    • Use the 27G needle to raise a subcutaneous bleb on the surface of the skin at the proposed entry site.
    • Infiltrate local anaesthetic with the 21G needle beneath the skin and working towards the peritoneum.
    • Take care to draw back on the syringe before infiltrating and stop when fluid is aspirated. Aspirating fluid also confirms correct placement.

Diagnostic Tap

  • Attach a new 21G needle to a 20-mL syringe and insert along the anaesthetised track, bevel up, at 90 degrees to the surface of the skin.
  • Maintain constant negative pressure on the syringe by drawing back on the plunger as the needle is advanced.
  • When fluid is aspirated, withdraw 20 mL of fluid.
  • Remove the needle and press firmly over the site with gauze.
  • Send fluid for biochemistry (protein, glucose, LDH), microbiology (MCS and Gram stain) and cytology.
  • Apply an occlusive dressing.

Therapeutic Tap

  • Cannula
  • Insert a 16G cannula along the anaesthetised track at 90 degrees to the surface of the skin. When a flashback is seen, hold the stylet steady and advance the plastic sheath fully into the peritoneal cavity.
  • Remove the stylet and place a gloved thumb over the cannula. Attach the 3-way tap and 50-mL syringe and secure the cannula with tape.
  • Withdraw fluid into the syringe and switch the 3-way tap settings to empty the syringe contents into an appropriately sized container.
  • Suprapubic catheter, peritoneal dialysis catheter or ascitic drain
  • These are all manufactured with their own blunt introducer, which is less likely to cause bowel perforation.
  • Nick the skin over the anaesthetised track with a scalpel blade. Enter the skin at 90 degrees and gently push the device through the peritoneum into the abdominal cavity.
  • Aspirate the catheter with a 20-mL syringe to ensure ascitic fluid is aspirated, withdraw the introducer, and advance the plastic sheath as far into the peritoneum as it will go.
  • Attach to drain and secure catheter to the skin with tape or a single Clamp the drain after 1000 mL of fluid has been removed.
  • Note: Large volume therapeutic aspiration (>1500 mL) must be accompanied by IV volume and albumin replacement (500 mL normal saline and 1 unit 20% albumin for every 2000 mL drained).
  • Never drain more than 5000 mL during a single therapeutic procedure (risk of profound hypotension).


  • Shock
  • Hypovolaemia
  • Renal failure
  • Perforation of viscera (bowel, bladder)
  • Peritonitis
  • Haemorrhage (e.g. from an abdominal wall vessel laceration).

Handy Hints

  • No aspiration
    • Re-percuss the abdomen and try again. If still unsuccessful, request an ultrasound.
  • No drainage
    • Kinked or blocked tube: untwist and flush with sterile saline.
    • Drain not secured properly and no longer in peritoneum: remove drain and re-site.

Date implemented – 05/2009
Review date – currently being revised
Author – Mike Cadogan

Dr James Wheeler
Dr James Wheeler

Emergency Physician, SCGH, WA, Australia

Articles: 499

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